페라이틱 강 배관내의 원주방향 표면균열 평가를 위한 새로운 Z-Factor의 개발

최영환,정연기,이정배,Choi, Yeong-Hwan,Chung, Yeon-Ki,Lee, Jeong-Bae,WilkowsKi, Gery 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.6

The purpose of this paper is to develop new Z-Factors to evaluate the behavior of circumferential surface crack in ferritic steel piping including base metal and Submerged Arc Weld(SAW) metal in nuclear power plant. The Z-factor is a load multiplier to convert plastic load to elasto-plastic load. However the current Z-Factor is a load multiplier to convert plastic load to elasto-plastic load. However the current Z-Factor gives too conservative results. In this study, a J-estimation method, SC.TNP method, which is based on GE/EPRI expression, is used to develop new Z-Factors. The desirabilities of both the SC.TNP mehtod and the new Z-Factors are examined using the previous experimental results for the circumferential surface crack in ferritic steel pippings. The results are as follows ; (1) The SC.TNP mehtod is good for describing the circumferential surface crack behavior in farritic steel pipings, while the well-known R6 mehtod and DPFAD method give too conservative results. (2) The ASME-Z-Factor method using nwe Z-Factors well predicts the behavior of circumferential surface crack in ferritic steel pipings including base emtal and SAW metal.

원전사고 평가를 위한 원전 사건유형분석 시스템(ETAS) 개발

최영환,김영미,Choi, Young Hwan,Kim, Young Mi 한국압력기기공학회 2009 한국압력기기공학회 논문집 Vol.5 No.2

In this study, Event Type Analysis System (ETAS) is developed for the accident evaluation in nuclear power plant. The ETAS system can be used in supporting regulator and/or operator under event situation in nuclear power plants. The ETAS system can categorize the all transient events to 3 categories such as Down-2000, Down-2173, and Slow Fluctuation. We develop the program structure for ETAS system and web-based ETAS system. The ETAS system will be used as sub module of Knowledge-Based Event Evaluation Network (K-EvENT) which is developing for the against the accident in nuclear power plants.

밀양지역 들깨품종별 잎의 아미노산 조성 및 향기성분 비교

최영환,이영근,Choi Young-Whan,Lee Young-Guen 한국생명과학회 2004 생명과학회지 Vol.14 No.6

우리나라 들깻잎의 주산지인 밀양지역에서 재배하고 있는 4종의 품질 특성을 조사하고자 아미노산과 휘발성 향 성분을 분석하여 비교하였다. 단백질구성아미노산에서 주요 아미노산은 aspartic acid, glutamic acid, glycine, alanine, arginine, 및 threonine 등 이었고, 그 외에 lysine, leucine, isoleucine 등도 다소 검출되었으나, tyrosine과 함황아미노산인 cysteine과 methionine의 함량이 가장 적 게 나타났으며, 유리 아미노산은 4종 모두에서 약34종이 검출되었다. 그리고 유리아미노산의 조성과 단백질구성아미노산의 조성에서 품종간의 차이는 거의 없는 것으로 나타났다. 들깻잎의 휘발성 향기성분을 GC-MSD로 분석한 결과, 잎들깨1호는 52종, 엽실들깨는 48종, 그리고 밀양9호와 YCPL은 47종이 분리되어 검출되었다. 깻잎의 휘발성 화합물중에서 가장 많은 함량으로 검출된 perilla ketone은 엽실들깨 $551.42\;{\mu}g/g$, 잎들깨1호 $301.59\;{\mu}g/g$, YCPL $187.00\;{\mu}g/g$, 그리고 밀양9호는 $145.75\;{\mu}g/g$이었으며, 그 외 3-hexen-1-ol, trans-2-hexenal, $\beta-caryophyllene$ 그리고 $\alpha-farnesene$등이 검출되었으나 이 화합물들의 함량은 $20\;{\mu}g/g$을 초과하지 않았다. The present investigation was carried out to determine the qualitative difference between 4 varieties of perilla leaves cultivated Miryang area, particularly focusing on the amino acid composition and flavor compounds. Aspartic acid, glutamic acid, glycine, alanine, arginine, and threonine were the major amino acids, and tyrosine and cysteine and methionine containing sulfur were detected as little amount in protein of all perilla leaves. All perilla leaves contained about 34 kinds of free amino acids, and the major free amino acids were same as the protein bound amino acids. However, no significant difference among 4 varieties of perilla leaves was observed in the profiles of protein bound and free amino acids composition. Flavor compounds analyzed by GC-MSD following to extraction of flavor by SDE (Simultaneous Steam Distillation-Extraction) were detected as 51 kinds from 'Leafy perilla 1', 47 kinds from 'Yupsil perilla', 46 kinds from 'Miryang 9' and 'YCPL. The major volatile compound was perilla ketone, its concentration was $145.75\;{\mu}g/g$ in 'Miryang 9', $187.00\;{\mu}g/g$ in 'YCPL', $301.59\;{\mu}g/g$ in 'Leafy perilla l' and $551.42\;{\mu}g/g$ in 'Yupsil perilla', but the other flavor compounds, 3-hexen-l-ol, trans-2-hexenal, $\beta-caryophyllene,\;\alpha-farnesene$ and etc, were less than $20\;{\mu}g/g$.

원전 사고처리 지원시스템(ECAS) 개발

최영환,김영미,고한옥,Choi, Young Hwan,Kim, Yopng Mi,Ko, Han Ok 한국압력기기공학회 2009 한국압력기기공학회 논문집 Vol.5 No.2

In this study, Event Corrective Action Supporting System (ECAS) is developed for the accident evaluation in nuclear power plant. The ECAS system can be used in supporting regulator and/or operator under event situation in nuclear power plants. The ECAS system consists of 5 modules including failure location module, failure analysis module, failure integrity evaluation module, system vulnerability evaluation module, and reporting and operating experience feedback module. The ECAS system will be used as sub module of Knowledge-Based Event Evaluation Network (K-EvENT) which is developing for the against the accident in nuclear power plants.

원주방향균열이 존재하는 원전 배관계통의 파괴거동에 관한 실험적 연구(I) - 직관부에서의 균열거동 평가 -

최영환,박윤원,Choi, Young-Hwan,Park, Youn-Won,Wilkowski, Gery 대한기계학회 1999 大韓機械學會論文集A Vol.23 No.7

The purpose of this study is to investigate experimentally the effects of both seismic loading and crack length on the fracture behavior of piping system with a circumferential crack in nuclear power plants. The experiments were performed using both large scale piping system facility and 4 points bending test machine under PWR operating conditions. The difference in the load carrying capacities between cracked piping and non-cracked piping was also investigated using the results from experiments and numerical calculations. The results obtained from the experiments and estimation are as follows : (1) The safety margin under seismic loading is larger than those under quasi static loading or simple cyclic loading. (2) There was no significant effect of crack length on tincture behavior of piping system with both a surface crack and a through-wall crack. (3) The load carrying capacity in cracked piping was reduced by factors of 7 to 46 compared to non-cracked piping.

호중구 감소된 급성 림프구성 백혈병환아에서 발생한 Pneumocystis carinii 폐렴 1례

최영환,민기식,김종완,김광남,유기양,Choi, Young Hwan,Min, Ki Sik,Kim, Jong Wan,Kim, Kwang Nam,Ryoo, Ki Yang 대한소아감염학회 1997 Pediatric Infection and Vaccine Vol.4 No.1

Pneumocystis carinii pneumonia mainly occurs in immunocompromised patients and it is also known of major cause of death in children with acute lymphoblastic leukemia. After consolidation chemotherapy, acute lymphoblastic leukemia children is developed Pneumocystis carinii pneumonia frequently no an opportunistic infection but there were no controlled studies which have been performed to evaluate the usefulness of corticosteroid in Pneumocystis carinii pneumonia with acute lymphoblastic leukemia. We experienced a case of Pneumocystis carinii pneumonia in acute lymphoblastic leukemia with febrile neutropenic 6 years old girl. She was treated with trimethoprim-sulfamethoxazole and prednisone. We report this case with brief review of related literature.

콘크리트 충전 각형강관 기둥의 폭두께비 제한에 관한 연구

최영환,Choi, Young-Hwan 한국강구조학회 2012 韓國鋼構造學會 論文集 Vol.24 No.4

구조적 우수성이 입증된 콘크리트 충전 강관 (CFT) 시스템은 폭두께비가 큰 강관을 사용할 때 더욱 경제적인 설계가 될 수 있다. 하지만, 현재 국내외의 규준에서는 CFT에 사용할 수 있는 강관의 폭두께비를 제한하고 있어 건설 재료를 보다 더 효율적으로 활용할 수 있는 가능성을 미리 차단하고 있다. 본 연구에서는 폭두께비 60, 70, 80, 90, 100를 갖는 각형 단주 CFT에 대해 압축실험을 실시하여 CFT에서의 좌굴 후 내력을 확인하였고 기존의 규준에서 제시한 폭두께비 제한치를 완화한 식을 제시하였다. The concrete-filled steel tube (CFT) that has an excellent performance can be more economically used when the steel tube has a large width-to-thickness ratio. However, the international provisions such as American Institute of Steel Construction (AISC) limit the use of a slender plate in CFT members, resulting in a less optimal use of CFT. This study verifies the post buckling strength of CFT columns through the experimental program for Hollow Steel Sections (HSS) and CFTs with a with-to-thickness ratio ranged 60 to 100. The study also proposes a relaxed limitations of with-to-thickness ratio compared to the one specified in the current standards.

고강도 콘크리트를 사용한 각형 CFT 기둥의 축력-모멘트 상관곡선

최영환,김강수,최성모,이상섭,Choi, Young Hwan,Kim, Kang Su,Choi, Sung Mo,Lee, Sangsup 한국강구조학회 2007 韓國鋼構造學會 論文集 Vol.19 No.6

본 논문은 55 MPa 이하 강도의 콘크리트를 사용한 CFT 기둥에 대한 P-M 상관곡선을 제안한 선행연구의 후속연구로서, 2005 AISC에서 새롭게 포함된 55 MPa 이상의 고강도 콘크리트를 사용한 정방형 CFT 기둥의 P-M 설계식을 제안하였다. 선행연구에서 제안한 개념을 적용하여 고강도 콘크리트를 사용한 CFT에서의 최대모멘트와 최대모멘트시의 압축력을 구하기 위해 강관의 폭두께비(b/t)와 강관의 항복강도에 대한 콘크리트의 상대강도(fck/Fy)를 중요 변수로 총 36개의 대상단면을 선정하여 Fiber Analysis를 통한 변수해석을 수행하였다. 강관의 응력-변형율 관계는 완전탄소성으로 가정하였고 콘크리트는 고강도 콘크리트에 적용가능한 Sakino의 모델을 이용하였다. 변수해석으로부터 얻어진 결과로부터 상기의 두 변수를 이용하여 고강도 콘크리트를 사용한 각형 CFT 기둥의 설계에 쉽게 사용할 수 있는 설계식을 제안하였다. 기존의 실험결과와 비교한 결과 본 논문에서 제시하는 방법은, 2005 AISC에서 제시하는 방법에 비해 보다 더 쉽고 간단하게 사용될 수 있는 것으로 나타났다. In this study, a new design equation was presented for square CFTs with high-strength concrete subjected to axial compression and bending. In a previous study, a design equation for square CFTs with normal strength concrete was proposed. A parametric study by fiber analysis was performed taking the width-to-thickness ratio (b/t) and the relative concrete strength to the yield strength of the steel tube (fck/Fy) as the main parameters of this study to determine the maximum moment and the axial load at the maximum moment. A new constitutive model for concrete was adopted for fiber analysis in order to take into account the effect of high-strength concrete. The results of the parametric study were embedded into the method which was presented in the previous study to formulate a new design equation that can be easily used for estimating the strength of square CFTs with high-strength concrete.

소아에서 고혈압, 번갈 다음증, 다뇨증, 및 저칼륨증을 유발한 레닌-분비성 윌름스 종양(Wilms' Tumor)

최영환,이남혁,김상윤,곽정식,Choi, Young-Whan,Lee, Nam-Hyuk,Kim, Sang-Youn,Kwak, Jung-Sik 대한소아외과학회 1997 소아외과 Vol.3 No.1

A 3-year-old boy with a Wilms' tumor had unusually severe hypertension, polydipsia, polyuria and hypokalemia. Physical examination on admission was unremarkable except for the presence of a smooth, firm mass in the right abdomen. Computerized tomography showed a tumor occupying the upper two thirds of the right kidney. Plasma renin activity and aldosterone concentration were markedly elevated, 37.7 mg/ml/hour(normal in supine position 0.15-2.33 mg/ml/hour) and 120.1 ng/dL(normal in supine position 1 to 16 ng/dL), respectively. Hypertension varied from 150/90 mmHg to 240/180 mmHg, and was not effectively controlled by antihypertensive drugs. Right nephrectomy was performed on the sixth hospital day. At laparatomy, there was no evidence of mechenical compression of the renal artery by the tumor. The tumor, about 8 cm in diameter, was confined to the renal capsule without involvement of the renal blood vessels at the hilum. Histopathology was Wilms' tumor of favorable histology. On electron microscopy, tumor cells contained intracytoplasmic electron dense secreting graules, suggesting the possibility of renin secreting tumor cells. Shortly after nephrectomy, signs and symptoms were relieved dramatically, and plasma renin activity and aldosterone concentration were also decreased to normal.

국내 가압경수형 원자로에 대한 가압열충격 기준온도 평가

최영환,박정순,정명조,Choi, Young Hwan,Park, Jeong Soon,Jhung, Myung Jo 한국압력기기공학회 2010 한국압력기기공학회 논문집 Vol.6 No.2

The evaluation method for the failure frequency of reactor vessel under pressurized thermal shock(PTS) is developed using probabilistic fracture mechanics. The probabilistic reactor integrity evaluation code, named R-PIE code, is developed. The validity and uncertainty of the R-PIE code is investigated. The reactor failure frequencies under PTS for Kori-1 nuclear power plant and other type of domestic nuclear power plants are evaluated. The reference PTS temperature for domestic nuclear power plants is obtained for the rule making against PTS failure.