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>

Who Becomes Exposed to Celebrity Activism on Twitter?

Seulgi Jang,Yujin Kim,Byung Joon Lee,Kyu S. Hahn 한국언론학회 2015 Asian Communication Research Vol.12 No.1

Twitter has significantly amplified celebrity presence on civic affairs. Although celebrities hold little expertise on policy affairs, they can be quite influential since their popularity allows them to reach large audiences. There is an ongoing debate concerning the democratic implications of increasing celebrity influence in policy affairs. In the current study, taking Oisoo Lee as a test case, we investigate the political implications of celebrity following on Twitter. We first compare Lee’s followers with those of ten news outlets, based on the co-following pattern among 1,442,317 Twitter users. We also had access to supplementary survey data on 11,725 members of an online survey panel who had provided their Twitter screen names. For these survey participants, we are able to match their following behavior with individual level attributes. Our results reveal that Lee’s followers are not ideologically skewed in either direction. Indeed, our survey findings confirmed that a vast majority of Lee’s followers identified themselves as independent. On the other hand, survey results show that Oisoo Lee is more likely to attract those lacking the ability to process one-sided information in a balanced manner. This raises a concern that they could be easily misinformed or misled.

휴대폰 카메라용 자동초점 구동기의 충격해석

이성민,김봉석,송준호,이수훈,이혜진,이문구,송준엽,이창우 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

Recently, the robustness against daily impact is important according to portablization and downsizing of mobile electronics. Especially, almost parts of cellular phone should undergo drop test when they fall 1.5 m above ground. This test simulates the case when cellular phone slips through user's fingers while he is talking on the phone. This paper studies a drop test of auto focusing (AF) actuator for camera module in cellular phone. This component is composed of voice coil motor (VCM) as an actuator and leaf spring as a guide and suspension. The leaf spring's deformation is essential for the test because its permanent distortion disables the focusing, and then, a high quality photograph cannot be obtained. Up to now the drop test has been carried out after fabricating real AF actuator. We propose a dropt test model which simulates the drop test based on finite element analysis. This model makes us enable investigate the stress acting on the clamping and curved parts of leaf spring. Stress over Von Mises criterion lets the spring deformed permanently, and then AF actuator malfunctioned, It helps us to design and modify AF actuator without manufacturing the real product. And also, it saves the time and cost for the development of new products.

[NEWS] 신진연구자 소개_이준호 Joon-Ho Lee

이준호(Joon-Ho Lee) 대한화학회 2023 화학세계 Vol.63 No.5

Miscanthus sinensis 와 타 식물과의 친근성에 관한 연구

정일구(Il Koo Lee),이호준(Ho Joon Lee),이경순(Kyung Soon Lee) 한국식물학회 1970 Journal of Plant Biology Vol.13 No.4

Althought allelopathy has been cleary established for Pinus densiflora by Lee-Monsi, the auther suspected that Miscanthus sinensis which grows vigrously in such Korean pine forests might also exhibit the phenomenon. A total of 33 species having an affinity in the Miscanthus group were recorded in the field. Out of these, five species; Patrinia scabiosaefolia, Lespedeza crytobotrya. Oenothera odorata, Raphanus sativus var. acanthiformis, and Zoysia japonica were considered the A group. Five other species which have no affinity to Miscanthus sinensis, Amaranthus patulus, Solanum nigrum, Capsella bursa-pastorris var. triangularis, Chemopodium album var. centrorubrum and Alopeculus amurensis were considered the B group. Extracts of Miscanthus sinensis were applied to determine relative germination and growth. It was found the growth in the B group was promoted by a cold water extract of Miscanthus stems and leaves, but inhibited remarkably by an extract obtained by passing cold water through Miscanthus root. As expected, growth in the A group was promoted by both experimental treatments.

서울의 Penicillinase Producing Neisseria gonorrhoeae 발생빈도(1998)

김재홍,김준호,반재용,이정우,황성주,정준규,정성태,강진문,조흔정,홍창의,정혜신,이한승,김이선,이봉길,이종호,선영우,한기덕,윤성필,이성훈,안종성,박석범,문승현,조항래,김형섭,류지호,황재영,박준홍,손상욱 한양대학교 의과대학 2001 한양의대 학술지 Vol.21 No.1

In recent years, gonorrhea has been pandemic and remains one of the most common STDs in the world, especially in developing countries. For the detection of a more effective therapeutic regimen and assessing the prevalence of Penicillinase Producing Neisseria gonorrhoeae(PPNG), we have been trying to study the patients who have visited the Venereal Disease Clinic of Choong-Ku Public Health Center in Seoul since 1980 by menas of the chromogenic cephalosporin method. In 1998, 93 strians of N. genorrhoeae were isolated, among which 60(64.5%) were PPNG. The prevalence of PPNG in Seoul, which had been decreased to 39% in 1996 after a peak of 74.3% in 1993, is increased to 64.5% in 1998.

골형성부전증 10예의 임상적 특징

이형숙,김현주,조재현,이승원,김현아,최준혁,송영준,김대중,이관우,정윤석 대한내분비학회 2003 Endocrinology and metabolism Vol.18 No.5

연구배경 및 방법: 골형성부전증은 비교적 희귀한 유전병으로 교원질 대사 장애로 인한 골의 취약성과 다발성 골절 및 척추측만증 등을 특징으로 한다. 유전방식과 표현형의 발현 정도에 따라 다양한 임상 양상을 보이며, 임상적 중증도에 따라 4가지 형태로 분류된다. 지금까지 국내 보고는 분만과정이나 태아 진찰시 골격이상으로 발견된 증례보고가 주였다. 저자들은 비교적 경미한 임상 양상을 보이는 예를 포함한 다수의 골형성부전증 환자들의 전반적인 임상적 특징에 대해 보고하는 바이다. 결과: 2001년 6월부터 2003년 2월까지 골형성부전증으로 진단받은 6 가계, 10예를 대상으로 하였다. 평균 나이는 27.3(5∼56)세였고 소아가 2예였다. 모두 상염색체 우성으로 유전되었으며, 제 I형이 4예, 제 III형이 4예, 그리고 제 IV형이 2예였다. 전 예에서 다수의 골절 경험이 있었고, 골밀도 저하와 골피질 두께 감소 소견이 관찰되었다. 전신의 평균 골밀도는 0.690(0.421∼1.039) g/cm²였다. 골형성지표로 측정된 sAlk는 소아의 경우만 증가되어 있었고, 골흡수지표로 측정된 uDPD의 평균치는 12.9(4.4∼36.3) nM/mM Cr으로 증가된 소견을 보였다. mobility score는 대부분 3,4단계에 속해 있었다. 중증형일수록 진단 시의 mobility score가 낮은 경향을 보였다. 결론: 한국인 골형성부전증 환자의 임상적 특징을 살펴본 결과 기존의 보고된 II형 외에도 I, III, IV형이 다양하게 존재함을 알 수 있었으며, 모든 예에서 상염색체 우성으로 유전됨을 확인할 수 있었다. 또한 모든 예에서 증가된 골흡수로 인한 골밀도 저하와 골절을 확인할 수 있었다. Osteogenesis Imperfecta (OI) is a relatively rare hereditary disease, which is characterized by multiple bone fractures and spine scoliosis, due to the fragility of bone, and is often associated with blue sclerae, deafness and dentinogenesis imperfecta. Four types of OI can be distinguished, according to the clinical findings. Although mutations affecting type I collagen are responsible for the disease in most patients, the mechanism by which the genetic defects cause abnormal bone development remains to be fully understood. Here, the clinical characteristics of 10 OI patient cases are reported, with a review of the literature. All the cases, including 4 type I, 4 type III and 2 type IV, inherited OI as an autosomal dominant trait. All the subjects had multiple old fractures and decreased bone densities. In this study, the biochemical marker of bone formation, serum alkaline phosphatase, was found to be increased only in the pediatric OI patients, while the biochemical marker of bone resorption, urinary deoxypyridinoline, was increased in all cases. The mobility score was found to correlate with the severity of the type on diagnosis (J Kor Soc Endocrinol 18:496∼503, 2003).

Development of a Monitoring System for Water-borne Bacteria by a Molecular Technique, PCR-RELP-sequence Analysis

이혜영,--,--,--,--,--,-- THE KOREAN SOCIETY FOR BIOMEDICAL LABORATORY SCIEN 2003 Journal of biomedical laboratory sciences Vol.9 No.3

Since water borne infection causes acute diseases and results in spread of diseases by secondary infection, the prevention is very important. Therefore, it is necessary to have a method that is rapid and effective to monitor pathogenic bacteria in drinking water. In this study, we employed a systematic method, Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) analysis, to develop an effective monitoring system for possible bacterial contaminants in drinking water. For this purpose, PCR primers were derived from 992 bp region of the 16s rRNA gene that is highly conserved through the different species of prokaryotes. To test whether the PCR primers designed are indeed useful for detecting all the possible microbial contaminants in the water, the primers were used to amplify 16s rRNA regions of different microbial water-borne pathogens such as E. coli, Salmonella, Yersinia, Listeria, and Staphylococcus. As expected, all of tested microorganisms amplified expected size of PCR products indicating designed PCR primers for 16s rRNA indeed can be useful to amplify all different microbial water-borne pathogens in the water. Furthermore, to test whether these 16s rRNA based PCR primers can detect bacterial populations present in the water, water samples taken from diverse sources, such as river, tap, and sewage, were used for amplification. PCR products were for then subjected for cloning into a T-vector to generate a library containing 16s rRNA sequences from various bacteria. With cloned PCR products, RFLP analysis was done using PCR products digested with restriction enzyme such as Hae Ⅲ to obtain species-specific RFLP profiles. After PCR-RFLP, the bacterial clones which showed the same RFLP profiles were regarded as the same ones, and the clones which showed distinctive RFLP profiles were subsequently subjected for sequence analysis for species identification. By this PCR-RFLP analysis, we were able to reveal diverse populations of bacteria living in water. In brief, in unsterilized natural river water, over 60 different species of bacteria were found. On the other hand, no PCR products were detected in drinking tap-water. The results from this study clearly indicate that the PCR-RFLP-sequence analysis can be a useful method for monitoring diverse, perhaps pathogenic bacteria contaminated in water in a rapid fashion.

다중 질의 결합을 통한 검색 효과의 개선

이기호,이준호,이규철 한국문헌정보학회 1997 한국문헌정보학회지 Vol.31 No.1

일반적으로 주어진 정보 요구에 대하여 서로 다른 사용자는 서로 다른 질의를 생성할 수 있으며, 또는 한명의 사용자가 통제어의 사용 여부에 따라 서로 다른 질의를 생성할 수 있다. 최근 정보 검색 분야의 연구들은 이러한 서로 다른 질의 표현의 서로 다른 문서 집합을 검색함을 보여준다. 본 논문에서는 하나의 사용자 질의에 대하여 다양한 적합성 피드백 방법을 적용함으로써 다중의 질의들을 자동으로 생성한 후, 생성된 다중 질의들을 다시 하나의 질의로 결합하는 방법을 제안한다. 또한 실험을 통하여 자동으로 생성된 다중의 질의들을 결합함으로써 보다 높은 검색 효과를 얻을 수 있음을 입증한다 Different users or the same user using controlled versus free-text vocabularies could generate different queries for the same information need. It has been known in the information retrieval literature that different query representations may retrieve different sets of documents. In this paper, we first generate multiple query vectors from a given information problem by using different relevance feedback methods. Then we combine the multiple query vectors into a single query vector. We also show through experiments that significant improvements can be achieved by the combination of the multiple query vectors

가토 간의 VX2 carcinoma : 종양이식방법에 따른 영상소견의 차이 Different Radiologic Features According to Innoculation Methods

이준우,정진욱,최국명,김종재,김세형,최준일,이경호,김승협,박재형 대한초음파의학회 2000 ULTRASONOGRAPHY Vol.19 No.3