JPH09311125A - Acoustic impedance measuring device - Google Patents
Acoustic impedance measuring deviceInfo
- Publication number
- JPH09311125A JPH09311125A JP8128377A JP12837796A JPH09311125A JP H09311125 A JPH09311125 A JP H09311125A JP 8128377 A JP8128377 A JP 8128377A JP 12837796 A JP12837796 A JP 12837796A JP H09311125 A JPH09311125 A JP H09311125A
- Authority
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- Japan
- Prior art keywords
- acoustic impedance
- layered sample
- layer thickness
- sample
- layered
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Length Measuring Devices With Unspecified Measuring Means (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、層状試料の後ろ側
に存在する後側媒質の固有音響インピーダンスを測定す
る音響インピーダンス測定装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic impedance measuring device for measuring the intrinsic acoustic impedance of a rear medium existing behind a layered sample.
【０００２】[0002]
【従来の技術】音響インピーダンスは、媒質中のある平
面における音圧とその面を通る粒子速度との比のことで
ある。音圧と粒子速度は一般には位相が一致しないの
で、音響インピーダンスは複素数となる。音響インピー
ダンスの実数部分を音響抵抗、虚数部分を音響リアクタ
ンスという。Acoustic impedance is the ratio of the sound pressure at a plane in a medium to the particle velocity through that plane. Since acoustic pressure and particle velocity do not generally match in phase, the acoustic impedance is a complex number. The real part of acoustic impedance is called acoustic resistance, and the imaginary part is called acoustic reactance.
【０００３】そして、無限に広がった媒質中の任意の点
における音圧と粒子速度との比を固有音響インピーダン
スという。無損失の平面音波の場合、固有音響インピー
ダンスは、振動数に依らず、媒質の密度ρと音速ｃとの
積ρｃとなる。The ratio of the sound pressure to the particle velocity at an arbitrary point in the medium that spreads infinitely is called the intrinsic acoustic impedance. In the case of a lossless plane sound wave, the intrinsic acoustic impedance is the product ρc of the density ρ of the medium and the sound velocity c, regardless of the frequency.
【０００４】従来、音響インピーダンスの測定は、パル
ス法，振動子アドミッタンス法または音響管法等の方法
で行っていた。例えば振動子アドミッタンス法は、共振
型振動子の振動面を被測定物に接着し、共振周波数付近
で振動子電気端子のアドミッタンスを測定し、アドミッ
タンス円直径及び共振周波数の変化から被測定物の音響
インピーダンスを算出するものである。Conventionally, the measurement of the acoustic impedance has been performed by a method such as a pulse method, a transducer admittance method or an acoustic tube method. For example, in the oscillator admittance method, the vibrating surface of the resonance type oscillator is bonded to the DUT, the admittance of the electrical terminals of the oscillator is measured near the resonance frequency, and the admittance circle diameter and the resonance frequency change The impedance is calculated.
【０００５】[0005]
【発明が解決しようとする課題】従来、密度及び弾性波
速度が既知である層状試料と、この後ろ側に隠れている
後側媒質とから構成されている試料の場合、後側媒質の
音響インピーダンスを測定することができないという問
題があった。Conventionally, in the case of a sample composed of a layered sample whose density and elastic wave velocity are known and a rear medium hidden behind this, the acoustic impedance of the rear medium There was a problem that could not be measured.
【０００６】本発明の目的は、層状試料の後ろ側に隠れ
ている後側媒質の固有音響インピーダンスを測定するこ
とができる音響インピーダンス測定装置を提供すること
にある。An object of the present invention is to provide an acoustic impedance measuring device capable of measuring the intrinsic acoustic impedance of a rear medium hidden behind a layered sample.
【０００７】[0007]
【課題を解決するための手段】本発明の音響インピーダ
ンス測定装置は以下のように構成されている。 （１） 本発明の音響インピーダンス測定装置は、密度
及び弾性波速度が既知である層状試料の後ろ側に密接し
て存在する後側媒質の固有音響インピーダンスを測定す
る音響インピーダンス測定装置において、前記層状試料
の厚さを測定する層厚測定部と、前記層状試料の表面か
ら前記層状試料と後側媒質との積層体の音響インピーダ
ンスを測定する音響インピーダンス測定部と、前記層状
試料の密度及び弾性波速度と測定された層厚及び音響イ
ンピーダンスとから前記後側媒質の固有音響インピーダ
ンスを演算する演算部とを具備してなることを特徴とす
る。 （２） （１）の層厚測定部が、層状試料の表面から送
ったパルスと、層状試料とその後ろ側の後側媒質との界
面からの反射波のパルスが層状試料の表面に到達した時
間差から厚さを求めるものである。 （３） （１）の層厚測定部は、層状試料の表面に設置
された振動子に時間的に変化する周波数を発振させ、振
動子の電流を測定することによって層状試料の厚さを求
める。 （４） （１）に記載の音響インピーダンス測定装置
は、層状試料の表面に設置された共振型振動子に時間的
に変化する周波数を発振させ、この共振型振動子に流れ
る電流を測定することによって音響インピーダンスを測
定するものである。 （５） 主演算部には、層状試料の密度と弾性波速度の
値が格納されている。The acoustic impedance measuring device of the present invention is constructed as follows. (1) The acoustic impedance measuring device of the present invention is an acoustic impedance measuring device for measuring the intrinsic acoustic impedance of a rear medium that is present in close contact with the rear side of a layered sample whose density and elastic wave velocity are known. A layer thickness measuring unit that measures the thickness of the sample, an acoustic impedance measuring unit that measures the acoustic impedance of the laminate of the layered sample and the back medium from the surface of the layered sample, and the density and elastic wave of the layered sample. It is characterized by comprising a calculation unit for calculating the characteristic acoustic impedance of the rear medium from the velocity, the measured layer thickness and the acoustic impedance. (2) The pulse sent from the surface of the layered sample by the layer thickness measurement unit in (1) and the pulse of the reflected wave from the interface between the layered sample and the rear medium behind the layered sample reach the surface of the layered sample. The thickness is calculated from the time difference. (3) The layer thickness measurement unit of (1) obtains the thickness of the layered sample by oscillating a time-varying frequency in the oscillator installed on the surface of the layered sample and measuring the current of the oscillator. . (4) The acoustic impedance measuring device according to (1) oscillates a time-varying frequency in a resonant oscillator installed on the surface of a layered sample, and measures a current flowing through the resonant oscillator. The acoustic impedance is measured by. (5) The values of the density and elastic wave velocity of the layered sample are stored in the main calculation unit.
【０００８】本発明の音響インピーダンス装置は、上記
構成によって以下の作用効果を有する。層状試料（密度
ρ0 、弾性波速度ｃ0 ）と後側媒質（密度ρ1 、弾性波
速度ｃ1 ）とが重ねられて形成されている試料を考え
る。すると、層状試料の固有音響インピーダンスをρ0
ｃ0 、後側媒質の固有音響インピーダンスをρ1 ｃ1 と
表すことができる。そして、層状試料側から見た２層構
造としての音響インピーダンスＺは次式のように表すこ
とができる。The acoustic impedance device of the present invention has the following operational effects due to the above configuration. Consider a sample formed by stacking a layered sample (density ρ 0 , elastic wave velocity c 0 ) and a rear medium (density ρ 1 , elastic wave velocity c 1 ). Then, the intrinsic acoustic impedance of the layered sample is ρ 0
c 0 and the characteristic acoustic impedance of the rear medium can be expressed as ρ 1 c 1 . The acoustic impedance Z as a two-layer structure viewed from the layered sample side can be expressed by the following equation.
【０００９】[0009]
【数１】 [Equation 1]
【００１０】ただし、γは層状試料背面における音圧反
射率、Ｈ0 は層状試料の層厚、λ0は弾性波の波長であ
る。従って、固有音響インピーダンスρ0 ｃ0 が既知の
層状試料の表面に波長λ0を与えて、層状試料の厚さＨ0
と音響インピーダンスＺを測定すれば、（１）式から
音圧反射率γが算出され、さらに、γとρ0 ｃ0 を用い
て（２）式から、側媒質の固有音響インピーダンスρ1
ｃ1 を算出することができる。Here, γ is the sound pressure reflectance on the back surface of the layered sample, H 0 is the layer thickness of the layered sample, and λ 0 is the wavelength of the elastic wave. Therefore, the wavelength λ 0 is given to the surface of the layered sample whose intrinsic acoustic impedance ρ 0 c 0 is known, and the thickness H 0 of the layered sample
And the acoustic impedance Z are measured, the sound pressure reflectance γ is calculated from the equation (1), and the characteristic acoustic impedance ρ 1 of the side medium is calculated from the equation (2) using γ and ρ 0 c 0.
c 1 can be calculated.
【００１１】[0011]
（第１実施形態）図１は、本発明の第１実施形態に係わ
る音響インピーダンス測定装置の概念を示す模式図であ
る。測定対象である試料１０は、密度ρ0 及び弾性波速
度ｃ0 とが既知（つまり層状試料１１の固有音響インピ
ーダンスはρ0 ｃ0 ）である層状試料１１と、この層状
試料の後ろ側に密接して存在し、密度ρ1 及び弾性波密
度ｃ1 とが未知である後側媒質１２とから構成されてい
る。(First Embodiment) FIG. 1 is a schematic diagram showing the concept of an acoustic impedance measuring apparatus according to the first embodiment of the present invention. The sample 10 to be measured is closely attached to the layered sample 11 whose density ρ 0 and elastic wave velocity c 0 are known (that is, the intrinsic acoustic impedance of the layered sample 11 is ρ 0 c 0 ) and the rear side of this layered sample. And the rear medium 12 whose density ρ 1 and elastic wave density c 1 are unknown.
【００１２】そして、層状試料１１の表面に、層状試料
１１の層厚Ｈ0 を測定する層厚測定部２０と、層状試料
１１の表面からみた試料１０の音響インピーダンスＺを
測定する音響インピーダンス測定部２１とが設置されて
いる。層厚測定部２０及び音響インピーダンス測定部２
１の測定結果は、主演算部２２に出力される。主演算部
２２は、測定された層厚Ｈ0 及び音響インピーダンスＺ
と層状試料１１の密度ρ0 及び弾性波速度ｃ0 とから、
後側媒質１２の音響インピーダンスρ1 ｃ1 を演算し、
演算結果を表示部に出力する。そして、表示部２３は、
後側媒質１２の固有音響インピーダンス値ρ1 ｃ1 を表
示する。On the surface of the layered sample 11, a layer thickness measuring section 20 for measuring the layer thickness H 0 of the layered sample 11 and an acoustic impedance measuring section for measuring the acoustic impedance Z of the sample 10 viewed from the surface of the layered sample 11 are measured. 21 and 21 are installed. Layer thickness measuring unit 20 and acoustic impedance measuring unit 2
The measurement result of 1 is output to the main calculation unit 22. The main calculation unit 22 uses the measured layer thickness H 0 and acoustic impedance Z.
From the density ρ 0 and the elastic wave velocity c 0 of the layered sample 11,
The acoustic impedance ρ 1 c 1 of the rear medium 12 is calculated,
The calculation result is output to the display unit. Then, the display unit 23
The characteristic acoustic impedance value ρ 1 c 1 of the rear medium 12 is displayed.
【００１３】次に、層厚測定部の構成の一例を図２に示
す。パルス発生器３１は、送波パルス信号を増幅器３２
と層厚演算器３３とに出力する。増幅器３２は入力され
た送波パルス信号を増幅し、層状試料１１の表面に設置
された振動子３４に出力する。振動子３４は、送受波兼
用であり、送波パルス信号によって振動した後、自動的
に受波可能状態となり、層状試料１１と後側媒質１２と
の界面からの反射波を受波する。振動子３４の受けた受
波パルス信号は、増幅器３５に入力される。増幅器３５
は、受波パルス信号を信号を電圧増幅し、層厚演算器３
３に出力する。そして、層厚演算器３３は、入力された
信号を基に、層状試料１１の層厚Ｈ0 を演算する。FIG. 2 shows an example of the structure of the layer thickness measuring section. The pulse generator 31 amplifies the transmitted pulse signal by an amplifier 32.
And the layer thickness calculator 33. The amplifier 32 amplifies the input transmission pulse signal and outputs it to the vibrator 34 installed on the surface of the layered sample 11. The oscillator 34 is also used for transmitting and receiving waves, and after being oscillated by the transmitted pulse signal, it automatically becomes ready to receive waves and receives reflected waves from the interface between the layered sample 11 and the rear medium 12. The received pulse signal received by the oscillator 34 is input to the amplifier 35. Amplifier 35
Receives the received pulse signal, amplifies the received voltage signal, and calculates the layer thickness calculator 3
Output to 3. Then, the layer thickness calculator 33 calculates the layer thickness H 0 of the layered sample 11 based on the input signal.
【００１４】層厚演算器３３の演算について説明する。
層厚演算器３３は、送波パルスと受波パルスとが入力さ
れた時間差△ｔを検出する。送波パルスと受波パルスの
時間差△ｔは、層状試料を往復する時間である。従っ
て、層状試料１１の弾性波速度ｃ0 は既知であるので層
厚Ｈ0 を、 Ｈ0 ＝ｃ0 ×△ｔ／２ と計算することができる。The calculation of the layer thickness calculator 33 will be described.
The layer thickness calculator 33 detects the time difference Δt at which the transmitted pulse and the received pulse are input. The time difference Δt between the transmitted pulse and the received pulse is the time required to reciprocate through the layered sample. Therefore, since the elastic wave velocity c 0 of the layered sample 11 is known, the layer thickness H 0 can be calculated as H 0 = c 0 × Δt / 2.
【００１５】また、音響インピーダンス測定部の構成の
一例を図３に示す。可変周波数発振器４１は、層状試料
１１の表面に設置された共振型振動子４２と、音響イン
ピーダンス測定器４３に出力する。そして、共振型振動
子４２に流れる電流が電流計４４によって測定され、測
定結果が音響インピーダンス測定器４３に入力される。
そして、音響インピーダンス測定器４３は層状試料１１
の表面からみた音響インピーダンスを演算する。FIG. 3 shows an example of the structure of the acoustic impedance measuring section. The variable frequency oscillator 41 outputs to a resonance type oscillator 42 installed on the surface of the layered sample 11 and an acoustic impedance measuring instrument 43. Then, the current flowing through the resonance type vibrator 42 is measured by the ammeter 44, and the measurement result is input to the acoustic impedance measuring instrument 43.
The acoustic impedance measuring instrument 43 is used for the layered sample 11
Calculate the acoustic impedance seen from the surface of the.
【００１６】この音響インピーダンス測定部による測定
を詳しく説明する。可変周波数発振器４１は、共振型振
動子４２の共振周波数付近で周波数を連続的に変化させ
ながら、一定振幅の電圧を共振型振動子４２に印加す
る。電流計４４は、共振型振動子４２に流れる電流を測
定し、電流値を音響インピーダンス演算部４３に出力す
る。音響インピーダンス演算器４３は、測定された電流
値と共振型振動子４２の電気機械結合定数の情報を基
に、共振振動子４２のアドミッタンスを計算する。そし
て、アドミッタンス円直径及び共振型振動子４２の共振
周波数の変化から、層状試料１１からみた音響インピー
ダンスＺを算出する。The measurement by the acoustic impedance measuring section will be described in detail. The variable frequency oscillator 41 applies a voltage having a constant amplitude to the resonant oscillator 42 while continuously changing the frequency in the vicinity of the resonant frequency of the resonant oscillator 42. The ammeter 44 measures the current flowing through the resonance type vibrator 42 and outputs the current value to the acoustic impedance calculator 43. The acoustic impedance calculator 43 calculates the admittance of the resonant oscillator 42 based on the measured current value and information on the electromechanical coupling constant of the resonant oscillator 42. Then, the acoustic impedance Z viewed from the layered sample 11 is calculated from the change in the admittance circle diameter and the resonance frequency of the resonance type vibrator 42.
【００１７】（第２実施形態）また、第１実施形態の層
厚演算部と異なる層厚演算部の構成を図４に示す。可変
周波数発振器５１は、周波数を連続的に変化させなが
ら、一定振幅の電圧を振動子５２と層厚演算器５３に印
加する。その時、電流計５４は振動子５２に流れる電流
値を測定し、電流値を層厚演算器５３に入力する。そし
て、層厚演算器５３は層状試料１１の層厚Ｈ0 を演算す
る。(Second Embodiment) FIG. 4 shows the structure of a layer thickness calculation unit different from the layer thickness calculation unit of the first embodiment. The variable frequency oscillator 51 applies a voltage of constant amplitude to the oscillator 52 and the layer thickness calculator 53 while continuously changing the frequency. At that time, the ammeter 54 measures the current value flowing through the vibrator 52 and inputs the current value to the layer thickness calculator 53. Then, the layer thickness calculator 53 calculates the layer thickness H 0 of the layered sample 11.
【００１８】この層厚演算部による測定を詳しく説明す
る。層厚演算器５３は、電流計５４から出力された電流
値から、層状試料１１内の厚み共振によって電流振幅が
極大となる複数の周波数を検出し、隣り合う共振周波数
の差△ｆを求める。隣り合う共振周波数の差△ｆの値
は、最小の共振周波数に相当するので、周波数△ｆ，速
度ｃ0 の時の波長の２分の１が層状試料１１の層厚Ｈ0
となる。従って、層状試料１１の弾性波速度ｃ0 と△ｆ
とから、層厚Ｈ0 を、 Ｈ0 ＝ｃ0 ／（２・△ｆ） と算出することができる。本発明は上記実施形態に限定
されるものではなく、本発明の要旨を逸脱しない範囲
で、種々変形して実施することが可能である。The measurement by the layer thickness calculator will be described in detail. The layer thickness calculator 53 detects, from the current value output from the ammeter 54, a plurality of frequencies at which the current amplitude is maximized due to thickness resonance in the layered sample 11, and obtains a difference Δf between adjacent resonance frequencies. Since the value of the difference Δf between the adjacent resonance frequencies corresponds to the minimum resonance frequency, one half of the wavelength at the frequency Δf and the speed c 0 is the layer thickness H 0 of the layered sample 11.
Becomes Therefore, the elastic wave velocities c 0 and Δf of the layered sample 11 are
From this, the layer thickness H 0 can be calculated as H 0 = c 0 / (2 · Δf). The present invention is not limited to the above embodiment, and can be implemented in various modifications without departing from the spirit of the present invention.
【００１９】[0019]
【発明の効果】本発明の音響インピーダンス測定装置
は、層状試料の層厚と層状試料の表面からみた音響イン
ピーダンスとを測定することによって、層状試料の後ろ
側に隠れている後側媒質の固有音響インピーダンスを測
定することができる。The acoustic impedance measuring apparatus of the present invention measures the layer thickness of the layered sample and the acoustic impedance as seen from the surface of the layered sample to obtain the characteristic sound of the rear medium hidden behind the layered sample. Impedance can be measured.
【図１】音響インピーダンス測定装置の概念を示す模式
図。FIG. 1 is a schematic diagram showing the concept of an acoustic impedance measuring device.
【図２】層厚測定部の概念を示す模式図。FIG. 2 is a schematic diagram showing the concept of a layer thickness measurement unit.
【図３】音響インピーダンス測定部の概念を示す模式
図。FIG. 3 is a schematic diagram showing the concept of an acoustic impedance measuring unit.
【図４】層厚測定部の概念を示す模式図。FIG. 4 is a schematic diagram showing the concept of a layer thickness measurement unit.
１０ 試料 １１ 層状試料 １２ 後側媒質 ２０ 層厚測定部 ２１ 音響インピーダンス測定部 ２２ 主演算部 ２３ 表示部 ３１ パルス発生器 ３２ 増幅器 ３３ 層厚演算器 ３４ 振動子 ３５ 増幅器 ４１ 可変周波数発振器 ４２ 共振型振動子 ４３ 音響インピーダンス測定器 ４４ 電流計 ５１ 可変周波数発振器 ５２ 振動子 ５３ 層厚演算器 ５４ 電流計 10 sample 11 layered sample 12 backside medium 20 layer thickness measurement part 21 acoustic impedance measurement part 22 main calculation part 23 display part 31 pulse generator 32 amplifier 33 layer thickness calculator 34 oscillator 35 amplifier 41 variable frequency oscillator 42 resonance type vibration Child 43 Acoustic impedance measuring instrument 44 Ammeter 51 Variable frequency oscillator 52 Transducer 53 Layer thickness calculator 54 Ammeter
Claims (1)
の後ろ側に密接して存在する後側媒質の固有音響インピ
ーダンスを測定する音響インピーダンス測定装置におい
て、 前記層状試料の厚さを測定する層厚測定部と、前記層状
試料の表面から前記層状試料と後側媒質との積層体の音
響インピーダンスを測定する音響インピーダンス測定部
と、前記層状試料の密度及び弾性波速度と測定された層
厚及び音響インピーダンスとから前記後側媒質の固有音
響インピーダンスを演算する演算部とを具備してなるこ
とを特徴とする音響インピーダンス測定装置。1. An acoustic impedance measuring device for measuring the intrinsic acoustic impedance of a rear medium that is in close contact with the rear side of a layered sample of known density and elastic wave velocity, and measures the thickness of the layered sample. A layer thickness measurement unit, an acoustic impedance measurement unit that measures the acoustic impedance of the laminate of the layered sample and the back medium from the surface of the layered sample, and the density and elastic wave velocity of the layered sample and the measured layer thickness And an acoustic impedance measuring device for computing the intrinsic acoustic impedance of the rear medium from the acoustic impedance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8128377A JPH09311125A (en) | 1996-05-23 | 1996-05-23 | Acoustic impedance measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8128377A JPH09311125A (en) | 1996-05-23 | 1996-05-23 | Acoustic impedance measuring device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09311125A true JPH09311125A (en) | 1997-12-02 |
Family
ID=14983323
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8128377A Withdrawn JPH09311125A (en) | 1996-05-23 | 1996-05-23 | Acoustic impedance measuring device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09311125A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006047162A (en) * | 2004-08-06 | 2006-02-16 | Kumamoto Technology & Industry Foundation | Acoustic inspection method and acoustic inspecting apparatus |
| JP2007195743A (en) * | 2006-01-26 | 2007-08-09 | Honda Electronic Co Ltd | Acoustic impedance measuring method and apparatus, and object characteristic evaluation method and apparatus |
| JP2013024620A (en) * | 2011-07-19 | 2013-02-04 | Kofurotsuku Kk | Ultrasonic flowmeter |
| CN114235965A (en) * | 2021-12-20 | 2022-03-25 | 安徽理工大学 | Method, system, medium, equipment and terminal for determining rock damage variable |
-
1996
- 1996-05-23 JP JP8128377A patent/JPH09311125A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006047162A (en) * | 2004-08-06 | 2006-02-16 | Kumamoto Technology & Industry Foundation | Acoustic inspection method and acoustic inspecting apparatus |
| JP4586169B2 (en) * | 2004-08-06 | 2010-11-24 | 一平 鳥越 | Acoustic inspection method and acoustic inspection apparatus |
| JP2007195743A (en) * | 2006-01-26 | 2007-08-09 | Honda Electronic Co Ltd | Acoustic impedance measuring method and apparatus, and object characteristic evaluation method and apparatus |
| JP2013024620A (en) * | 2011-07-19 | 2013-02-04 | Kofurotsuku Kk | Ultrasonic flowmeter |
| CN114235965A (en) * | 2021-12-20 | 2022-03-25 | 安徽理工大学 | Method, system, medium, equipment and terminal for determining rock damage variable |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20030805 |