자동차용 type II 용기의 가동 중 검사방법에 대한 연구

이종오(Jong-O Lee),지현섭(Hyun-Sup Jee),주노회(No-Hoe Ju),소철호(Cheal Ho So),이종규(Jong-Kyu Lee) 한국가스학회 2011 한국가스학회 학술대회논문집 Vol.2011 No.5

음향방출을 이용한 Type3 용기의 손상 평가 연구

이종오(Jong-O Lee),지현섭(Hyun-Sup Jee),주노회(No-Hoe Ju),소철호(Cheal-Ho So),이종규(Jong-Kyu Lee),김영규(Young-Gyu Kim) 한국가스학회 2012 한국가스학회 학술대회논문집 Vol.2012 No.5

CNG 연료탱크의 내압상승시 발생하는 음향방출 변수들의 분포

지현섭,이종오,주노회,이종규,소철호,Jee, Hyun-Sup,Lee, Jong-O,Ju, No-Hoe,Lee, Jong-Kyu,So, Cheal-Ho 한국재료학회 2011 한국재료학회지 Vol.21 No.11

This is a study on the distribution of acoustic emission parameters during a burst test for a type-II CNG vehicle fuel tank. A resonant AE sensor with a central frequency of 150 kHz was attached to the composite materials in the center of the fuel tank. The pressure was increased from 30 to 100% of the expected burst pressure and was maintained for 10 minutes at each level. Damage at 70% of expected burst pressure occurred by various damage mechanisms including fiber breakage and delamination, while that of below 60% only occurred by matrix crack initiation and growth. The count, duration and rise time of the AE signal at 60% of the expected burst pressure are distributed below 500, 5000 ${\mu}s$ and 300 ${\mu}s$, respectively. Then, at above 70% they increased with pressure by superimposing of individual AE signal generated at a nearby place. These results confirmed that the analysis of the distribution of AE parameters is an effective tool for estimating damage of a CNG fuel tank.

전기저항법에 의한 크리프 손상의 비파괴적 검출

이해무,윤기봉,남승훈,소철호 ( H . M . Lee,K . B . Yoon,S . H . Nahm,C . H . Soh ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.3

As Cr-Mo-V steels have excellent mechanical and creep properties at elevated temperatures, they are extensively used in power plants. However, the steam turbine components are supposed to have suffered material degradation during long-term service at elevated tenperatures. Many efforts have been made to assess the safety and residual life of these components by means of non-destructive methods such as plastic replication, hardness and electric resistance techniques. Recently, a parameter correlating hardness changes during long-term heating to those during creep was introduced and it was named `G parameter`. The electric resistivity as well as hardness are affected by damage accumulation, but there have been no efforts to correlate G parameter to resistivity changes. In this study, relationship between G parameter and changes in electric resistivity was investigated using artificially aged Cr-Mo-V steel. It is well understood that G parameter can be applied to electric resistance techmique.

풍력발전 운영솔루션 개발 및 적용

김영기(Young-Ghi Kim),소철호(Chol-Ho So),변재희(Jaehee Byun),위동윤(Dong-Yun Wi),이충환(Chung-Huan Lee) 대한전기학회 2012 대한전기학회 학술대회 논문집 Vol.2012 No.5

피로시험시 발생하는 음향방출신호를 이용한 Type Ⅱ Gas Cylinder의 손상평가

지현섭(Hyun Sup Jee),이종오(Jong O Lee),주노회(No Hoe Ju),소철호(Cheal Ho So),이종규(Jong Kyu Lee) 한국가스학회 2012 한국가스학회지 Vol.16 No.2

본 연구는 Type Ⅱ가스실린터의 20,000 회 피로시험과 파열시험시 음향방출시험을 병행하여 용기의 손상정도를 평가하고자 하였으며, 실험에 사용된 용기는 결함 크기가 3 mm×3 mm×50 mm (폭×깊이×길이)이고 결함 방향이 용기의 종방향 및 횡방향인 인공결함용기와 건전한 용기 등 세 종류이다. 피로시험시 발생된 음향방출신호는 종방향결함의 경우 전체 신호 중 결함에서 발생된 이벤트의 비율이 50 % 이상이며, 음향방출신호의 위치표정도 매우 정확하게 일치하였다. 또한 파열시험에서는 인공결함용기가 결함 위치에서 에상파열압력보다 낮은 압력으로 파열될거라는 예상과는 달리 인공결함용기의 파열압력은 건전한 용기와 큰 차이가 없었으며, 단지 종방향 인공결함용기의 경우 파열위치가 결함 위치와 근접하게 발생하였다. 이는 종방향 결함의 길이만큼 복합재료의 두께가 얇아지는 효과로 나타나게 되어 금속라이너의 피로반복시 결함 발생과 성장위치에 영향을 미친 것으로 판단된다. This research seeks to evaluate damage on type Ⅱgas cylinder by an acoustic emission test when executing 20000 cycles fatigue test and thereafter burst test. Used gas cylinders in the experimental are three types as follows; one is sound cylinder, others are cylinders which contain longitudinal and transverse artificial defect. The size of artificial defect is a depth of 3 mm, width of 3 mm and length of 50 mm. In the case of the cylinder which artificial defect, unlike the expectation that it will burst in low pressure, the burst pressure of the cylinder did not differ much according to whether or not there were defects. However, when there was longitudinal defect, the location of burst was near the location of defect. This leads to the effect in which the thickness of the composite material becomes thinner according to the length of the longitudinal defect and this is judged to have an effect on the location of initiation and growth of crack in the liner. Also, for the acoustic emission signal, when there is longitudinal defect, the ratio of an event occurring at defect position among overall hits is more than 50 %, and the source location also accords very precisely with defect position.

모혈(募穴)의 탄력(彈力) 상태(狀態) 측정(測定)에 의한 허실(虛實) 진단(診斷) 연구(硏究)

나창수,윤여충,박현철,이동규,최찬헌,장경선,소철호,Na, Chang-Su,Yoon, Yeo-Choong,Park, Hyun-Cheal,Lee, Dong-Kyu,Choi, Chan-Hern,Jang, Kyung-Sun,So, Cheal-Ho 대한침구의학회 2000 대한침구의학회지 Vol.17 No.1

The meridian system is the most essential and basic connecting structure that maintains the vital activities of viscera and bowels by connecting them with each part of body's surface. Doctors can understand the healthy condition, and the region and deficiency-excessiveness of disease by observing the condition of Qi flowing. Deficiency and excessiveness could be differentiated by various symptoms expressed in meridian system. Especially there could be several clues like pain, heat-cold, protuberance-depression, change of color and shine in the line of channel leads to the judgment of deficiency-excessiveness The diagnosis of deficiency and excessiveness can be generalized by quantification of elastic status in skin surface along the meridian system. By comparing data from measurement of elastic condition with those from traditional deficiency and excessiveness, it could be utilized for the development of oriental medicine. All biological activities in the human body are based on meridian system according to the oriental medicine. Also the meridian system is viewed as basic and essential structure connecting internal viscera and each part of body. The areas of expressed channel phenomena are muscle to bone, muscle to muscle and bone to bone. These areas are called depression where meridian system is present and any changing state on those points can be measured. It could be difficult in diagnosing the reaction of meridian system because doctor can depend on his own judgment. Therefore, it is necessary to quantify and indexate channel reactions. To quantify the channel reactions, specially manufactured instrument was used to quantify the protuberance and depression to differentiate the deficiency and excessiveness. The results follow as below; 1. The elastic index measurement by the equipment proved a pattern of agreement showing the values that ranged within standard deviation 0.05kgf/cm throughout the experiment except few cases' measurement in CV-17. 2. To evaluate the state of deficiency & excessiveness of elastic index measurements in frontal point, elastic index measurements in the front paint were compared to the elastic index measured surrounding the point within 2.5 cm. Such result of indexing procedure was closely matched to the concept of palpitation. 3. If the elastic index values in the surrounding front point closely located to the elastic index values in the front point, the judgement on the state of deficiency and excessiveness was delayed. Otherwise, it was judged as deficiency or excessiveness. 4. Out of total 12 cases of comparing the elastic index values to the elastic index values in the surrounding front point, Three to nine front points were judged as either in the state of deficiency or excessiveness. 5. Among the nine front points judged as either in the state of deficiency or excessiveness, Four cases were matched to the electric index measured by EAV that evaluating the internal organs by five different phases. If more clinical cases are accumulated, it is expected to systematically theorize and improve the concept of deficiency and excessiveness in the internal organs using the front point.

고압가스 연료탱크의 손상평가를 위한 음향방출 변수의 분석

지현섭 ( Hyun Sup Jee ),이종오 ( Jong O Lee ),주노회 ( No Hoe Ju ),이종규 ( Jong Kyu Lee ),소철호 ( Cheal Ho So ) 한국복합재료학회 2011 Composites research Vol.24 No.4

본 논문은 자동차용 type II CNG 연료탱크의 손상평가를 위하여 파열시험 중 발생하는 음향방출 변수의 분석에 관한 연구이다. 음향방출 신호의 kaiser effect, felicity effect 및 creep effect의 관찰과 전체 hits에서 진폭 60dB이상의 hits가 차지하는 비율 계산으로 연료탱크의 손상도를 평가할 수 있었으며, 평균 rise time, 평균 진폭 및 평균 initial, reverbration 주파수를 분석함으로써 압력용기의 손상메커니즘을 추정하였다. This paper described analysis of acoustic emission parameter for the damage evaluation of type II vehicle fuel tank during fracture test. The observation of Kaiser effect, Felicity effect and creep effect is the means of damage evaluation method. It is possible to evaluate tank damage by the ratio of hit of over 60 dB and total hit. Damage mechanism of pressure tank can be estimated by analysis of average rise time, average amplitude.

광대역 탐촉자를 이용한 자동차용 CNG 탱크의 음향방출 신호 분석

지현섭(Hyun-Sup Jee),이종오(Jong-O Lee),주노희(No-Hoe Ju),소철호(Cheal Ho So),이종규(Jong-Kyu Lee) 한국비파괴검사학회 2012 한국비파괴검사학회지 Vol.32 No.1

본 연구에서는 광대역(100 kHz - 1 MHz) 탐촉자를 사용하여 자동차용 CNG연료탱크의 파열시험시 발생하는 음향방출신호의 분석을 통해 압력용기의 손상정도를 평가하였다. 압력이 420 bar까지 올라가기 전의 각 단계에서는 Kaiser 효과가 나타나고 creep 효과가 거의 나타나지 않으나, 420 bar 이상 상승시 creep 효과가 현저히 나타남으로써 용기가 손상을 입었다는 것을 알 수 있었으며, 480 bar 압력 상승 단계에서는 Kaiser 효과가 없어졌다. 540 bar의 압력 단계에서 공진형 탐촉자의 경우에서는 480 bar의 압력단계에 비하여 energy나 count 같은 activity가 감소하였으나 광대역 탐촉자의 경우 계속적으로 증가하였다. 또한 rise time이나 주파수 분석을 통해서 복합재료 압력용기의 손상 메카니즘을 관찰하기 위해서는 일반적으로 금속압력용기에서 많이 사용되는 공진형 탐촉자(150 kHz)보다 광대역 탐촉자가 효과적임을 알 수 있었다. This study is damage evaluation for CNG fuel tank during the burst test through the analysis of acoustic emission signals. Kaiser effect until the pressure 420 bar appears, but More than 420 bar by the creep effect appears significantly damaged vessels, and 480 bar pressure, the Kaiser effect of the rising phase was missing. Resonant transducer at 540 bar than 480 bar decreased activity such as energy and count Continually, but increased wideband transducer. In addition, through the rise time or frequency analysis of composite pressure vessels in order to observe the damage mechanisms wideband transducer is more effective than resonant transducer.

인공결함을 가진 CNG 연료탱크의 피로시험시 발생하는 음향방출 신호변수의 분석

지현섭(Hyun Sup Jee),이종오(Jong O Lee),주노희(No Hoe Ju),소철호(Cheal Ho So),이종규(Jong Kyu Lee) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10

This paper seeks to evaluate the acoustic emission test and the damage mechanism of cylinder after 20,000 cycles fatigue tests on type II gas cylinder with artificial defects. We were able to evaluate the damage mechanism through an analysis of acoustic emission parameters, such as the average rise time and average frequency of hits related to events, and the slope of amplitude distribution. According to the results, the average rise time of event signals was 30-90 ㎲ and the rise time of signals due to the growth of matrix crack was shorter than one from the initiation of matrix cracks. The initial and reverberation frequency of signals that occur from to the initiation and growth of matrix cracks were above 100-200 kHz and 150 kHz, respectively. In the amplitude distribution of signals that occurred during fatigue test has a characteristic slope of 0.04, 0.06, and 0.12 is estimated to be from the initiation of matrix crack, growth of liner fatigue crack and growth of matrix crack.