평균수직응력에 민감한 모재를 가진 기공체의 구성식과 기공생성모델

정현용,Jeong, Hyeon-Yong 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.2

A macroscopic yield criterion for porous solids with pressure-sensitive matrices modeled by Coulomb's yield criterion was obtained by generalizing Gurson's yield criterion with consideration of the hydrostatic yield stresses for a spherical thick-walled shell and by fitting the finite element results of a voided cube. The macroscopic yield criterion is valid for negative mean normal stresses as well as for positive mean normal stresses. From the yield criterion, a plastic potential function for the porous solids was derived either for plastic normality flow or for plastic non-normality flow of pressure- sensitive matrices. In addition, the elastic relation, an evolution equation of the plastic flow stress of the matrices and an evolution equation of the void volume fraction were presented to complete a set of constitutive relations. The set of constitutive relations was implemented into a finite element code ABAQUS to analyze the material behavior of rubber-toughened epoxies. The cavitation and the deformation behavior were analyzed around a crack tip under three-point bending and around notch tips under four-point bending. In the numerical analyses, the cavitation of rubber particles was considered via a stress-controlled nucleation model. The numerical results indicate that a reasonable cavitation zone can be obtained with void nucleation controlled by the macroscopic mean normal stress, and a plastic zone is smaller around a notch tip under compression than under tension. These numerical results agree well with corresponding experimental results on the cavitation and plastic zones.

소화기암에서 조직내 Carcinoembryonic Antigen 측정치와 DNA 배수성과의 관계에 대한 연구

정현용 ( Jeong Hyeon Yong ),김병호 ( Kim Byeong Ho ),성자원 ( Seong Ja Won ),허승식 ( Heo Seung Sig ),이기천 ( Lee Gi Cheon ),이헌영 ( Lee Heon Yeong ),김영건 ( Kim Yeong Geon ),노승무 ( No Seung Mu ),윤완희 ( Yun Wan Hui ),장일성 대한내과학회 1993 대한내과학회지 Vol.44 No.2

연구배경 : 소화기암 조직에서 carcinoembryonic antigne (CEA)의 생산 정도를 측정하고, 종양세포의 생물학적인 악성도를 반영하는 것으로 알려진 DNA 배수성을 분석하여 그들 사이의 관계를 파악하고, 임상상 및 병리조직학적인 특성들과의 상호관계를 알아보자 하였다. 방법 : 절제수술이 가능했던 위암 26예와 결장직장암 14예를 대상으로 조직내의 CEa를 추출한 후 방사선면역 측정법으로 농도를 측정하고 유식세포분석기를 이용하여 DNA 함량과 세포주기분석을 시행하였다. 결과 : 1) 정상 위점막의 CEA 농도는 평균 10.2ng/gm이었고, 위암조직의 CEA치는 평균 42.1ng/gm으로 정상점막에서보다 4배이상 높았으며, 암의 병기가 높을수록 높았다. 2) 정상 대장점막의 CEA치는 평균 27.3ng/gm으로 정상 위점막보다 높았고 (p<0.05), 결장직장암 조직의 CEA 농도는 평균 164.0ng/gm으로 정상 대장점막에서 보다 6배, 위암조직보다 4배정도 높았다(p<0.05). 3) 위암 DNA배수성 유형은 56.0%가 2배성을, 44.1%가 이수성을 보였으며, 결장대장암은 25.0%에서 이수성을 보였고, 75.0%는 2배성암이었다. 소화기암에서 수술 후 병기등의 임상상과 이수성의 빈도는 통계학적으로 유의성이 없었다. 4) 위암 조직의 평균 CEA 농도는 DNA배수성 유형상 이수성인 경우가 86.4ng/gm으로서 2배성암의 14.5ng/gm보다 6배가 높았고 (p<0.05), 결장직장암에서는 이수성암이 244.8ng/gm으로 2배성암보다 (161.7ng/gm)높은 경향을 보였다(p<0.05). 결론 : 소화기암 조직에서 carcinoembryonic antigen의 생산은 DNA배수성 유형상 이수성을 보이는 DNA stemline과 밀접한 관계가 있음을 알게 되었다. 조직내 CEa 농도와 DNA배수성 유형이 예후를 판정하는데 지표로써의 가치여부는 대상환자에 대한 추적이 필요할 것으로 사료된다. Background : This study was performed to obtain additional information about intratumor heterogeneity and prognosis of gastrointestinal cancers, as defined by different DNA stemlines in relation to tumor CEA expression na clinicopathologic characteristics. Methods : In 26 patients with stomach cancer and 14 patients with colorectal cancer, carcinoembryonic antigen concentrations in tissue extracts were measured by radioimmunoassay and the DNA ploidy patterns of same specimens were determined by flow cytometry. Result : 1) Mean tissuc CEA concentrations in the normal gastric mucosa of the patients with stomach cancers was 10.2ng/gm. Tissue CEA concentrations (mean 42.1ng/gm) of stomach cancers were 4 times higher than the normal mucosa (p<0.05), significantly correlated to TNM stages. 2) Tissue CEA concentrations (mean 27.3ng/gm) in the normal colonic mucosa of the patients with colorectal cancers were higher levels than normal gastric mucosa (p<0.05). Tissue CEA concentrations (mean 164.0ng/gm) of colorectal cancers were 6 times higher than the colorectal mucosa` and 4 times higher than stomach cancer`s (p<0.05). 3) The incidence of aneuploid pattern in the stomach cancer was 44.0%, and 25.0% in the colorectal cancers. The incidence of aneuploid cancer was not significantly related to clinicopathologic findings. 4) Tissue CEA concentrations of aneuploid stomach cancers (mean 86.4ng/gm) were 6 times higher than diploid cancers (mean 14.5ng/gm) (p<0.05). Aneuploid colorectal cancers (mean 244.8ng/gm) had higher CEA levels than diploid cancers (mean 161.7ng/gm) (p<0.05). Conclusion : The production of carcinoembryonic antigen in gastrointestinal cancers was significantly correlated with aneuploid DNA stemlines. To estimate prognostic values of tissue CEA concentrations and DNA ploidity, follw up for these patients and further studies should be pursued.

기후변화에 따른 임상분포 변화 및 탄소저장량 예측

정현용(Jeong, Hyeon yong),이우균(Lee, Woo-Kyun),남기준(Nam, Kijun),김문일(Kim, Moonil) 한국기후변화학회 2013 한국기후변화학회지 Vol.4 No.2

카본블랙에 의한 천연고무 물성치와 피로수명 변화에 대한 실험적 연구

김재훈,김영학,정현용,Kim, Jae-Hun,Kim, Yeong-Hak,Jeong, Hyeon-Yong 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.11

The effects of carbon black on the material properties and the fatigue life of the carbon-black filled natural rubbers were investigated. Different kinds of carbon blacks resulted in different fatigue lives, hysteresis, and critical J-values. It was noticed that the hysteresis was inversely proportional to the difference between DBPA and CTAB, and the critical J-value was almost the same regardless of the length of a precrack. In addition, different kinds of carbon blacks resulted in different fracture morphologies, and micro-scale and macro-scale roughnesses. The critical J-value was proportional to the micro-scale roughness. and it seemed relate to the size distribution of carbon black particles. By reviewing all the experimental data. it was finally noticed that the logarithmic value of the fatigue life could be linearly expressed by a multiplication of the critical J-value and the logarithmic value of the hysteresis.

식도암에 의한 위분문부 원격전이의 CT 소견$^1$

유길종,조준식,신경숙,정현용,노승무,손경명,Yu, Gil-Jong,Jo, Jun-Sik,Sin, Gyeong-Suk,Jeong, Hyeon-Yong,No, Seung-Mu,Son, Gyeong-Myeong 대한영상의학회 2002 대한영상의학회지 Vol.47 No.2

목적: 식도암 환자에서 위분문부 원격전이의 전산화단층촬영(CT)소견을 알고자 하였다. 대상과 방법:1994년 6월에서 1999년 5월까지 식도암으로 진단 받은 환자중 위의 분문부종괴로 CT 스캔을 시행하였고, 수술(2명)혹은 내시경을 통한 조직검사(3명)에서 식도의 편평세포암에 의한 원격전이로 진단된 5명의 환자를 대상으로 하였다. CT 소견을 중심으로 병변의위치, 크기, 모양, 동반된 림프절종대 여부를 후향적으로 분석하였다. 5명의 환자 모두 남자였고, 평균 연령은 67.4세(65-75세)였다. 결과: 5예의 식도암 중 4예는 중간부위 식도에,1예는 하부식도에서 발생하였다. 위의 원격전이 병변은 모두 단일성종괴로 분문부에 위치하였고, 원발병변과 떨어져 있었다. CT에서 5예 모두 경계가 잘 그려지며 조영증강이 잘 안 되는 점막하 종괴의 양상으로, 3예는 내장성종괴를, 2예는 외장성종괴를 보였으며, 외장성종괴의 경우 분문에 압흔을 보이는 외부종괴와의 감별이 어려웠다. 위의 전이병변의 크기는 평균 6.7 cm(4.2-8.0 cm)로 모두 원발병변보다 컸으며, 모든 예에서 위점막에 궤양을 보였고,4예는 복부 림프절종대를 동반하였다. 결론: 식도암 환자에서 병기결정이나 추적검사를 위한 CT에서 위의 분문부에서 림프절종대를 동반한 점막하 종괴를 발견할 때, 원격전이의 가능성을 고려해야 한다. Purpose: To assess the CT findings of remote metastasis to the gastric cardia in patients with esophageal carcinoma. Materials and Methods: Among patients with esophageal carcinomas treated between June 1994 and May 1999, five males aged 65-75 (mean, 67.4) years with histologically proven remote metastasis to the gastric cardia from esophageal squamous cell carcinoma, detected at surgery (n=2) or endoscopic biopsy (n=3), underwent CT scanning. We retrospectively evaluated the findings in terms of the location, size and appearance of each lesion and the presence or absence of associated lymphadenopathy. Results: The primary esophageal carcinomas were located in the middle third (n=4) and lower third (n=1) of the esophagus. All five gastric metastases were solitary and occurred in the gastric cardia, and were separated from the primary tumors. CT showed that the metastases ranged in size from 4.2 to 8.0 (mean, 6.7) cm, and all were larger than the primary tumors. All were ulcerated, and in four cases there was associated abdominal lymphadenopathy. They were all well defined, poorly enhanced, submucosal masses that were endogastric in three cases and exogastric in two. The latter were difficult to differentiate from extrinsic masses compressing the gastric cardia. Conclusion: Our results suggest that when a submucosal gastric cardial mass with associated lymphadenopathy is detected by CT during the initial staging or follow-up evaluation of esophageal carcinoma, remote gastric metastasis should be considered

포스터 발표 : 대장 ; 대장암 수술후의 대장선종의 발생양상

나병규 ( Byung Kyu Na ),양현웅 ( Hyeon Uoong Yang ),서숭원 ( Soong Won Seo ),성재규 ( Sung Jae Kyu ),이병석 ( Byung Seok Lee ),정현용 ( Hyun Yong Jeong ) 대한소화기학회 2002 대한소화기학회 춘계학술대회 Vol.2002 No.-

〈목적〉 대장 직장암의 근치수술후 대장내시경 검사를 이용한 추적 검사를 통해 대장 선종의 발생 양상을 분석함으로써 대장직장암 환자에서의 대장선종 발생의 특징을 알아보고자 하였다. 〈방법〉 1998년 3월부터 2001년 2월가지 충남대학교병원에서 대장직장암으로 근치적 절제술을 시행 받은 환자중 수술전가 수술후에 대장내시경을 받았던 130명의 환자를 대상으로 의무기록을 통한 후향적 조사를 하였다. 〈결과〉 남자는 80명, 여자는 50명이었고 평균 연령은 5

Ranitidine 의 소화성궤양치료효과에 대한 임상적연구

김영건(Young Kun Kim),윤성열(Sung Yeul Yoon),정현용(Hyeon Yong Jeong),정선묵(Seon Muk Jeong) 대한소화기학회 1983 대한소화기학회지 Vol.15 No.2

N/A This study was performed to assess the clinical therapeutic effectiveness of anti-histamine agent, ranitidine. The drug was given in the dose of 150mg twice a day to 12 cases of gastric ulcer and 11 cases of duodenal ulcer. Initial diagnosis and follow up observation after 4 weeks, 6 weeks and 8 weeks of treatment were made by the upper G-I endoscopy. The results observed are as followings. 1) The male to female ratio of the subject was about 20:3 and the most prevalent age group was the sixth decade of the life in both the gastric and duodenal ulcer groups. 2) The location of gastric ulcer were 7 cases in body and 5 cases in angle of the stomach and duodenal ulcer were 7 cases in bulb and 4 cases in pyloric area. 3) As for the subjective symptoms, epigastric pain, heart-burning sensation, hunger pain, abdominal discomfort, dyspepsia were experienced, and were relieved after 1 week of treatment in 60 80%, and were completely relieved after 4 weeks of treatment in all cases respecti vely. 4) The cumulative rates of complete healing of the gastric ulcer (12 cases) were 75% (9 cases) after 4 week, 92% (11 cases) after 6weeks, 100%(12 cases) after 8 weeks of treatment, and those of the duodenal ulcer (11 cases) were 91%(10 cases) after 4 weeks, 100%(11 cases) after 6 weeks of treatment. 5) The untoward side effect were not found. In conclusion ranitidine appears to be effective and safe for the treatment of patients with peptic ulcer disease.

정상 하부식도 괄약근압을 보였던 식도이완불능증 2 예

김선문(Sun Moon Kim),나명규(Beung Kyu Na),양현웅(Hyeon Woong Yang),성재규(Jae Kyu Seong),서승원(Seung Weon Seo),이병석(Byung Seok Lee),정현용(Hyun Yong Jeong) 대한소화기기능성질환·운동학회 2002 Journal of Neurogastroenterology and Motility (JNM Vol.8 No.1

Achalasia is an uncommon esophageal motility disorder in which affected patients present with progressive dysphagia. Various causes were known in this disease. Esophageal achalasia is diagnosied by barium esophagogram, endoscopy and esophageal manometry. Treatment of esophageal achasia are pharmacotherapy, pneumatic dilatation, or botulinum toxin injection and surgical therapy. Balloon dilatation is a safe effective first line treatment. We report two cases of achalasia with normal lower esophageal sphincer pressure, typical endoscopic and typical esophagogram findings, which was treated successfully with pneumatic balloon dilatation.(Korean Journal of Gastrointestinal Motility 2002;8:58-62)

만성 염증성 장질환에 대한 임상적 고찰

성재규(Jae Kyu Seong),서승원(Seung Weon Seo),양현웅(Hyeon Woong Yang),이상우(Sang Woo Lee),이승민(Seung Min Lee),이경태(Kyeong Tae Lee),이병석(Byung Seok Lee),임의혁(Euyi Hyeog Im),김남재(Nam Jae Kim),정현용(Hyun Yong Jeong) 대한내과학회 2000 대한내과학회지 Vol.59 No.6

N/A Background : The purpose of this study is to compare the difference of the symptom, sign and laboratory findings among chronic inflammatory bowel diseases such as ulcerative colitis, Crohn's disease and tuberculous colitis in Korea. Methods : We studied in Chungnam National University Hospital from March, 1990 to December, 1998. Seventy-eight cases of ulcerative colitis, fifteen cases of Crohn's disease, and thirty-nine cases of tuberculous colitis were analyzed in terms of age, sex, symptomatology, laboratory findings, radiologic findings and consequence of treatment. Results : The sex ratio of ulcerative colitis, Crohn's disease and tuberculous colitis were 1.17:1, 1.14:1, and 1.29:1, respectively, and the mean age were 39.3, 26.5 and 36.0 years, respectively. The most common symptoms of ulcerative colitis, Crohn's disease and tuberculous colitis were bloody stool, diarrhea, and abdominal pain, respectively. In terms of symptoms and signs, we found that significant differences were bloody stool, diarrhea, and weight loss. Patients with tuberculosis colitis revealed significantly high rate of tuberculous lesion on chest X-ray. Among them, 14(35.9%) of the cases showed active tuberculous lesions. In terms of anatomical distribution of the lesion, the most frequently involved sites of ulcerative colitis, Crohn's disease and tuberculous colitis were rectosigmoid colon. descending colon, and ileocecal valve, respectively. Conclusion : In differential diagnosis of ulcerative colitis, Crohn's disease and tuberculous colitis, we should consider clinical findings, laboratory findings, colonoscopic appearance, histologic assessment, anatomical distribution of the lesions, and treatment course.(Korean J Med 59:618-625, 2000)

대장직장암 수술 후의 대장선종의 발생 양상

나병규 ( Byung Kyu Nah ),김선문 ( Sun Moon Kim ),이엄석 ( Yeum Seok Lee ),양현웅 ( Hyeon Woong Yang ),서승원 ( Seung Weon Seo ),성재규 ( Jae Kyu Sung ),이병석 ( Byung Seok Lee ),정현용 ( Hyun Yong Jeong ) 대한소화기학회 2004 대한소화기학회지 Vol.44 No.4

Background/Aims: After colorectal cancer surgery, colonoscopic surveillance should be done for prevention and early detection of secondary cancer. This study aimed to identify the group with high risk of developing colorectal adenoma after curative surger