Parallel Finite Element Analysis System Based on Domain Decomposition Method Bridges

이준성,염곡 강이,이은철,이양창,Lee, Joon-Seong,Shioya, Ryuji,Lee, Eun-Chul,Lee, Yang-Chang Computational Structural Engineering Institute of 2009 한국전산구조공학회논문집 Vol.22 No.1

본 논문에서는 대규모 3차원 구조해석에 필요한 병렬 유한요소해석을 위한 영역분할법의 적용에 대해 묘사하였다. 영역분할법을 사용한 병렬 유한요소법 시스템을 개발하였다. 절점 생성시, 절점들간의 거리가 특정절점에서의 공간함수와 같아지면 절점이 생성되어 진다. 이 절점공간함수는 퍼지지식처리에 의해 조절되어 진다. 기본적인 요소생성은 데로우니 삼각화 기법을 적용하였다. 자동요소생성 시스템을 이용한 영역분할법은 3차원 해석에 큰 도움이 된다. 공간함수와 유사하게 절점들간의 유한요소해석을 위한 병렬 수치 알고리즘으로서 영역분할법을 전체의 해석영역을 완전히 여러 개의 작은 영역으로 겹치지 않게 나누는 공역구배인 반복적 솔버와 결합시켰다. 개발된 시스템의 효용성에 대한 성능을 몇 가지 예를 통해 제시하였다. This paper describes an application of domain decomposition method for parallel finite element analysis which is required to large scale 3D structural analysis. A parallel finite element method system which adopts a domain decomposition method is developed. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay triangulation method is introduced as a basic tool for element generation. Domain decomposition method using automatic mesh generation system holds great benefits for 3D analyses. Aa parallel numerical algorithm for the finite element analyses, domain decomposition method was combined with an iterative solver, i.e. the conjugate gradient(CG) method where a whole analysis domain is fictitiously divided into a number of subdomains without overlapping. Practical performance of the present system are demonstrated through several examples.

듀얼 에너지 CT의 가상 단색 영상을 이용한 영상 교정 팬텀과 금속 인공음영에 관한 연구

이준성,이승훈,박주경,이선영,김진기,Lee, Jun seong,Lee, Seung hoon,Park, Ju gyung,Lee, Sun young,Kim, Jin ki 대한방사선치료학회 2017 대한방사선치료학회지 Vol.29 No.1

목 적: 이중선원 듀얼에너지 CT(DS-DECT)의 가상 단색 영상을 이용해서 영상의 질 향상과 선량학적 영향에 대한 방사선치료계획 이용의 유용성을 평가하고자 한다. 대상 및 방법: DS-DECT를 이용하여 듀얼에너지(80/Sn 140 kVp)와 싱글에너지(120 kVp) 영상을 획득하였다. 영상 교정 팬텀 실험을 위해서 40-140 keV 범위로 단색 영상을 재구성했다. 선량 측정용 고체물등가팬텀 연구에서는 64, 69, 88, 105 keV 단색 영상을 선택했다. 스테인리스 스틸을 포함한 고체물등가팬텀에 $10{\times}10cm^2$ 조사야, SSD 100 cm, 10 MV 광자선, 100 MU 조사선량, 단일빔으로 치료계획을 수립하였다. 방사선량측면도 자료는 중심축에 위치한 4개의 지점에서 구했다. 싱글에너지 CT에서 획득한 다색 영상을 기준영상으로 하고, 가상 단색 영상의 선량학적 결과를 분석하였다. 결 과: 낮은 단색 에너지 수치에서 평균 감약이 증가했다. 7개의 물질 중에서 Teflon이 에너지 의존성이 가장 컸고, 10 keV 수치 상승으로 CT number가 평균 2.48 % 감소했다. 저밀도 공기에서는 단색 에너지에 대한 에너지 의존성이 없었다. Polystyrene, Acrylic은 70 keV 이상에서 안정한 CT number를 나타내었다. CT-ED 변환 곡선은 80 keV 단색 영상과 120 kVp 다색 영상이 비슷하였다. 단색 영상의 에너지가 증가할수록 금속의 식별 능력이 향상되었다. 줄무늬 인공음영은 105 keV 단색 영상에서 높은 감소를 보였지만, 여전히 남아 있었다. 다색 영상과 비교하여 각 영상에 따른 방사선치료계획의 선량학적 차이는 ${\pm}0.7%$ 미만이었다. 결 론: 듀얼에너지 영상의 획득은 싱글에너지에 비해 피폭선량을 감소시킬 수 있고, 가상 단색 영상은 CT number 보정에 유용하였다. 향상된 영상의 질은 인체의 기하구조 묘사와 전자 밀도 분포 형성에 도움이 될 것으로 사료된다. Purpose: To evaluate the image quality improvement and dosimetric effects on virtual monochromatic images of a Dual Source-Dual Energy CT(DS-DECT) for radiotherapy planning. Materials and Methods: Dual energy(80/Sn 140 kVp) and single energy(120 kVp) scans were obtained with dual source CT scanner. Virtual monochromatic images were reconstructed at 40-140 keV for the catphan phantom study. The solid water-equivalent phantom for dosimetry performs an analytical calculation, which is implemented in TPS, of a 10 MV, $10{\times}10cm^2$ photon beam incident into the solid phantom with the existence of stainless steel. The dose profiles along the central axis at depths were discussed. The dosimetric consequences in computed treatment plans were evaluated based on polychromatic images at 120 kVp. Results: The magnitude of differences was large at lower monochromatic energy levels. The measurements at over 70 keV shows stable HU for polystyrene, acrylic. For CT to ED conversion curve, the shape of the curve at 120 kVp was close to that at 80 keV. 105 keV virtual monochromatic images were more successful than other energies at reducing streak artifacts, which some residual artifacts remained in the corrected image. The dose-calculation variations in radiotherapy treatment planning do not exceed ${\pm}0.7%$. Conclusion: Radiation doses with dual energy CT imaging can be lower than those with single energy CT imaging. The virtual monochromatic images were useful for the revision of CT number, which can be improved for target coverage and electron densities distribution.

확률론적 파괴역학을 도입한 CANDU 압력관의 예리한 결함에 대한 건전성평가

이준성,곽상록,김영진,박윤원,Lee, Jun-Seong,Gwak, Sang-Rok,Kim, Yeong-Jin,Park, Yun-Won 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.4

This paper describes a probabilistic fracture mechanics(PFM) analysis based on Monte Carlo(MC) simulation. In the analysis of CANDU pressure tube, the depth and aspect ratio of an initial semi-elliptical surface crack, a fracture toughness value and delayed hydride cracking(DHC) velocity are assumed to be probabilistic variables. As an example, some failure probabilities of piping and CANDU pressure tube are calculated using MC method with the stratified sampling MC technique, taking analysis conditions of normal operations. In the stratified MC simulation, a sampling space of probabilistic variables is divided into a number of small cells. For the verification of analysis results, a comparison study of the PFM analysis using other commercial code is carried out and a good agreement was observed between those results.

건성안 환자에서 쇼그렌증후군의 빈도 및 임상양상

이준성,최원,이신석,윤경철.Jun Sung Lee. MD. Won Choi. MD. Shin Seok Lee. MD. Kyung Chul Yoon. MD. PhD 대한안과학회 2012 대한안과학회지 Vol.53 No.4

Purpose: To investigate the prevalence and clinical aspects of Sjögren syndrome in patients who were diagnosed with dry eye syndrome in Korea. Methods: The medical records of patients who were diagnosed with dry eye syndrome in a dry eye clinic during a 2-year period (March 2008 to March 2010) and were followed up for more than 3 months were reviewed retrospectively. Results: A total of 206 patients were included in the present study. Fifty-eight patients (28%) had Sjögren syndrome and 39 patients (19%) showed primary Sjögren syndrome. Sjögren syndrome patients showed poorer results than non-Sjögren syndrome patients in ocular surface disease index score (OSDI), tear break up time, Schirmer test score, and ocular surface staining score using the Oxford scheme (p < 0.05). Among the patients with primary Sjögren syndrome, 27 patients were SSA (anti-Ro antibodies) or SSB (anti-La antibodies) positive and 12 patients were sero-negative. There were no statistically significant differences in objective or subjective parameters between the sero-positive and sero-negative groups. Conclusions: Sjögren syndrome was observed in 28% of all dry eye patients, in two-thirds of severe dry eye patients. Sjögren syndrome patients showed more severe clinical aspects than dry eye patients with non-Sjögren syndrome. Diagnosing Sjögren syndrome through systemic evaluation is necessary in the patients with severe dry eye. J Korean Ophthalmol Soc 2012;53(4):499-504

국내 해양영토 정책의 현황과 과제

이준성,Lee, Junsung 한국해양전략연구소 2021 해양안보 Vol.3 No.1

이 논문은 국내 해양영토 정책을 분석한 것이다. 해양영토는 본래 국가영역(territory)에서 영해 하층토(subsoil)의 해저지형을 말한다. 정책적으로 해양영토는 영해와 배타적경제수역(EEZ), 대륙붕 등 우리나라 주권(sovereignty)이나 주권적 권리(sovereign rights)가 미치는 관할 해역을 넘어서 도서(島嶼)와 극지를 포함하는 광의적인 개념으로 해석된다. 또한, 국내 연구자 사이에서 해양영토는 독도 등의 도서 영토에서부터 이어도 등의 EEZ와 같은 해역(maritime zone)을 광범위하게 지칭하는 데 쓰이기도 한다. 이 연구의 목적은 이처럼 다양한 국내 해양영토의 개념을 검토하고, 정책의 형성과 변천을 살피는 것이다. 이러한 연구목적에 따라 이 연구의 구성은 다음과 같다. 2장에서는 해양영토 관련 기존의 논의를 검토하고, 이를 바탕으로 해양영토의 개념을 분석한다. 기존 학계에선 해양영토 개념에 관한 충분한 논의가 부족했고, 그 결과 해양영토라는 용어가 섬과 무분별하게 사용됐다. 이 장은 그러한 해양영토 개념을 심층 분석했다. 3장은 해양영토 정책의 형성 과정과 그 변천을 추적한다. 오늘날 국내 해양영토 개념은 공공영역에서 비로소 완성됐다고 볼 수 있다. 이를 설명하기 위해 국내 해양영토 정책의 사령탑인 해양수산부의 활동을 정리한다. 4장에선 해양영토 개념과 유사성을 보이는 중국의 남색 국토(藍色國土)와의 비교를 통해 그 개념을 분석한다. 중국의 남색국토 개념은 오늘날 중국의 해양활동을 위한 정책적 토대로서 해양영토와 여러 유사점이 있으므로, 이 두 가지를 비교하는 것이 유의미하다고 판단했다. 이를 통해 마지막 5장에서 해양영토 정책추진을 위한 제언을 도출한다. This article analyzed maritime territorial policies in Korea. Marine territory originally refers to the topography of the subsoil in a country's territorial sea. From a political perspective, it is a broad concept that includes islands and polar regions beyond the jurisdiction of Korean sovereignty or sovereign rights, such as territorial waters, EEZs, and continental shelves. Also, Korean researchers use "maritime territory" as a term for maritime zones that stretch from Ieodo (Korean EEZ) to Dokdo Island. The purpose of this study is to review the concepts of various domestic maritime territories and examine the formation and change of policies. The article is structured as follows. Chapter 2 reviews past discussions on maritime territories and analyzes the concept of maritime territory based on them. The term "maritime territory" is used indiscriminately with islands due to the lack of discussion on this matter between academic circles in the past. Therefore, this chapter provides an in-depth analysis of the concept of maritime territory. Chapter 3 tracks the formation and change of maritime territorial policies. Today, the concept of domestic maritime territory has been completed in the public domain. The activities of the Ministry of Oceans and Fisheries, the control tower of domestic maritime territorial policies, are summarized to explain this concept. Chapter 4 analyzes the concept of maritime territory by comparing it with China's blue state territory (藍色國土). As China's concept of blue state territory has many similarities with maritime territory as a political base for China's maritime activities today, comparing these two concepts would be significant. Based on the above, Chapter 5 derives suggestions to promote maritime territorial policies.

화학적 기상 반응에 의한 탄화규소 피복 흑연의 시뮬레이션(Ⅰ)

이준성,최성철,Lee, Joon-Sung,Choi, Sung-Churl 한국세라믹학회 2001 한국세라믹학회지 Vol.38 No.9

2차원적 몬테 칼로 시뮬레이션을 사용하여, 화학적 기상 반응법에 의한 탄화규소 전환층의 생성에 미치는 온도의 영향을 조사하였다. 화학적 기상 반응법은 실리카의 열탄화 환원법에 근거하며, 흑연 기판의 탄소와 실리카 반응기체와의 화학적 반응에 의하여 탄화규소 전환층을 형성하는 방법이다. 탄화규소는 반응기체의 확산 및 반응과 같은 열적활성화 과정을 통하여 생성되기 때문에 탄화규소 전환층의 형성은 온도에 크게 의존함을 알 수 있다. 본 연구에서는 몬테 칼로법을 사용하여 삼각격자로 배열된 2차원적인 계에서 흑연 기판의 미세 기공을 따라 확산된 반응기체와 탄소와의 반응에 의해서 탄화규소가 형성되는 과정을 시뮬레이션을 행하였다. 반응 온도를 1900K, 2000K, 2100K, 2200K로 조건을 달리하여 시뮬레이션 하였으며, 그 계산 결과를 실험 결과와 비교하여 재현성을 검토하고 탄화규소 전환층의 두께와 화학적 조성 구배에 대한 반응 온도의 영향을 검증하기 위한 것이다. A two-dimensional Monte Carlo simulation has been used to investigate the effect of the reaction temperature on the formation of the silicon carbide conversion layer near the surface of graphite substrate The carbothermal reduction of silica is the reaction mechanism of silicon carbide formation on graphite substrate by chemical vapor reaction methods. The chemical composition of silicon carbide conversion layer gradually changes from carbon to silicon carbide because gaseous reactants diffuse through micropores within graphite substrate and react with carbon at the surface of inner pores. The simulation was carried out under the condition of reaction temperature at 1900K, 2000K, 2100K and 2200K for 500MCS. It was found from the results of simulation that the thickness of silicon carbide conversion layer increases with reaction temperature.

결정질 실리콘 태양전지용 실리콘 기판의 표면 미세구조에 따른 곡강도 특성

이준성,권순우,박하영,김영도,김형준,임희진,윤세왕,김동환,Lee, Joon-Sung,Kwon, Soon-Woo,Park, Ha-Young,Kim, Young-Do,Kim, Hyeong-Jun,Lim, Hee-Jin,Yoon, Se-Wang,Kim, Dong-Hwan 한국재료학회 2009 한국재료학회지 Vol.19 No.1

The influence of various surface morphologies on the mechanical strength of silicon substrates was investigated in this study. The yield for the solar cell industry is mainly related to the fracturing of silicon wafers during the manufacturing process. The flexural strengths of silicon substrates were influenced by the density of the pyramids as well as by the size and the rounded surface of the pyramids. To characterize and optimize the relevant texturing process in terms of mechanical stability and the fabrication yield, the mechanical properties of textured silicon substrates were investigated to optimize the size and morphology of random pyramids. Several types of silicon substrates were studied, including the planar type, a textured surface with large and small pyramids, and a textured surface with rounded pyramids. The surface morphology and a cross-section of the as-textured and fractured silicon substrates were investigated by scanning electron microscopy.

消風散加味의 抗알레르기 效果에 關한 實驗的 硏究

이준성,서형식,노석선,Lee, Jun-Seong,Seo, Hyung-Sik,Roh, Seok-Seon 대한한방안이비인후피부과학회 2001 한방안이비인후피부과학회지 Vol.14 No.2

This study was carried out to prove the anti-allergic effect of SPS-GM, which is gained by controlled Cytokines making all the difference to Th2 cell development. The results were obtained as follows : 1. From the SPS-GM treatment about BMC cell, in case of the IL-4, an important factor of the Th2 cell development, SPS-GM didn't show considerable effect. 2. The INF-${\gammer}$, mutual Cytokines of IL-4, was increased more than twice. 3. Histamine from the Master cell and Nitric oxide from indisposition response were a little decreased. According to the above results, it is suggested that SPS-GM has anti-allergic effect.

미세각막절개도를 이용한 데스메막박리 각막내피층판이식술의 국내 장기 임상 결과

이준성,박영걸,윤경철,Jun Sung Lee,Yeoung Geol Park,Kyung Chul Yoon 대한안과학회 2010 대한안과학회지 Vol.51 No.11

Purpose: To evaluate the long-term results of Descemet’s stripping automated endothelial keratoplasty in Korea (DSAEK). Methods: Seven patients with bullous keratopathy who underwent DSAEK and who were followed-up for more than 18 months were reviewed retrospectively. Best corrected visual acuity, refraction, corneal thickness, and endothelial cell count were examined before and after surgery. Results: The mean follow-up period was 19.9 ± 2.9 months (18 to 24 months), and the mean age was 61.42 ± 10.13 years (46 to 76 years). Six patients (85.7%) showed successful results after surgery. Best corrected visual acuity (logMAR) was significantly improved from 1.62 (median) to 1.15 (median) (p = 0.027) at one month after surgery and was maintained until the final follow-up period. There were no statistical differences in spherical ametropia or astigmatism before or 18 months after the operation. Graft failure was observed in one case, in which penetrating keratoplasty was performed 12 months after DSAEK. Conclusions: Long term results of DSAEK showed fast visual recovery, low ametropia and astigmatism. DSAEK may be a good option for the surgical management of corneal endothelial disease. J Korean Ophthalmol Soc 2010;51(11):1431-1437

數種의 天然物을 이용한 瘙痒症治療에 대한 實驗的 硏究

이준성,서형식,노석선,Lee, Jun-Seong,Seo, Hyeong-Sik,No, Seok-Seon 대한한방안이비인후피부과학회 2001 한방안이비인후피부과학회지 Vol.14 No.1