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이해철(H.C. Lee),이준서(J.S.Lee),차경옥(K.O.Cha) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1999 No.11_1
Setting the channel-switching phase of automobile control mufflers in low-speed region is effective measures to improve low-speed torque. A muffler sensing exhaust-gas pressure has been developed to solve this problem. This muffler reduces exhaust noise in a pair of tailpipes by generating interference through a reverse-phasing process. This reduces exhaust noise makes it possible to set the muffler's channel-switching phase in the low-speed region.<br/>
[진동·소음부문] 회전요소 베어링 상황감시를 위한 음향-진동 신호의 고차 통계해석
이해철(H.C.Lee),이준서(J.S.Lee),차경옥(K.O.Cha) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper present a study on the application of sound pressure and vibration signals to detect the presence of defects in a rolling element bearing using a statistical analysis method. The well established statistical parameters such as the crest factor and the distribution of moments including kurtosis and skewless are utilized in this study. In addition. other statistical parameters derived from the beta distribution function are also used. A comparison study on the performance of the different types of parameter used is also performed. The statistical analysis is used because of its simplicity and quick computation. Under ideal conditions. the statistical method can be used to identify the different types of defect present in the bearing. In addition. the results also reveal that there is no significant advantages in using the beta function parameters when compared to using kurtosis and the crest factor for detecting and identifying defects in rolling element bearings from both sound and vibration signals.
이해철(H.C.Lee),이민호(M.H.Lee),이준서(J.S.Lee),한경(K.Han),양진승(J.S.Yang),차경옥(K.O.Cha) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1
In automobile exhaust system, internal pulsating pressure and shell vibration greatly affect the exhaust noise and the surface radiated noise. This noise is emitted from the tailpipe outlet and the muffler outer wall due to the pulsation of the exhaust gas pressure. This paper describes an analytical study of these characteristics as influenced by exhaust system structure. An exhaust system simulator was used for generating the pressure pulsation. The relationship between pulsating pressure and exhaust noise was analyzed. The relationship between shell vibration and surface radiated noise was also identified by finding FRF.<br/>
비기능성 뇌하수체 종양에 연관된 항이뇨호르몬 분비이상 증후군
이준철 ( Jun Chul Lee ),권기현 ( Ki Hyun Kwon ),이인석 ( Ihn Suk Lee ),김윤정 ( Yun Jeung Kim ),정사라 ( Sa Rah Jeong ),김설영 ( Seul Young Kim ),구본정 ( Bon Jeong Ku ) 대한내과학회 2007 대한내과학회지 Vol.72 No.3
We present a case of severe hyponatremia in a 64-year-old man who had a pituitary tumor. He had nausea and recurrent vomiting with a severe headache, and was admitted to Chungnam National University Hospital for further evaluation. On physical examination, he was alert, and had bitemporal hemianopsia. There was no indication of dehydration or edema. Laboratory data showed a serum sodium level of 126 mEq/L, plasma osmolality of 259 mOsm/kg, and urinary osmolality of 544 mOsm/kg. The plasma argipressin level was 2.88 pg/mL, despite marked hyposmolality. Otherwise, pituitary function was normal. Brain magnetic resonance imaging showed a pituitary macroadenoma measuring 25×16×13 mm and no visible normal pituitary stalk or gland in the sella turcica. After the adenomectomy, the serum sodium level maintained normal without treatment. Histology showed the presence of a pituitary adenoma. These findings indicate that a non-functioning pituitary tumor may cause the exaggerated secretion of argipressin, resulting in inappropriate antidiuretic hormone syndrome. (Korean J Med 72:315-321, 2007)
이준철(J.C Lee),이정원(J.W Lee),조정현(J.H Cho),김승호(S.H Kim) 한국정보과학회 2005 한국정보과학회 학술발표논문집 Vol.32 No.2
본 논문에서는 감시 시스템 내에서 검출된 객체에 대해 정확한 특징벡터를 추출하기 위한 그림자 제거(shadow casting)방법을 제안한다. 그림자에 의해 부정확한 특징벡터를 가지게 되는 객체는 동일한 객체임에도 불구하고 서로 다른 객체로 인식하는 잘못된 결과를 가져온다. 이러한 문제점을 해결하기 위해 추출된 객체의 경계선(edge)의 수직 히스토그램과 그림자의 방향성을 사용하여 그림자를 제거한다.
이준서(J.S.Lee),이해철(H.C.Lee),이민호(M.H.Lee),박명규(M.K.Park),차경옥(K.O.Cha) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_1
The pulsating pressure waves are composed of fundamental frequency and higher order harmonics in exhaust pipe of engines. The nonlinearity in exhaust pipe is caused by their interactions. The error which is between prediction and measurement is induced by the nonlinearity. We can not explain this phenomenon using linear acoustic theory which is existing theory. So power spectrum which was used in linear theory is not useful. Bispectrum and bicoherence functions which are a higher order spectrum are applicable to explain this phenomenon. This paper proposes a nonlinear effect of pulsating pressure waves. The phenomenon proposed here is identified by using of cross-higher order spectrum and quadratic Volterra model.<br/>
붕규산유리 및 비정질 붕소강 섬유를 혼입한 콘크리트의 역학적 성능 및 중성자 차폐성능 평가
이준철(Jun-Cheol Lee) 한국건설순환자원학회 2016 한국건설순환자원학회 논문집 Vol.4 No.3
본 연구에서는 붕규산 유리와 비정질 붕소강 섬유를 혼입한 콘크리트의 역학적 성능 및 중성자 차폐성능을 평가하였다. 잔골재를 붕규산 유리로 치환한 콘크리트와 비정질 붕소강 섬유를 보강한 콘크리트를 제조하여 압축강도, 정탄성계수, 압축인성, 휨강도, 휨인성, 중성자 차폐성능을 평가하였다. 실험결과, Plain 콘크리트와 대비하여 붕규산 유리를 혼입한 콘크리트의 경우 압축강도 및 휨강도는 저하되었으나, 중성자 차폐성능은 향상되는 것으로 나타났다. 비정질 붕소강 섬유를 혼입한 콘크리트의 경우 Plain 콘크리트와 대비하여 압축인성 및 휨인성이 증진되었으며 중성자 차폐성능도 향상되는 것으로 나타났다. In this study, the mechanical properties and the neutron shielding rate of concrete with the borosilicate glass and the amorphous boron steel fiber were investigated. The measures of this investigation includes air contents, slump loss, compressive strength, static modulus of elasticity, compressive toughness, flexural strength, flexure toughness and neutron shielding rate. As a result, the neutron shielding rate of the concrete with borosilicate glasses increased even though the compressive strength and flexural strength decreased in comparison with that of plain concrete. Also, the mechanical toughness and the neutron shielding rate of the concrete with amorphous boron steel fiber increased in comparison with that of plain concrete.
회분식 반응기에서 음식물쓰레기를 이용한 바이오에탄올 생산
이준철(Jun Cheol Lee),김재형(Jae Hyung Kim),박홍선(Hong Sun Park),박대원(Dae Won Pak) 大韓環境工學會 2010 대한환경공학회지 Vol.32 No.6
유기성 폐기물인 음식물쓰레기를 이용하여 유용한 에너지원인 바이오에탄올을 생산하고자 하였으며, 에탄올 생산 균주는 Saccharomyces cerevisiae를 이용하였다. 음식물쓰레기의 당화를 위하여 carbohydrase와 glucoamylase 효소를 이용한 결과 carbohydrase가 glucoamylase보다 당화효율이 우수하였으며, carbohydrase 이용시 건조 음식물쓰레기 기준 glucose 생산량 0.63g/g-TS을 얻을 수 있었다. 에탄올 생산은 동시당화발효에서 0.44g/L·hr, 분리당화발효가 0.27g/L·hr이었다. In the present study, bioethanol was produced using batch style reactor from food wastes which has organic characteristics. Pretreatment was required to reduce its particle size and produce fermentable sugar. Two different enzymes such as carbohydrase and gulcoamylase were tested for saccharification of food waste. The efficiency of carbohydrase saccharification (0.63g/g-TS) has shown higher than glucoamylase saccharification(0.42g/g-TS). Saccharomyces cerevisiae produced bioethanol via separate hydrolysis & fermentation (SHF) method and simultaneous saccharification fermentation (SSF) method. The production amount of bioethanol was 0.27 g/L·hr for SHF and 0.44 g/L·hr for SSF.