Light-extraction efficiency control in AlGaN-based deep-ultraviolet flip-chip light-emitting diodes: a comparison to InGaN-based visible flip-chip light-emitting diodes.

Lee, Keon Hwa,Park, Hyun Jung,Kim, Seung Hwan,Asadirad, Mojtaba,Moon, Yong-Tae,Kwak, Joon Seop,Ryou, Jae-Hyun Optical Society of America 2015 Optics express Vol.23 No.16

<P>We study light-extraction efficiency (LEE) of AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) using flip-chip (FC) devices with varied thickness in remaining sapphire substrate by experimental output power measurement and computational methods using 3-dimensional finite-difference time-domain (3D-FDTD) and Monte Carlo ray-tracing simulations. Light-output power of DUV-FCLEDs compared at a current of 20 mA increases with thicker sapphire, showing higher LEE for an LED with 250-관m-thick sapphire by ~39% than that with 100-관m-thick sapphire. In contrast, LEEs of visible FCLEDs show only marginal improvement with increasing sapphire thickness, that is, ~6% improvement for an LED with 250-관m-thick sapphire. 3D-FDTD simulation reveals a mechanism of enhanced light extraction with various sidewall roughness and thickness in sapphire substrates. Ray tracing simulation examines the light propagation behavior of DUV-FCLED structures. The enhanced output power and higher LEE strongly depends on the sidewall roughness of the sapphire substrate rather than thickness itself. The thickness starts playing a role only when the sapphire sidewalls become rough. The roughened surface of sapphire sidewall during chip-separation process is critical for TM-polarized photons from AlGaN quantum wells to escape in lateral directions before they are absorbed by p-GaN and Au-metal. Furthermore, the ray tracing results show a reasonably good agreement with the experimental result of the LEE.</P>

An Investigation on the Life of Master Won Guk Lee, the Creator of Chung-Do-Kwan

( Seon Young Jung ),( Jun Ho Lee ),( Seung Woo Shin ),( Chun Hwan Cho ),( Seung Hyun Jang ),( Won Shin ) 경남대학교 기초과학연구소 2014 기초과학지 Vol.31 No.-

The purpose of this study is to review (or, investigate) the life of Won Guk Lee. He is the creator of Chung-Do-Kwan, which is one of the five original Taekwondo kwans. Data was gathered from advanced research, newspapers, documentaries, the Internet, magazines, and journals etc. Thus, we were able to create a sequence of events based on the research data. First, we can say that in Won Guk Lee``s career, he created Chung-Do-Kwan and brought Dangsoodo to Korea. These events have had a significant development on Taekwondo. Second, Taekwondo curriculum, which was published by Won Guk Lee, established the foundation of Taekwondo poomsae, as well as giving us the pure spirit of Korean martial arts.

Personal Computer를 이용한 반주문형 집적 회로 설계용 Workstation

이문기,이석호,김승환 연세대학교 산업기술연구소 1987 논문집 Vol.19 No.2

LEDISO는 레이아웃을 설계하기 위한 소프트웨어이며, 하드웨어 구성에 따르는 LEDISO의 하드웨어 의존성을 줄이기 위하여 그래픽 소프트웨어 표준인 GKS의 환경조건을 이용하였다. LEDISO의 데이타 구조는 CIF 데이타 구조를 기본으로 Polygon, Box, RFlash, Wire, Label 등을 오브젝트(object)로 가지며, Master를 이용한 SFF로 화일 관리를 한다. GKS의 세그먼트(Segment)를 이용한 아이컨(Icon)을 메뉴에 도입하여 시각적으로 사용자 인터페이스에 도움이 되도록 하였다. LEDISO, Layout EDiting SOftware for IC design, is implemented in C language with the environment condition of GKS which is the graphic standard software in order to reduce the hardware dependency. The data structure of LEDISO with the base of CIF data structure has the object as polygon, box, rflash, wire and label, managing files as SFF using the Master. In order to help user, the menu consisted of string and icon which has the segment of GKS is adopted in LEDISO.

Topiramate의 기분안정 효과 및 체중감소 효과 : 사용 1례 A case report

이승환,정영조 인제대학교 백병원 2002 仁濟醫學 Vol.23 No.3

Topiramate is a novel antlepileptic agent with a wide spectrum mechanism of action, and recent reports indicate that it may have mood stabilizing properties in bipolar disorder. We experienced topiramate treatment of a 38 years old woman with bipolar disorder who had 5 previous hospitalizations for mood unstability during past 4 years. For the past 4 years, she had been treated with lithium, carbamazepine and valproate as well as small dosages of antipsychotics. But her treatment responses were not good enough because of weight gain and incomplete mood stabilizing effects of previous medications. We used topiramate for the recent new manic episode. During 8 weeks of trial, topiramate was well tolerated. and her mood was better stabilized than ever. The patients, now on 1000㎎/4ay of topiramate is mostly asymptomatic, and her weight was reduced from 68㎏ to 62㎏, and has functioned well for over 3 months.

공간 데이터에 대한 최근접 질의 처리에 관한 연구

이석균,류승환 단국대학교 1999 論文集 Vol.34 No.-

In spatial database systems, various kinds of queries exist. A frequent type of queries in spatial database systems is the query to find nearest neighbors. Many studies have been performed on processing such queries, and one representative work, which uses index structure of R-tree family, is 「Nearest Neighbor Queries」 by Roussopoulos. However, the algorithm proposed by Roussopoulos has suffered perfomance decrease during searching, since his algorithm does not utilize all the information on the nodes already visited. In this paper, in order to resolve this problem, we present an improved algorithm to find nearest neighbors using a global priority queue. Finally, by experimenting these algorithms on various test data, we show that the performance of our improved algorithm is superior to the Roussopoulos's algorithm.

여러 개의 패치로 이루어진 곡면에서 재매개변수화를 통한 공구경로 생성

이성근,권성환,양승환 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.5

Recently, according to the various taste of consumers, the design of a product is changed variously and complicatedly. The complicated product is not usually constructed with one patch but multi-patch. By the way, in machining, higher pre-cision and the reduction of leading and machining time is required. But, for the multi-patch sculptured surface, the amount of machining data becomes large. This means the increase of leading and machining time. In this study, the tool path generation method with reparameterization is proposed for multi-patch sculptured surface and variable step size using NURBS is used to satisfy the precision and to reduce leading and machining time.

악교정 수술 후 발생하는 신경회복에 대한 연구Ⅰ

이동근,조이수,민승기,오승환,정창주,이은택 대한악안면성형재건외과학회 2001 Maxillofacial Plastic Reconstructive Surgery Vol.23 No.2

Dysfunction of the inferior alveolar nerve indicated by various degree of numbness of the lower lip and chin is one of the few drawbacks of mandibular osteotomy, especially Bilateral Sagittal Split Ramus Osteotomy(BSSRO) and genioplasty. Although it has been recorded throughout the history of this techniques, it is true etiology poorly understood. In this study, 22 consecutive patients under class III malocclusiion impression and undergoing orthognathic surgery(BSSRO only 11 case, BSSRO with genioplasty 11 case) were studied using 4 neurosensory test(static light touch, directional discrimination, two-point discrimination, pin pressure nociception) with post OP 1 week, 2 weeks,4 weeks, 8 weeks, 12 weeks, 24 weeks, On control group, 10 members without trauma and nerve damage history, nerve test was accomplished. We concluded majority of patients return of sensation during post operative 24 weeks. Althought immediate nerve deficit are 92.2%, 97.2% 88.9% these are recovered to 25%, 35.72%, 10.71% at 24 weeks. Nerve recovery rate increased prominently between post 4 weeks and 8 weeks. There is no statistically difference about neurosensory deficit among the chin area. Neurosensory deficit more severe when the BSSRO with genioplasty group than the only BSSRO group. Immediate neurosensory deficit is larger left side than right side but after 6 months, there is no significantly difference between left side and right side. Static light touch and pin pressure nociception are more sensitive method of neurosensory deficit than two point discrimination.

상악 제3대구치 발거후 발생한 광범위한 피하기종

이은택,민승기,오승환,이동근 大韓顎顔面成形再建外科學會 2003 Maxillofacial Plastic Reconstructive Surgery Vol.25 No.1

Subcutaneous air emphysema is a relatively uncommon phenomenon. It has been reported in both the medical and dental literature following such various procedures as rectal biopsy, nasogastric intubation, radical neck dissection, tonsillectomy, adenoidectomy, root canal treatment, dental restoration and extraction of maxillary and mandibular teeth. The most common cause involves extraction of mandibular third molar. Subcutaneous emphysema of the head, neck and thorax is a swelling caused by introduction of air into the space of the connective tissue. The clinical signs are local swelling, tenting of the skin, and crepitation on palpation. In extreme casesk, air has been reported to pass through the masticatory space into the parapharyngeal and retropharyngeal space, and penetrate into the mediastinum. If the inflowing air contains bacteria, serious infection may ensue. The first case of subcutaneous emphysema associated with a dental procedure was first reported in 1900. This emphysema is a often limited only to the spaces of head and neck, but also can involve deeper structure. This case is diffuse subcutaneous emphysema following maxillary third molar extraction with a high-speed drill.

위장관을 침범한 Henoch-Sch o¨nlein purpura 1예

이승곤,김채규,서종옥,이호영,이호준,정회상,박유환,정춘해 朝鮮大學校 附設 醫學硏究所 1996 The Medical Journal of Chosun University Vol.21 No.2

Henoch-Scho¨nlein purpura(H-S purpura) is a systemic necrotizing vasculitis of small vessels that is characterized by nonthrombocytopenic palpable purpura on the buttocks and extremities, arthritis of knees and ankles, glomerulonephritis, and colicky abdominal pain, histologically characterized by leukocytoclastic vasculitis. Gastrointestinal involvement with colicky abdominal pain and GI bleeding, most frequently in jejunum and ileum, occurs in above a half of all patients, but common in children. We performed GI endoscopy in a case of H-S Purpura. Gastroduodenoscopic findings showed erythemas and erosions in gastric antrum, and mucosal edema and petechiae in duodenal 2nd portion. Colonoscopic findings showed 5-10㎜ sized multiple shallow hemorrhagic ulcers in transverse and descending colons We report a case of H-S purpura involving colon with literatural review.

과학 영재 학생들의 사고양식에 따른 지구시스템에 대한 인지 특성

이효녕,김승환 경북대학교 과학교육연구소 2009 科學敎育硏究誌 Vol.33 No.1

이 연구의 목적은 과학 영재 학생들의 사고 양식에 따른 지구시스템에 대한 인지 특성을 분석하는 것이다. 연구 대상은 광역시 소재 대학 부설 과학영재교육원에 재학 중인 24명이다. 연구 방법은 먼저 과학 영재 학생들을 대상으로 Sternberg의 정신자치제 이론에 근거로 사고양식 측정 검사를 실시한 후, 그 유형에 따라 Type Ⅰ (입법적, 사법적, 전체적, 진보적)과 Type Ⅱ (행정적, 지엽적, 보수적)집단으로 구분하였다. 그 후 각 집단에 대해 설문지 3종(A, B, C형), 단어 연상, 그림 분석, 개념 지도, 숨겨진 차원파악하기(hidden dimension inventory), 자료해석 및 그 결과에 대한 심층 면담을 실시하였다. 과학 영재 학생들의 사고양식 유형은 입법적, 사법적, 무정부적, 전체적, 외부적, 그리고 진보적 사고 양식의 특성을 나타내어 새로운 과제를 선호하며, 창의적인 방식으로 문제를 해결하려는 경향을 보여주었다. 사고 유형에 따른 지구시스템에 대한 인지 특성에 대한 연구 결과는 다음과 같다. 첫째, ‘시스템 이해’에서 Type Ⅰ, Ⅱ 집단의 양적 측정치는 비슷하였으나, 세부적으로 살펴보면 상당한 차이가 존재한다. 둘째, ‘시스템 내 관계 파악’은 사고양식 유형과 상당히 밀접한 관계를 가지고 있으며, Type Ⅰ집단이 보다 다각적, 역동적, 순환적으로 접근하여 보다 유리하다. 셋째, ‘시스템 일반화’에서 시스템에 대한단순 해석 능력은 두 집단 모두 비슷하나, 숨겨진 차원 요소를 가미하여 추정할 경우 일반화 경향이 Type Ⅰ집단이 우수하다. 하지만 시스템 예측 측면에서는 집단에 관계없이 미약하다. 이러한 결과를 볼 때 시스템 학습 프로그램 개발과 적용에 있어 다양한 대상에 대한 구체적인 개발 전략이 요구되며, 이를 통한 시스템 인지와 관련된 여러 분야에서의 활용성과 기대 효과가 클 것이라 생각된다. The purpose of this study was to analyze recognition characteristics of science gifted students on the earth system based on their thinking style. The subjects were 24 science gifted students at the Science Institute for Gifted Students of a university located in metropolitan city in Korea. The students’ thinking styles were firstly examined on the basis of the Sternberg’s theory of mental self-government. And then, the students were divided into two groups: Type Ⅰ group(legislative, judicial, global, liberal) and Type Ⅱ group(executive, local, conservative) based on Sternberg’s theory. Data was collected from three different type of questionnaires(A, B, C types), interview, word association method, drawing analyses, concept map, hidden dimension inventory, and in-depth interviews. The findings of analysis indicated that their thinking styles were characterized by ‘Legislative’, ‘Executive’, ‘Anarchic’, ‘Global’, ‘External’, ‘Liberal’ styles. Their preference were conducting new projects and using creative problem solving processes. The results of students’ recognition characteristics on earth system were as follows: First, though the two groups’ quantitative value on ‘System Understanding’ was very similar, there were considerable distinctions in details. Second, ‘Understanding the Relationship m the System’ was closely connected to thinking styles. Type Ⅰ group was more advantageous with multiple, dynamic, and recursive approach. Third, in the relation to ‘System Generalization’ both of the groups had similar simple interpretational ability of the system, but Type Ⅰ group was better on generalization when ‘hidden dimension inventory’ factor was added. On the system prediction factor, however, students’ ability was weak regardless of the type. Consequently, more specific development strategies on various objects are needed for the development and application of the system learning program. Furthermore, it is expected that this study could be practically and effectively used on various fields related to system recognition.