NaOH 수용액내에서 Al 및 Al - Sn 합금 전극의 전기화학적 거동에 관한 연구

이경근,김광범 ( Kyung Keun Lee,Kwang Bum Kim ) 한국부식방식학회 1998 Corrosion Science and Technology Vol.27 No.2

15세 여아에서 발생한 췌장의 비기능성 신경내분비종양 - 1예 보고 -

이경근,박진영,Lee, Kyung-Keun,Park, Jin-Young 대한소아외과학회 2009 소아외과 Vol.15 No.2

We report a case of nonfunctioning neuroendocrine tumor of the pancreas in a 15-year-old girl who presented with back pain. On physical examination, there was mild tenderness in the left upper quadrant of the abdomen. The patient had no pancreatic hormone-associated symptoms. An abdominal ultrasonography showed a well-demarcated hypervascular solid mass with calcification in the tail of the pancreas. An abdominal computed tomography scan showed a $6{\times}5cm$ sized well-encapsulated enhancing solid mass with cystic component in the tail of the pancreas. Distal pancreatectomy was performed. Pathology revealed awelldifferentiated nonfunctioning low grade malignant neuroendocrine tumor of the pancreas. The postoperative course was uneventful.

950℃ 순수헬륨 분위기에서 크리프 파단된 Alloy 617의 미세구조적 고찰

이경근,정수진,김대종,김우곤,박지연,김동진,Lee, Gyeong-Geun,Jung, Su-Jin,Kim, Dae-Jong,Kim, Woo-Gon,Park, Ji-Yeon,Kim, Dong-Jin 한국재료학회 2011 한국재료학회지 Vol.21 No.11

The very high temperature gas reactor (VHTR) is one of the next generation nuclear reactors for its safety, long-term stability, and proliferation-resistance. The high operating temperature of over 800$^{\circ}C$ enables various applications with high energy efficiency. Heat is transferred from the primary helium loop to the secondary helium loop through the intermediate heat exchanger (IHX). The IHX material requires creep resistance, oxidation resistance, and corrosion resistance in a helium environment at high operating temperatures. A Ni-based superalloy such as Alloy 617 is considered as a primary candidate material for the intermediate heat exchanger. In this study, the microstructures of Alloy 617 crept in pure helium and air environments at 950$^{\circ}C$ were observed. The rupture time in helium was shorter than that in air under small applied stresses. As the exposure time increased, the thickness of outer oxide layer of the specimens clearly increased but delaminated after a long creep time. The depth of the carbide-depleted zone was rather high in the specimens under high applied stress. The reason was elucidated by the comparison between the ruptured region and grip region of the samples. It is considered that decarburization caused by minor gas impurities in a helium environment caused the reduction in creep rupture time.

Aumann-Sharpley 가격에 의한 공통 제조원가의 배분 - 상대적 이익 기여도를 중심으로-

이경근,Lee, Kyung-Keun 대한산업공학회 1989 산업공학 Vol.2 No.2

We study the joint cost allocation based on the book profit producing power of the output through the A-S price mechanism. We show what part of the A-S book profit is allocated to the joint cost and what part is allocated to the variable total book profit of the short-run book profit function. Also we compare some other classical joint cost allocation methods with this A-S price method.

Sn-4.0wt%Ag-0.5wt%Cu 솔더 접합계면의 강도특성과 미세파괴거동에 대한 In-situ관찰

이경근,최은근,추용호,김진수,이병수,안행근,Lee, Kyung-Keun,Choi, Eun-Geun,Chu, Yong-Ho,Kim, Jin-Soo,Lee, Byung-Soo,Ahn, Haeng-Keun 한국재료학회 2008 한국재료학회지 Vol.18 No.1

The micro-structural changes, strength characteristics, and micro-fractural behaviors at the joint interface between a Sn-4.0wt%Ag-0.5wt%Cu solder ball and UBM treated by isothermal aging are reported. From the reflow process for the joint interface, a small amount of intermetallic compound was formed. With an increase in the isothermal aging time, the type and amount of the intermetallic compound changed. The interface without an isothermal treatment showed a ductile fracture. However, with an increase in the aging time, a brittle fracture occurred on the interface due mainly to the increase in the size of the intermetallic compounds and voids. As a result, a drastic degradation in the shear strength was observed. From a microshear test by a scanning electron microscope, the generation of micro-cracks was initiated from the voids at the joint interface. They propagated along the same interface, resulting in coalescence with neighboring cracks into larger cracks. With an increase in the aging time, the generation of the micro-structural cracks was enhanced and the degree of propagation also accelerated.

멀티스케일 모델링을 이용한 압력용기강의 조사손상 정량예측

이경근,권준현,Lee, Gyeong-Geun,Kwon, Junhyun 한국압력기기공학회 2014 한국압력기기공학회 논문집 Vol.10 No.1

In this work, an integrated model including molecular dynamics and chemical rate theory was implemented to calculate the growth of point defect clusters(PDC) and copper-rich precipitates(CRP) which could change the mechanical properties of reactor pressure vessel(RPV) steels in a nuclear power plant. A number of time-dependent differential equations were established and numerically integrated to estimate the evolution of irradiation defects. The calculation showed that the concentration of the vacancies was higher than that of the self-interstitial atoms. The higher concentration of vacancies induced a formation of the CRPs in the later stage. The size of the CRPs was used to estimate the mechanical property changes in RPV steels, as is the same case with the PDCs. The calculation results were compared with the measured values of yield strength change and Charpy V-notch transition temperature shift, which were obtained from the surveillance test data of Korean light water reactors(LWRs). The estimated values were in fair agreement with the experimental results in spite of the uncertainty of the modeling parameters.

소아에서 변형 Sistrunk술식을 적용한 갑상성 설관낭종의 치료성적

이경근,정풍만,Lee, Kyeong-Geun,Jung, Poong-Man 대한소아외과학회 2001 소아외과 Vol.7 No.2

Thyroglossal duct cyst is ectodermal remnant, which may develop along the line of descent of the thyroid gland from the foramen cecum of the tongue to the pyramidal lobe of the thyroid gland. Meticulous dissection of the cyst and duct, along with the body of the hyoid bone is necessary to avoid recurrence. Eighty-one patients with thyroglossal duct cyst treated at Hanyang University Hospital between January 1980 and December 2000 were reviewed to determine the incidence and to analyze the result of management. The male-to-female ratio was 1.4:1(47:34) with a male preponderance. They are most commonly present at 3-8years(54.2 %) of age, but rarely present at infancy. The most common symptom was a painless midline neck mass(76.5 %, 62cases). Eighty-one patients underwent modified Sistrunk operation without evidence of recurrence. Eight-nine percent(72 cases) of these lesions were located between thyroid substance and hyoid bone, and 11 %(9 cases) were above the hyoid bone. There were 22 infected cysts(27.2 %). The Sistrunk operation is a gold standard for treating the thyroglossal duct cysts. For best results in thyroglossal duct cyst surgery, one should make every effort to remove the cyst intact in continuity with the body of the hyoid bone. In our institute, Sistrunk operation modified by the authors showed a good result.

소아에서 발생하는 선천성 두경부 기형

이경근,정풍만,Lee, Kyeong-Geun,Jung, Poong-Man 대한소아외과학회 2001 소아외과 Vol.7 No.1

Congenital anomalies of the head and neck region such as preauricular sinus and skin tag, thyroglossal duct cyst, branchial anomaly, cystic hygroma and dermoid cyst are common in pediatric population. It is important for pediatricians and pediatric surgeons to be familiar with the embryology and the anatomical characteristic of these lesions in order to diagnose and treat them properly. Three hundred and nineteen patients with congenital head and neck anomalies treated at Hanyang University Hospital between 1980 and 1999 were reviewed to determine the relative frequency of the anomalies and to analyze the method of management. Eight-four (25.1 %) of 335 lesions were preauricular sinus and skin tag, 81 (24.2 %) were thyroglossal duct cyst, 81 (24.2 %) branchial anomaly, 58 (17.3 %) cystic hygroma and 31 were (9.2 %) dermoid cyst. The male-to-female ratio was 1.4:1. Thyroglossal duct cyst most commonly present at 3-5years, however branchial anomalies commonly are diagnosed in children younger than 1 year. Preauricular sinus showed familial tendency in three patients and was bilateral is 33.8 %. Most head and neck anomalies in children have specific clinical and anatomical characterics. A careful history and physical examination is very useful for diagnosis and proper management. Experienced pediatric surgeons should do the initial surgery since the recurrence rate after incomplete surgical excision can be high.

유동가속부식에 대한 통계적 모델링 해석방법 개발: 유속, 온도, pH 및 Cr 함량의 효과

이경근,이은희,김성우,김동진,Lee, Gyeong-Geun,Lee, Eun Hee,Kim, Sung-Woo,Kim, Dong-Jin 한국압력기기공학회 2016 한국압력기기공학회 논문집 Vol.12 No.2

Flow accelerated corrosion (FAC) of the carbon steel piping has been a significant problem in nuclear power plants. FAC occurs under certain hydrodynamic, environmental, and material conditions, and extensive research into the factors of FAC has been conducted. The basic process of FAC is now relatively well understood; however, a full mechanistic model has not yet been established. Recently, the Korea Atomic Energy Research Institute (KAERI) has built a large experiment loop system for FAC. To produce significant experimental results using this system, the factors affecting on FAC should be analyzed quantitatively, and a model needs to be developed. In this work, a statistical modeling methodology to develop an empirical model is described in detail, and a preliminary model is suggested. Firstly, FAC data were collected from the research literature in Japan and the results of domestic experiments. The flow rate, water temperature, pH at room temperature, and the Cr content are selected as major factors, and nonlinear regression is used to find the best fit of the available data. An iterative procedure between suggesting and evaluating a model is used until an optimum model is obtained. The developed model gives the FAC rate comparable to the measured FAC rate. The developed model is going to be refined using additional laboratory data in the future.

전이동 78예 및 전이 피부 부속기 28예에 대한 임상 경험

이경근,김민수,정풍만,Lee, Kyeong-Geun,Kim, Min-Soo,Jung, Poong-Man 대한소아외과학회 2003 소아외과 Vol.9 No.1

Preauricular sinus and preauricular skin tag are common childhood congenital anomalies. It is important for the pediatric surgeon to be familiar with the embryology and differentiation of head and neck structure to accurately diagnose and treat these lesions. Seventy eight patients with preauricular sinus and twenty-eight with preauricular skin tag treated in the Department of Pediatric Surgery at Hanyang University Hospital from January 1981 to May 2002 were reviewed to determine relative frequency, clinical classification and appropriate treatment. The male to female ratio of preauricular sinus was 1:1.2, and preauricular skin tag was 1:1. The most commonly presenting age of sinus and skin tag was before 5 year (62.8%) and before 1 year (53.6%). Twenty nine of 78 cases of preauricular sinuses were on the left, 25 on the right and 24 bilateral. Signs of infection were seen in 73.0% of patients with preauricular sinus at operation. Only 31.3% of lesions were infected in patients less than one year of age, but 89.5% between 3-5 years and 100% between 5-8 years. Cartilage was present in five patients with preauricular skin tag. Although re-operation due to wound infection was necessary in four cases, no recurrences were found. The preauricular sinus is a common anomaly in childhood, and has had a relatively high recurrence rate. But most of the recurrences were due to incomplete resection because of combined infection. Initial proper diagnosis and early operation are very important. Identification of the exact anatomical location of sinus tract is necessary because total excision of the lesions including those tracts is the only way to prevent recurrence.