내연기관 흡기 계통의 Plenum Chamber의 유동 해석 모델에 관한 연구

윤건식,윤영환,우석근 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-

In this paper, the simulation models were examined to represent the flow through the plenum chamber in the intake system of MPI spark ignition engine. The constant-pressure perfect-mixing model or branch model which had been devised originally to represent the flow through the manifold branch system was tested. The constant-volume model or tank model also applied and the results were compared with those of the branch model. The prediction accuracies showed no remarkable differences between two models. Therefore, both models would be applicable successfully to represent the flows at the plenum chamber.

低蛋白食餌로 成長한 흰쥐에 四鹽化炭素의 投與가 肝損傷에 미치는 影響

尹鐘國,李芳子,金碩煥 啓明大學校 生活科學硏究所 1983 科學論集 Vol.9 No.-

低蛋白 食餌로 成長한 흰쥐에 CCl₄投與가 肝損傷에 미치는 影響을 觀察할 目的으로 Sprague-Dowley 系 흰주 암컷을 飼料 100g 當 methionine 5㎎, L-lysine은 1㎎을 8% casein 食餌에 添加한 食餌條件을 低蛋白 食餌群으로 하고 15% casein에 低蛋白 食餌群과 同一한 量의 metheionine 및 lysine을 添加한 것을 標準蛋白 食餌群으로 하여 7週間 飼育한 후 體重 100g 當 50% CCl₄의 0.13㎖을 1日 1回씩 2일동안 皮下로 注射하였으며, 이때 對照群은 olive oil만 CCl₄投與群과 같은 요령으로 投與한 뒤 實驗動物을 屠殺한 후 實驗하여 다음과 같은 成績을 얻었다. 1) 低蛋白 및 標準蛋白 食餌로 7週동안 成長하는 동안 두 群사이의 體重 增加率은 有意한 差는 볼 수 없었으며 成長後 最終 臟器 무게도 兩群間에 有意한 差를 볼 수 없었다. 한편 CCl₄投與後 대체적으로 臟器(肝臟, 脾臟, 腎臟, 心臟)의 무게가 增加되었으며, 이 中 肝의 무게 增加率이 가장 큰 것으로 나타났다. 또한 低蛋白 및 標準蛋白 食餌群間에 CCl₄投與로 因한 臟器 무게의 變動은 대체적으로 低蛋白 食餌群이 標準蛋白 食餌群보다 적게 나타나는 樣狀을 보였으며 特히 다른 臟器에 비해 肝의 무게 增加率이 低蛋白食餌群에서 低下되었다. 2) CCl₄投與로 因한 肝細胞의 蛋白質 含量이 모두 減少되는 傾向을 보였으나 有意性은 없었으며 低蛋白 食餌群이 標準蛋白 食群보다 肝細胞質의 蛋白質 減少率이 低下되었다. 3) CCl₄投與後 標準蛋白 食餌群에서 血淸 GPT, GDA 活性은 顯著히 增加되었으며 低蛋白 食餌群의 血淸 GPT 活性은 有意한 增加를 보였으나(P<0.001) 標準食餌群보다는 增加率이 低下 되었고 血淸 GDA 活性의 變種은 低蛋白 食餌群에서는 對照群에 比해서 약간 增加되는 傾向을 보였으나 有意性은 없었으며 標準食餌群보다는 그 增加率이 低下됨을 알 수 있었다. 한편 CCl₄投與후 肝組織의 GPT活性値가 低蛋白 및 標準蛋白食餌群의 兩群 모두 減少되는 傾向을 보였으나 意義있는 變種은 아니었으며 兩群사이의 減少率은 有意한 差를 볼 수 없었다. 또한 CCl₄投與로 因한 肝 GDA活性의 變動은 標準蛋白 食餌群에서는 약간 增加되는 傾向을 보였으나 意義있는 變動은 볼 수 없었으며 低蛋白 食餌群에서는 有意한 增加를 보였다. (P<0.001) 以上 實驗成績을 綜合하여 볼 때 低蛋白食餌 條件으로 成長한 흰쥐가 標準蛋白 食餌群으로 成長한 흰쥐에 비하여 CCl₄로 因한 肝損傷이 적게 나타나는 것으로 생각된다. The effect of hepatic injury produced by carbon tetrachloride (CCl₄: 0.65㎖/㎏; S.C.) was studied on female rats receiving a low protein-high carbohydrate (8% casein) and a standard protein-low carbohydrate (15% casein) diet, supplemented with 5㎎ of methionine and 1㎎ of lysine in both diets. The weights of internal organs, i. e., heart liver, kidney and spleen, were generally elevated by the injection of CCl₄ to female rate fed low or standard protein diet. Especially the increase of liver weight was the highest whereas the liver weight increment of rats fed standard protein diet was greater than those fed low protein diet by the injection of CCl₄. In general, the other orgains weights of rats fed low protein diet were a tendency to remain stable as compared with those of rats fed standard protein diet during the acute intoxication of CCl₄. The injection of CCl₄ showed a greater degree of serum GPT, GDA activities in animals fed the standard protein diet as against those fed a low protein diet. On the other hand, the low degree of hepatic protein content was a tendency to reduce in rats fed low protein diet as against those fed a standard protein diet. In conclusion, the effect of low protein intake in increasing the degree of hepatic damage does not seem to be present when CCl₄ is the injuring agent.

일부 지하철 근로자와 소방공무원의 직무 스트레스 요인 비교

윤석환,최숙정,신동훈,정인성,하정숙 대한산업의학회 2007 대한직업환경의학회지 Vol.19 No.3

역도 용상 Clean 동작에 관한 연구

윤정환,이석구 한국스포츠리서치 2004 한국 스포츠 리서치 Vol.15 No.4

In this study elite male university athletes lifts the weight 95% of MBW for each athletes, For the foot pressure measurement systems were used to analyze changes in kinetic variables related to Clean movements, and the following conclusions were obtained. 1. For the Clean movement among all subjects, the maximum foot pressures were 1.6 and 1.9 times greater than the sum of one's own weight and the barbells weight during the first pull and lock-out, respectively. 2. Pressure was mostly distributed at the toes and the front part of the sole in exerting strength actively as in Pull movement and it was evenly distributed in the entire sole in bearing load passively as in lock-out movement.

하수슬러지를 이용한 복합소재 개발연구

연규석,권윤환,유근우,김남길,김동준,이윤수 강원대학교 부설 석재복합신소재 제품연구센터 2002 석재연 논문집 Vol.7 No.-

본 연구는 하수 종말 처리에 의해 발생되는 하수 슬러지를 잔 골재(경량골재)로 사용하여, 폴리머 콘크리트를 제조하여 그 때의 역학적 성질에 대하여 검토하였다. 하수 슬러지는 5일간 110±5℃에서 수분함량 0.1%미만으로 건조한 후 파쇄하여 No.4∼No. 200 번체의 잔골재 표준 시방서 기준에 부합되도록 사용하였다. Pellet는 보통 회전pan에서 만드나, 본 실험에서는 수동으로 제조하였다. 제조한 하수 슬러지 경량 골재는 평균 겉보기 비중은 1.58(g/㎤), 단위용적중량은 1.98(t/㎥)으로 KS F 2534의 경량골재의 절건비중과 단위용적에 따른 분류에 의하면 중위급(medium weight) 경량골재에 속하는 것으로 측정되었다. 또한 잔 골재 중 하수 슬러지 경량 골재를 0%, 5%, 10%, 15%, 20%, 25%, 30%로 치환하여 그때의 압축, 휨, 인장강도를 측정하였다. 그 결과 하수 슬러지의 증가에 따라 강도 감소를 보였으나, 일반 경량콘크리트 제조 또는 단열용 콘크리트 블록 제조에 사용이 가능하다고 사료된다. 그러므로 앞으로 건조수축, 크리이프 특성 및 내구성에 관한 연구가 더욱 심도 있게 이루어져야 폐자원인 하수 슬러지를 이용한 건자재의 개발이 가능하리라 판단된다. In this study, the polymer concrete was produced by using the lightweight aggregate that had been manufactured using the sewage sludge and its physical properties were experimentally examined. Experimental results show that when the portion of sewage sludge lightweight aggregate in the fine aggregate increases, slump values decreases. Also, the compressive, the flexural and the tensile strengths decrease when the portion of sewage sludge lightweight aggregate increases. Although its strengths decreases, the sewage sludge lightweight fine aggregates is thought to be used for construction materials.

알코올성 췌장염 환자에서 CYP2E1 유전자형의 다형성

김일환,염윤기,채석,권준택,김형기,박상흠 순천향의학연구소 2001 Journal of Soonchunhyang Medical Science Vol.7 No.2

Cytochrome P4502E1(CYP2E1) is inducible by ethyl alcohol and activates procarcinogenic N-nitrosodimethylamine(NDMA), benzene, urethane and other lower molecular weight compound. CYP2E1 is also involved in metabolism of certain drugs, for example, alcohol, acetaminophen, tamoxifen, theophylline, flouorinated anesthetics, and chlorozoxazone. CYP2E1 activity was shown to be polymorphically distributed in humans and has been suggested to play a role in hepatocellular carcinoma and alcoholic related disorders. Although genetic predispodition to alcoholism and alcoholic liver disease has been reported, genetic susceptibility to alcoholic pancreatitis is still a matter of debate. The aims of this study were to investigate the allelic frequency of CYP2E1 Rsa I polymorphism in Koreans with alcoholic pancreatitis patients. We investigated the frequency distribution of CYP2E1 Rsa I polymorphism in 212 unrelated healthy Koreans and 64 alcoholic pancreatitis patients. Detection of the CYP2E1 alleles was performed by polymerase chain reaction and restriction fragment length analysis. The genomic DNA was isolated from peripheral blood with conventional phenol: chloroforn extraction method. The allelic frequencies of c1 and c2 in healty volunteers were 0.85 and 0.15, respectively. The allelic frequencies of c1 and c2 in alcoholic pancreatitis patients were 0.8 and 0.2, respectively. The rare type (c2/c2) of CYP2E1 Rsa I polymorphism was 0.005 and 0.031 (p<0.001) in healthy volunteers and alcoholic pancreatitis patients, respectively. However, the CYP2E1 genotype showed no significant relation to the alcoholic pancreatitis patients. It was suggested that the risk of alcoholic pancreatitis diagnosed clinically seem to be not associated with the CYP2E1 genotype.

SJO¨GREN'S SYNDROME 환자에게 즉시 임프란트 술식을 행한 치험례

최정환,손동석,이지연,이윤서,안선희,이재목 대한악안면성형재건외과학회 2000 Maxillofacial Plastic Reconstructive Surgery Vol.22 No.5

The old edentulous patients experience xerostomia commonly. They have considerable difficulty in wearing tissue-supported prosthesis and high risk rate of caries. One of them is Sj□gren's syndrome patient. Sj□gren's syndrome is a chronic inflammatory autoimmune disorder that results in a lymphocyte-mediated destruction of exocrine glands. We planned to place implants immediately after extraction in this case of autoimmune disease. The advantages of immediate implant placement include considerable decrease in time from tooth extraction to placement of the final prosthesis, fewer surgical procedures, and better acceptance of the overall treatment plan. We present a case of Sj□gren's syndrome patient treated with immediate implant placement & immediate loading in anterior region and immediate implant placement in posterior region.

낙상으로 인한 좌심실 파열 후 생존한 환자 1례

배택환,김행재,정윤석,김준식,조준필,이철주 대한응급의학회 1995 대한응급의학회지 Vol.6 No.1

Blunt or nonpenetrating chest injuries are common after motor vehicle accidents or falls. Blunt injury to the heart ranges from contusion to rupture. Cardiac rupture, however, is un-common and associated with a very high mortality rate ; left ventricular rupture due to falling is even more rare. We experienced a case of left ventricular rupture of the heart caused by a fall, which the patient survived. A 63-year-old man fell off a ladder and presented with hypotension from left hemothorax and pericardial tamponade. The hemothorax was relieved via an emergency closed thoracostomy but dyspnea and hypotension continued. And so, echocardio-graphy was done and pericardial tamponade was detected. Emergency left thoracotomy was done to repair the rupture site. We believe that patients with cardiac rupture who reach the hospital alive can often be saved by prompt diagnosis and immediate surgical treatment.

실드터널 시공시의 지표 구조물의 침하 억제 대책에 관한 연구

임종철,윤이환,박이근,고호성,홍석우 釜山大學校生産技術硏究所 1999 生産技術硏究所論文集 Vol.56 No.-

연약지반 터널 굴차시 실드공법은 근접 구조물 안전에 유용한 공법이다. 하지만 실드 터널 공법은 터널 주변 지반의 변형을 최소화 할 수 있는 장점을 가지는 반면 테일 보이드(Tail Void)에 그라우트된 주입재가 경화되기 전에 발생하는 지반 변형은 피하기 어렵다. 본 연구에서는 테일 보이드로 인한 인접 구조물의 침하를 억제하는 방법중 하나인 마이크로파일(micropile)의 영향을 모형실험을 통하여 규명하였다. 기초적인 실험 결과로써 마이크로파일 보강시 마이크로파일의 효과적인 설치방향과 침하 억제비를 밝혔다. In soft ground tunneling, shield method is very good for safety of neighboring structures. Although shield tunnel method has the merits to minimize the deformation of ground around tunnel, ground deformations occurred until the material grouted in tail void hardens are inevitable. In this study, the effects of micropile used as one method to restrain the settlement of neighboring structures by the tail void are studied by laboratory model tests. As a basic test result, the effective direction of micropile and the restraint rate of settlement by micropile reinforcement are known.

휴대폰 케이스 가공업체에서 발생한 은피증 1예

탁기홍,윤석환,이미영,신동훈,정인성 대한산업의학회 2006 대한직업환경의학회지 Vol.18 No.4

배경: 은피증은 은의 피부 침착에 의해서 생기는 질환으로, 만성적인 노출에 의해 생기며, 치료법이 없는 영구적인 질병이다. 은의 흡입에 의한 은피증의 보고는 아주 드물며, 우리나라에는 현재까지 관련 보고가 없었다. 이에 휴대폰 도장제의 은 흡입에 의한 은피증을 보고하고자 한다. 증례: 30세 남자근로자로 5년 전부터 휴대폰 부품조립 및 도장업체에서 EMI부서와 가스켓부서에서 전자기파 차단제를 스프레이 도장하는 작업을 하였고, 3년 전부터 서서히 발생한 얼굴과 몸의 회색 및 회청색 피부색 변화를 주소로 내원하였다. 전자기파 차단제는 은, 구리, 용제들로 구성되어 있었다. 피부 조직 검사에서 에크린 한선 기저판(basal lamina)에 미세하고 둥근 흑갈색 과립들이 관찰되어 은피증의 소견을 보였으며, 작업중 노출된 은 흡입에 의한 직업성 은피증으로 진단하였다. 킬레이트 치료는 도움 되지 않으며, 노출 중단 및 자외선 차단 등의 보존적인 방법을 사용하고 있다. 고찰: 은피증은 은의 복용, 흡입, 접촉에 의해 발생한다. 본 증례에서는 은피증을 원인으로 작업시의 은 노출 이외의 은 노출을 발견할 수 없었다. 그러므로, 직업성 은피증으로 사료되며, 은의 첨가제에 의해 은피증이 발생 할 수 있음을 보여준다. 현재 전자기파 차단의 용도로 은과 은 화합물의 사용이 계속되고 있으므로, 이에 대한 대책이 필요하다고 본다. 적절한 치료법이 없기 때문에, 예 방이 가장 중요하며, 보호구 착용, 작업환경 개선, 산업 안전보건교육이 필요하다. Background: Skin contact with, and the breathing in of air containing silver compounds can occur in the workplace. Occupational exposure to silver and its compounds is mainly via airborne dust, metal fumes, and mists of solutions containing silver compounds. Argyria results from increased serum silver levels and the deposition of silver-containing particles in the dermis and mucous membranes. The author reports a patient with generalized argyria, who worked on the manufacture of cellular phone cases. Case report: The patient was a 30 year-old male, with extensive blue-gray discoloration of the whole body, especially sun-exposed area, of 3 years duration. He had been exposed to silver in the processing of EMI for the past 4 years and gaskets for 1 year. EMI is the process by which the internal electromagnetic wave in cellular phone cases are shielded, and gaskets play an important role in shielding the electric clashes between electronic circuits, as well as increasing the durability of cellular phone cases to impact. EMI had been processed manually but this was changed to automatic spraying by robots in 2003. On physical examination, the patient had diffuse blue-gray discoloration of the skin, which was most prominent in the sun-exposed areas of his face, neck and V of the chest. Histopathological examination of a punch biopsy specimen from the posterior neck revealed fine, minute, round, and brown-black granules deposited in the basement membrane zone surrounding the eccrine glands. The laboratory findings were positive for hepatitis B antigen, with a serum silver concentration of 150.3 ppb. From this evidence, he was diagnosed with argyria due to silver exposure. Discussion: The author reports a case of occupational systemic argyria due to inhalation exposure of silver compounds.