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>

Improvement of Desulfurization Efficiency via Numerical Simulation Analysis of Transport Phenomena of Kanbara Reactor Process

Yong‑Joon Lee,Kyung‑Woo Yi 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4

The Kanbara reactor (KR) process is a mechanical stirring method that reacts hot metal with desulfurization flux; it is a widelyimplemented desulfurization method in contemporary steel production. This study aimed to develop a new impeller profilefor improving the desulfurization efficiency of the KR process. We implemented operational data analysis, a computationalfluid dynamics simulation based on the operational data and performed testing and analysis with impeller models on-site aproduction facility. Operational data from the production facility was gathered over a 3-year period. Seven impeller modelswith varying impeller blade width (top and bottom), height, inclination, and curvature (curved, straight, and combination)were simulated. The results were analyzed to determine the optimal conditions. A new impeller design was selected for onsiteoperational testing to investigate the in situ desulfurization efficiency over 350 charges, and the results corroborated thepredictions by the numerical simulations. It is expected that the proposed process modification can be successfully used forimproving industrial desulfurization efficiency.

정신분열병에 대한 리스페리돈의 효과 및 안정성

이민수,김용구,김영훈,연병길,오병훈,윤도준,윤진상,이철,정희연,강병조,김광수,김동언,김명정,김상훈,김희철,나철,노승호,민경준,박기창,박두병,백기청,백인호,손봉기,손진욱,양병환,양창국,우행원,이정호,이종범,이홍식,임기영,전태연,정영조,정영철,정인과,정인원,지익성,채정호,한상익,한선호,한진희,서광윤 大韓神經精神醫學會 1998 신경정신의학 Vol.37 No.1

연구목적 : 본 시험의 목적은 임상시험 시작전에 연구자들을 대상으로 PANSS Workshop을 통하여 PANSS, ESRS에 대한 국내에서의 표준화 작업을 구축하고 새로운 정신병 치료제인 리스페리돈의 효과와 안정성을 재확인하여 리스페리돈 사용에 대한 적정화를 이루는데 있다. 연구방법 : 1996년 4월부터 1996년 9월까지 국내 39개 대학병원 정신과에 입원중인 혹은 증상이 악화되어 입원하는 정신분열병 환자 377명을 대상으로 다시설 개방 연구를 시행하였다. 1주일간의 약물 배설기간을 가진후, 리스페리돈을 8주간 투여하였고, 기준점, 1주, 2주, 4주, 그리고 8주후에 평가되었다. 용량은 제1일에는 리스페리돈 1mg씩 1일 2회, 제2일에는 2mg씩 1일 2회, 제3∼7일에는 3mg씩 1일 2회 투여하였다. 이후 환자의 임상상태에 따라 임의로 증량할 수 있으며, 최대 일일 16mg을 초과하지 않도록 하였다. 추체외로 증상을 조절하기 위한 투약을 허용하였다. 임상증상 및 부작용의 평가는 PANSS(Positive and Negative Syndrome Scale), CGI(Clinical Global Impression) 그리고 ESRS(Extrapyramidal Symptom Rating Scale)을 사용하였다. 연구결과 : 377명중 343명(91%)이 8주간의 연구를 완결하였다. 치료 종결시점인 8주후 PANSS 총점수가 20% 이상 호전된 경우를 약물 반응군으로 정의할때, 약물반응군은 81.3%였다. 리스페리돈에 반응하는 예측인자로는 발병연령, 이전의 입원 횟수, 유병기간이 관련 있었다. 리스페리돈은 1주후부터 PANSS양성, 음성, 및 일반정신병리 점수상에 유의한 호전을 보여 효과가 빨랐다. CGI의 경우도 기준점에 비해 1주후부터 유의한 감소를 나타내었다. ESRS의 경우, 파킨슨 평가점수는 기준점과 비교해 투여 1주, 2주, 4주후 유의하게 증가되었다가 8주후 기준점과 차이가 없었다. Dystonia 평가점수는 1주후만 유의한 증가를 보였으며, dyskinesia 평가점수는 유의한 차이가 없었다. 혈압, 맥박수의 생명징후 및 일반 혈액학 검사, 생화학적 검사, 심전도 검사에서 유의한 변화는 없었다. 결 론 : 이상의 다시설 개방 임상 연구를 통해 리스페리돈은 정신분열병 환자에서 양성증상뿐만 아니라 음성증상 및 전반적인 증상에도 효과적인 것으로 사료된다. 보다 명확한 평가를 위해서는 다른 항정신병약물과의 이중맹검 연구가 필요할 것으로 생각되며, 또한 장기적 치료에 대한 평가도 함께 이루어져야 하겠다. Objective : The purpose of this study was to investigate the efficacy and safety of risperidone in the treatment of Korean schizophrenic patients. Method : This multicenter open study included 377 schizophrenic patients drawn from 39 university hospitals. After a wash-out period of 1 week, the schizophrenic patients were treated with risperidone for 8 weeks and evaluated at 5 points ; at baseline, and 1, 2, 4 and 8 weeks of treatment. The dose was increased from 2mg/day(1mg twice daily) to 6mg/day(3mg twice daily) during the first week and adjusted to a maximum of 16mg/day over the next 7 weeks according to the patient's clinical response. Medication to control extrapyramidal symptoms was permitted. The psychiatric and neurological status of the patients was assessed by PANSS, CGI, and ESRS scales. Results : 343(91%) of 377 patients completed the 8-week trial period. Clinical improvement, as defined by a 20% or more reduction in total PANSS score at end point, was shown by 81.3% of patients. The predictors of response to risperidone were associated older age, shorter duration of illness, fewer previous hospitalization. Risperidone had rapid onset of action ; a significant decrease of the total PANSS and three PANSS factor(positive, negative, general), and CGI was already noticed at the end of first week. For the ESRS, parkinsonism rating scores were significantly increased until week 4 comparing with baseline. Dystonia rating scores were significantly increased until week 1, and dyskinesia rating scores were not significantly changed during the study. Laboratory parameters including vital sign, EKG, hematological, and biochemical values showed no significant changes during the trial. Conclusions : This study suggests that risperidone is generally safe and effective against both the positive and negative symptoms in our group of patients.

수근관 증후군에서의 무증상성 척골신경병증

문준식,이성수,이지용,한범기,권준범,양현덕,이성익 대한신경과학회 1999 대한신경과학회지 Vol.17 No.2

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.

서울의 Penicillinase Producing Neisseria Gonorrhoeae 발생빈도(1996)

김재홍,황동규,전재홍,김윤석,김중환,김용준,이창균,임동진,김현수,조창근,김경문,박상훈,전우형,김희성,이호정,차명수,김갑형,김형석,김석우,황지환,박병순,권오상,이민수,송기훈,성소영,이인섭,부태성 대한화학요법학회 1999 대한화학요법학회지 Vol.17 No.2

Background : In recent years, gonorrhea has been panedemic and remains one of the most commom STDs in the world, especially in developing countries. Objective & Methods: For the detection of a more effective therapeutic regimen and assessing the prevalence of PPNG, we have been trying to study the patients who have visited the VD Clinic of Choong-Ku Public Health Center in Seoul since 1980 by means of the chromogenic cephalosporin method. Results: In 1996, 139 strains of N. gonorrhoeae were isolated, among which 53(39.0%) were PPNG. Conclusion: Our results suggests that after a peak of 74.3% in 1993, the prevalence of PPNG in Seoul is gradually declining.

미세혈관 수술후 Urokinase투여효과에 관한 실험적 연구

이세일,오석준,김용성,양경무 大韓成形外科學會 1987 Archives of Plastic Surgery Vol.14 No.1

However, even the most technically perfect anastomosis can neither eliminate the damage which microneedles cause on the vascular endothelium nor foreign body reaction to the suture material. Thrombosis developed at the suture site and regressed if the stimulus for the thrombosis is not severe. Partial thrombosis was inevitable after microvascular anastomosis. Since systemic thrombolytic drugs were used initially in the management of pulmonary emboli, urokinase were also used in prevention of thrombolysis and thrombolysis after microvascular anastomsis. This experimental study includes the effect of urokinase on the microvascular anastomosis in rabbits. The patency was observed, and platelet count, fibinogen, prothrombin time, and activated partial thromboplastim time were examined. In the case of thromboses, the anastomotic sites were resected and examined microscopically. The results were as follow; 1. The patency rate was increased 15 percent in experimental group than control group. 2. There were no differences in platelet count and the prothrombine time between experimental and control group. 3. The level of fibrinogen was decreased 157㎎/dl in experimental group less than control group. 4. The activated partial thromboplastin time was increased three to four times at postoperative period more than preoperative period in experimental group. 5. In light microscopic examination of thrombotic vessel wall revealed inflammatory reaction to suture material. In the experimental group, the thrombi were loose and defibrinated than control group.

動力耕耘機의 牽引 및 牽引補助裝置에 관한 硏究

李揆昇,李鎔國,朴濬傑 成均館大學校 科學技術硏究所 1983 論文集 Vol.34 No.1

The objectives of this study were i) to find the traction aids of power tiller, which can be used more efficiently for grassland, slope land and other soil surfaces on which power tiller have traction problems, and ii) to evaluate the comparative traction performance of two different. types of traction devices of rower tiller; tire and tire with traction aids (track). This experiment was carried out on the four different soil surfaces : hard soil surfaces, plowed land, soil covered with weeds and asphalt road. The results of this experiment were summarized as follows. 1) Power tiller with tires show maximum draft of 200kg at slip range of 40∼50% on four different soil surfaces. Power tiller with traction aids (track type rower tiller) reaches maximum draft of 300kg at about 50% slip on the soil covered with weeds and at 70% slip on the hard soil surface and plowed land. 2) Track type power tiller showed 1.6∼1.8 times as much maximum draft as fewer tiller with tire showed on the all soil surfaces on which experiment were carried out except asphalt road. 3) Track type power tiller showed maximum drawbar horse-power of 1.0∼1.5HP at 28∼35% slip for four different soil surfaces, when the draft was about 300Kg. Power tiller with tire reaches maximum drawl ar horsepower of 0.5∼1.0HP at 20∼25% slip with 200Kg of draft for four different soil surfaces. 4) Track type power tiller showed 1.6 times as much maximum drawbar horsepower as Lower tiller with tire showed. This means that track type rower tiller shows much better tractive efficiency compared with that of power tiller with tire.

칠절봉 신갈나무(Quercus mongolica)림의 군락구조와 토양환경

이호준,배병호,전영문,정흥락,홍문표,김용옥,길지현 建國大學校基礎科學硏究所 1998 理學論集 Vol.23 No.-

칠절봉 신갈나무림의 군락구조와 토양환경과의 관계를 파악하기 위해 식물사회학적 조사와 토양 환경을 분석하였다. 조사지역의 신갈나무림은 신갈나무군락, 철쭉꽃하위군, 큰개별꽃하위군으로 구분되었으며, 철쭉꽃하위군과 큰개별꽃하위군에서의 방형구당 평균출현종수는 각각 30종(24∼46종), 43종(31∼52종) 이었다. 피복지수치에 의한 계층별 우점순위는 교목층에서 신갈나무(6750.0), 아교목층에서 당단풍(2364.0) 관목층에서 철쭉꽃(988.5), 초본층에서 쌀새(1040.5)가 가장 높게 나타났다. 신갈 나무림의 DBH 분포는 2∼10㎝ 범위의 소경목이 전체의 29.7%를 차지하였으며 전체적으로 정규분포를 나타내어 교란 후 재생과정에 있는 것으로 조사되었다. 또한 후계목의 발달로 인한 극상상태로의 천이가 가능할 것으로 조사되었다. 전반적인 토양환경은 두 하위군 간에 뚜렷한 차이가 없었으며, 큰개별꽃하위군이 철쭉꽃하위군에 비하여 다소 양호한 것으로 조사되었다. 환경구배분석에서 까치박달, 물푸레나무, 함박꽃나무 등은 습한 곳에 분포하고 철쭉꽃, 전나무, 국수나무 등은 건조한 곳에 분포하는 것으로 나타났다. A relationship between the community structure composition and soil environmental factors of the Quercus mongolica forest on Mt. Chiljelbong was investigated from June 1996 to August 1997. The Q. mongolica community was classified into two subcommunity of Rhododendron schlippenbachii and Pseudostellaria palibiniana. The 30(24-46) species per quadrat were appeared in R. schlippenbachii subcommunity and 43(31-52)species in P. palibiniana subcommunity. The dominant sequences on each stratum determined by the coverage index showed that Q. mongolica was the most dominant in tree-1 layer with 6750.0, Acer pseudo-sieboldianum in tree-2 layer with 2364.0, R. schlippenbachii in shrub layer with 988.5, and Melica onoei in herb layer with 1040.5 value. The value of diameter breast height(DBH) showed a normal distribution displaying a highest value in the range of 2∼10㎝(29.7%) in Q. mongolica forest and it was investigated being at restoration phase after disturbance. It also was investigated that the succession to climax state would be possible due to growth of successive tree. Overall, which the soil conditions make little difference between two subcommunities, P. palibiniana subcommunity was favorable than those of R. schlippenbachii subcommunity. It was shown that in an environmental gradient analysis, Carpinus cordata, Fraxinus rhynchophylla, and Magnolia sieboldii were distributed in a mesic area, but R. schlippenbachii, Abies holophylla, and Stepanandra incisa in a xeric area.

안면골 골절에 관한 임상적 고찰

이상한,정용,김준연 慶北大學校 齒科大學 1988 慶北齒大論文集 Vol.5 No.1

This is a retrospective study on facial bone fractures. The study was based on a series of 418 patients with facial bone fractures during the period of Jan, 1981 to Dec. 1987. The results obtained were as follows; 1. The ratio of men to women 5.6:1, and then the age frequency was the highest in the second decade(43.5%) and patients from the first decade to the third decade were over 4/5 of total patients. 2. There is a rather seasonal patten of distribution of admissions of facial bone fractures over each 12months period with no statistical significance. 3. The most common location of facial bone fracture was mandible(73.6%), and zygoma complex(13.2%), maxilla(12.2%), and nasal bone(1.5%) were next in the order of frequency. 4. The most common etiologic factor of facial bone fractures was traffic accidents(39.2%), and the next factor in the order of frequency was fist blow(30.0%), falling down(19.6%).