담관 조영술 소견의 변동 : 총담관 담석의 자연소실과 간내담관 가로막에 수반된 다 발성 담석증의 1예 보고

변재영 대한영상의학회 1982 대한영상의학회지 Vol.18 No.4

Disparity among cholangiograms is rarely observed. The causes of disparity include spontaneous disappearance of gall stone, incomplete filling of smaller branch, technical problems, interpretative errors, and overriding of evidence. Spontaneous disappearance of gall stone is rare but has been well documented in both radioloigic and clinical literatures. Recently we have experienced spontaneous disappearance of a large stone in the common bile duct and this forms the basis of the present case report. The patient, 53-year-old female, was admitted on January 18, 1982 to St. Mary's Hospital, Catholic Medical College because of repeated episodes of pain in the epigastrium and the right upper quadrant for the past 2 months. On admission, physical examination revealed tenderness in the epigastrium and the right upper quadrant. Laboratory tests revealed bilirubin 2.2mg/dl and alkaline phosphatase 76.5 KA/dl. A percutaneous transhepatic cholagiogram(PTC) performed 2 days later revealed a large stone measuring 16$\times$26mm in size in the distal CBD. The CBD and CHD proximal to the stone were moderately dilated. Most of the intrahepatic ducts were well delineated without filling defect or evidence of stone. However, the inferior segment of the posterior branch of the right intrahepatic duct (IPRH) was not delineated. The ending of the nonvisualized segment was rather abrupt. The patient suffered severe abdominal pain 2 days after PTC, and was treated with Buscopanⓡ compositum. The attack ceased 20 hours after the onset of colicky abdominal pain. An operation was performed 4 days after PTC. To our surprise there was no stone in the distal CBD. The gallbladder was resected and a T- tube has been placed. A table cholangiogram confirmed disappearance of the stone, but IPRH was agin not opacified except for a short ditance just after bifurcation from the main branch. Eight days after surgery a follow-up T-tube cholangiogram was performed. No residual stone was found in the extrahepatic bile duct. However, IPRH which was not opacifled until then became distinctly visualized demonstrating multiple intra-ductal radiolucent stones. There was a diaphragm-like structure obstructing the lumen and confining the stones located proximally to the site obstructed in the precedent cholangiograms. The radiologic and clinical importances of our observation in this case are four fold: 1. Gall stone up to the diameter of 14$\times$23mm can pass through the papilla spontaneously, 2. Repeat diagnostic imaging is imperative when patient became asymptomatic after severe colicky abdominal pain before the intended operation, 3. Without optimal delineation of intrahepatic biliary radicles, residual stone or stones cannot be excluded in the cholangiograms, 4. And finally, to aviod misdiagnosis a comprehensive knowledge of normal anatomy of cholangiograam is required.

Protein Contact Prediction by Using Information Theory

변재영,이주련 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.9

We develop a novel method for predicting the inter-residue contacts of a protein from evolutionary information obtained from the alignment of multiple sequences. Our method is based on information theory, where we use conditional mutual information so that the spurious correlations coming from indirect effects are removed. The benchmark test shows better performance than the previous method using mutual information does, suggesting the potential of the new method.

DID 기반의 디지털 헌혈증 발급 서비스

변재영,김주희 ( Joohee Kim ),성연주 ( Yeonju Seong ),안현서 ( Hyunseo Ahn ),이은영 ( Eunyoung Lee ),임지연 ( Jiyeon Lim ) 한국정보처리학회 2020 한국정보처리학회 학술대회논문집 Vol.27 No.2

기존 종이 헌혈증의 단점을 보완하기 위해, 블록체인과 DID 를 활용하여 개발한 전자 현혈증 서비스로 헌혈자에게 편리한 헌혈증 사용 및 기부 인터페이스를 제공한다.

기념건축에서 기억의 구상화 전이에 관한 연구 - 천안함기념관 건축계획을 중심으로 -

변재영 한국청소년시설환경학회 2017 청소년시설환경 Vol.15 No.3

인버터식 고효율 네온관용 변압기

변재영,김윤호 한국조명전기설비학회 2002 조명·전기설비학회논문지 Vol.16 No.6

무방향성 규소강판을 사용한 자기식 네온관용 변압기는 내구성이 좋은 반면에 용량에 따른 규소 강판의 무게가 무겁고 외형이 큰 관계로 네온관 설치 작업 시 상당히 불편한 점이 많다. 또한 네온관의 다양한 디스플레이 제어성면에서도 비합리적 이었다. 이를 개선하기 위한 방법으로 네온 트랜스포머의 전원장치 및 2차측 고압 출력부를 고속의 고주파 스위칭 파워 트랜지스터(MOSFET)를 이용하여 상용주파수 60[Hz]를 고속 스위칭 제어를 통하여 20[KHz]의 고주파로 변환시킨후, 네온관을 방전시키기 위한 고전압을 발생시키는 인버터식 네온관용 변압기를 구현하였다. 또한 네온관의 파손이나 누전으로 인한 화재나 인체 감전의 위험을 사전에 방지할 수 있는 보호회로 GFCI(Ground Fault Circuit Interrupter)를 제안 하였다. The conventional neon transformer systems are very bulky and heavy because it consist of leakage type transformers made of silicon steel plates. In addition, it has problems in noise by a neon transformer and in possibilities of fire and electrical shock when neon tubes are destroyed. A protection circuit is designed for all types of neon transformer loaded with one or more neon tubes. Whenever the neon tube fails to be started up, comes to the life end, encounters faults with open-circuits at the output terminals of the neon transformer, the protection circuit will be initiated to avoid more critical hazards. The input of the transformer is automatically cut off when the abnormal condition occurs, preventing waste of no-load power. To improve such problems, in this paper, a new type of neon power supply systems for neon tube is designed and implemented using inverter type circuits and a newly designed lightweight transformer. In the developed neon transformer system, a 60[Hz]power input is converted to 20[KHz]high frequency using half-wave inverters, thereby the transformer reduces its size by 1/5 in volume and 1/10 in weight.

풍력-기상자원지도에 기반한 제주 행원 풍력발전단지 효율성 평가

변재영,강미선,정현숙 한국지구과학회 2013 한국지구과학회지 Vol.34 No.7

This study evaluates wind farm efficiency at Haengwon in Jeju Island. The actual energy production at Haengwon wind farm is compared with the estimated energy production based on Korean wind map which is developed at the National Institute of Meteorological Research/KMA. The validation of wind map at Gujwa located near the Haengwon wind farm shows that the wind speed is overestimated. The diurnal variation of wind speed shows a maximum value in the afternoon due to the effect of sea-land breeze. The ratio of the actual energy production at Haengwon wind farm and the estimated energy production based on the Korean wind map is 24.8%, while the distribution of energy frequency is similar each other. The difference of energy production is caused by mechanical error of the turbine and the overestimation of the simulated wind map. This study will contribute to the repowering of turbines for improving the efficiency of wind farm in the future. 풍력 발전단지의 효율성 평가를 위하여 풍력-기상자원지도로부터 이론적 잠재량을 계산하고 행원 발전단지 발전량과 비교하였다. 풍력-기상자원지도는 기상청 국립기상연구소에서 개발된 1 km 해상도 자료를 이용하였다. 풍력-기상자원지도와 AWS(구좌) 풍속의 비교 검증 결과는 풍속이 과대 모의되었으며, 행원 발전단지 풍속의 일 변동성은 해륙풍의 영향으로 오후에 최대가 되는 일 변동 특성을 보였다. 풍력-기상자원지도로부터 산출된 발전량과 행원 발전단지발전량의 비율은 24.8%이나, 발전량 빈도수 분포 형태는 유사하였다. 발전량 차이의 원인은 터빈의 기계적 오류, 풍력-기상자원지도 풍속의 과대 모의에 기인한 것으로 생각된다. 본 연구는 향후의 발전단지 효율성 증가를 위한 터빈의 재배치에 기여 할 것이다.

트래픽 손실율 예측을 통한 신경망 UPC 알고리즘에 관한 연구 ( Study on a Neural Network UPC Algorithm Using Traffic Loss Rate Prediction )

변재영,이영주,정석진,김영철 대한전자공학회 1998 대한전자공학회 학술대회 Vol.1998 No.7

압연 방향을 적용한 자체 진단형 고효율 네온관용 변압기

변재영,김윤호 한국조명전기설비학회 2003 조명·전기설비학회논문지 Vol.17 No.1

본 논문에서는 네온 변압기의 효율을 높이기 위하여 주 자속과 누설 자속의 흐름을 분석하고, 이에 따른 압연 방향과 주 자속과의 방향을 최대한 일치 시켜서 자속에 의한 손실을 최소화 하고 역율을 향상시킨 고효율의 네온관용 변압기를 제시 하였다. 그리고 정격 부하시, 단락시 및 무부하시의 각각의 자속 분포를 해석하고 이를 응용하여 부하측 이상 발생시 즉시 전원이 차단될 수 있는 전자식 차단 장치를 개발부착 하였다. 즉 네온관의 파손이나 누전으로 인한 화재나 인체 감전의 위험을 사전에 방지 할 수 있는 전자식 보호 기능을 내장한 자체 진단형의 무방향성 코어의 압연 방향성을 고려한 고효율의 네온관용 변압기를 구현하였다. In this paper, a high efficiency leakage transformer for neon tube is developed to improve its power factor, to reduce its core loss and weight by using a technique of shape optimization and grain direction of non-oriented silicon steel strip. A protection circuit is designed for all types of neon transformer loaded with one or more neon tubes. Whenever the neon tube fails to be started up or comes to the life end, or encounters faults with open-circuits at the output terminals of the neon transformer, the electronic type protection circuit will be initiated to avoid more critical hazards. These neon transformers need a electronic type protection circuit to prevent from current stresses on circuit components by neon tube fail. The input of the transformer is automatically cut on when the abnormal condition occurs, preventing waste of no-load power.

Friction Characteristics of Aluminized Polyester Fabric under Dry- and Water- Lubricated Conditions

변재영,오케추쿠 나에메카 니콜라스,이은숙,박진규,최원식 한국트라이볼로지학회 2019 한국윤활학회지(윤활학회지) Vol.35 No.6

Materials made from plastics are increasingly utilized in constructing greenhouses and setting up shield structures. Polyester fabrics have a wide range of use in horticulture and other fields of agriculture. They are utilized as a greenhouse cover and also help in combating intense climate variation in the field. Over time, these fabrics may experience friction against other surfaces. Owing to this, the surface framework of the material degenerates. This study examines the frictional characteristics of aluminized polyester fabric in both dry- and water-lubricated environments under changing applied loads and sliding speeds. Friction experiments are performed at room temperature by employing a pin on a disk. The experiments reveal that the friction coefficient decreases with increase in applied load in both dry sliding and water-lubricated environment. However, the friction coefficient decreases more under the water-lubricated setting than in the dry state. At the maximum applied load, the highest friction coefficient is discovered in the dry state with a range of 0.282 to 0.237, whereas a friction coefficient of 0.229 to 0.189 is observed in the water-lubricated state. Additionally, it is observed that the friction coefficient increases with an increase in sliding speed under both experimental environments. The examination of specimen surfaces reveals that the abrasion is minor in the water-lubricated setting compared with that in the dry state.

수도권 도시기상관측망 운영 현황

변재영,박향숙,이동원,박문수,채정훈,하종철 한국기상학회 2019 한국기상학회 학술대회 논문집 Vol.2019 No.10