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>

치근단낭과 육아종의 디지털방사선학적 비교연구

이건일,진연화 大韓口腔顎顔面 放射線學會 1999 Imaging Science in Dentistry Vol.29 No.1

The purpose of this study was to investigate whether a radiometric analysis of radicular cysts and periapical granulomas is useful in the differential diagnosis. In this experiment, twenty-nine periapical radiographs of the radicular cyst and those periapical granuloma were used. The periapical radiography was taken by intraoral paralleling device. The X-ray film was digitized and digitally filtered to reduce film-grain noise. We estimated density difference of the inner/outer area, roundness or circularity, bone profile or scan line of the margin and cumulative percentage frequency curve of radicular cyst & periapical granuloma. The obtained results were as follows; 1. The differences in density between ROIs of inner and outer area of radicular cysts were smaller than those of periapical granulomas. 2. The equivalent circular diameter was over 6.3mm, there was significant difference between periapical cyst and periapical granuloma. 3. In differential diagnosis of radicular cyst and periapical granuloma using bone profile, sensitivity, specificity and accuracy were considerable high(0.83, 0.86, 0.86) respectively. 4. Cumulative percentage frequency curve of the radicular cyst was closer to the pseudo-pixel value of 50 than average curve, whereas periapical granuloma was closer to that of 0. Hence we conclude that digital radiometric features might be useful in the differential diagnosis between radicular cyst and periapical granuloma.(J Korean Oral Maxillofac Radiol 1999:29:239-252)

계수공제영상의 비선형 대조도 증강효과에 관한 연구

이건일,진연화 大韓口腔顎顔面放射線學會 1997 Imaging Science in Dentistry Vol.27 No.2

This study was performed to demonstrate the effect of linear or nonlinear contrast enhancement on subtraction images. Three different textures were radiograped on dental film. The first radiograph was taken without the presence of and object. the second, which showed trabucular bone, was taken of the molar area of a human. the third radiograph was taken of the coronal part of molars. Each film was digitized into a 1312 x 1024 pixel x 8 bit depth matrix by means of a Nikon 35 mm film scanner(LS-3510AF, Japan) with fixed gain and internal dark current correction to maintain constant illumination. The scanner was interfaced to a Macintosh LC Ⅲ computer(Apple Computer, Charlotte, N.C.). This resulted in three pairs of images, including different textures-plain, bone and enamel. Digital regular, linearly and nonlinearly enhanced subtraction was performed. Computer software was used to simulate lesions in the shape of a 2D-Gaussian curve on each of a pair of images. The each subtraction images were presented in a random sequence to two groups of 10 observers(students and dentists). ROC analysis was used to compare observer performance. The following results were obtained; 1. All of LCE subtraction, equalized subtraction and regular subtraction images of plain texture were diagnosed the best by far. 2. The data revealed a significant LCE effect in both the student group and the expert group. 3. Clinical expertise was a helphul factor for the observers in this study.

Evaluation of the Public Health Emergency Response to the COVID-19 Pandemic in Daegu, Korea During the First Half of 2020

Hwa-Jin Lee,Keon Yeop Kim,Jong-yeon Kim,Sin Kam,Kyeong Soo Lee,Jung Jeung Lee,Nam Soo Hong,Tae-Yoon Hwang 대한예방의학회 2022 예방의학회지 Vol.55 No.4

Objectives: This study evaluated the response in Daegu, Korea to the first wave of the coronavirus disease 2019 (COVID-19) pandemic according to a public health emergency response model. Methods: After an examination of the official data reported by the city of Daegu and the Korea Centers for Disease Control and Prevention, as well as a literature review and advisory meetings, we chose a response model. Daegu’s responses were organized into 4 phases and evaluated by applying the response model. Results: In phase 1, efforts were made to block further transmission of the virus through preemptive testing of a religious group. In phase 2, efforts were concentrated on responding to mass infections in high-risk facilities. Phase 3 involved a transition from a high-intensity social distancing campaign to a citizen participation–based quarantine system. The evaluation using the response model revealed insufficient systematic preparation for a medical surge. In addition, an incorporated health-related management system and protection measures for responders were absent. Nevertheless, the city encouraged the participation of private hospitals and developed a severity classification system. Citizens also played active roles in the pandemic response by practicing social distancing. Conclusions: This study employed the response model to evaluate the early response in Daegu to the COVID-19 pandemic and revealed areas in need of improvement or maintenance. Based on the study results, creation of a systematic model is necessary to prepare for and respond to future public health emergencies like the COVID-19 pandemic.

Progression of Cerebral White Matter Hyperintensities and the Associated Sonographic Index

Lee, Woo-Jin,Jung, Keun-Hwa,Ryu, Young Jin,Lee, Keon-Joo,Kim, Jeong-Min,Lee, Soon-Tae,Chu, Kon,Kim, Manho,Lee, Sang Kun,Roh, Jae-Kyu Radiological Society of North America 2017 Radiology Vol. No.

Tocilizumab in Autoimmune Encephalitis Refractory to Rituximab: An Institutional Cohort Study

Lee, Woo-Jin,Lee, Soon-Tae,Moon, Jangsup,Sunwoo, Jun-Sang,Byun, Jung-Ick,Lim, Jung-Ah,Kim, Tae-Joon,Shin, Yong-Won,Lee, Keon-Joo,Jun, Jin-Sun,Lee, Han Sang,Kim, Soyun,Park, Kyung-Il,Jung, Keun-Hwa,Jun Springer-Verlag 2016 Neurotherapeutics Vol.13 No.4

<P>A considerable portion of autoimmune encephalitis (AE) does not respond to conventional immunotherapies and subsequently has poor outcomes. We aimed to determine the efficacy of tocilizumab, an anti-interleukin-6 antibody, in rituximab-refractory AE compared with other treatment options. From an institutional cohort of AE, 91 patients with inadequate clinical response to first-line immunotherapy and following rituximab were retrospectively reviewed. Patients were grouped according to their further immunotherapy strategies. Thirty (33.0 %) patients were included in the tocilizumab group, 31 (34.0 %) in the additional rituximab group, and 30 (33.0 %) in the observation group. Outcomes were defined as the favorable modified Rankin Scale scores (aecurrency sign2) at 1 and 2 months from the initiation of each treatment strategy and at the last follow-up. Favorable clinical response (improvement of the modified Rankin Scale scores by aeyen 2 points or achievement of the mRS scores aecurrency sign 2) at the last follow-up was also analyzed. The tocilizumab group showed more frequent favorable mRS scores at 2 months from treatment initiation and at the last follow-up compared with those at the relevant time points of the remaining groups. The majority (89.5 %) of the patients with clinical improvement at 1 month from tocilizumab treatment maintained a long-term favorable clinical response. No serious adverse effects of rituximab or tocilizumab were reported. Therefore, we suggest that tocilizumab might be a good treatment strategy for treating AE refractory to conventional immunotherapies and rituximab. The tocilizumab-mediated clinical improvement manifests as early at 1 month after treatment initiation.</P>

Early Prediction of Response to First-Line Therapy Using Integrated 18F-FDG PET/CT for Patients with Advanced/Metastatic Non-small Cell Lung Cancer

Lee, Dae Ho,Kim, Seok-Ki,Lee, Ho-Young,Lee, Sung Young,Park, Sun Hwa,Kim, Hyae Young,Kang, Keon Wook,Han, Ji-Youn,Kim, Heung Tae,Lee, Jin Soo Elsevier 2009 Journal of thoracic oncology Vol.4 No.7

<P>INTRODUCTION: Early prediction of treatment response is of great value to avoid unnecessary toxicity of ineffective treatment and to get a chance to receive another effective treatment earlier. We conducted a prospective study to evaluate the role of integrated 18-fluorodeoxyglucose positron emission tomography/computed tomography as a tool for early response predictor. METHODS: Between May 2004 and November 2005, 31 patients with pathologically proven stage IIIB/IV non-small cell lung cancer participated in this study. Metabolic response was assessed prospectively after one cycle of systemic therapy, which was compared with conventional radiographic response according to the World Health Organization criteria. RESULTS: By the World Health Organization criteria, 10 of 31 patients (32.3%) achieved a partial response, 7 stable diseases, and 14 progressive diseases, whereas there were 7 partial metabolic responses, 13 stable metabolic diseases, and 11 progressive metabolic diseases. Out of 7 partial metabolic responses, 5 achieved partial response, 1 stable disease, and 1 progressive disease (positive predictive value of 71.4% [5 of 7]), whereas 9 of the 11 progressive metabolic diseases had progressive diseases and the other 2 showed stable diseases (negative predictive value of 100% [11 of 11]). There were moderate correlation between early metabolic response and best overall response (Spearman r = 0.62, p < 0.01). However, an early metabolic response did not translate into better survival outcome. CONCLUSIONS: Single 18-fluorodeoxyglucose positron emission tomography/computed tomography scan taken after one cycle of treatment could predict progressive disease earlier than standard radiographic evaluation and can be used as a measure to avoid ineffective systemic chemotherapy.</P>

High Efficiency and ESD of GaN-Based LEDs With Patterned Ion-Damaged Current Blocking Layer

Keon Hwa Lee,Yong-Tae Moon,Seung Kyu Oh,Joon Seop Kwak IEEE 2015 Photonics Technology Letters Vol.27 No.2

<P>This letter examined the use of a patterned ion-damaged current blocking layer (patterned-IDCBL). A 50-Å-InGaN layer grown as the top epitaxial layer was transformed into an insulator fabricated by oxygen plasma treatment, in which the dot patterns are regularly arranged over the active areas of the light-emitting diode (LED) and inserted beneath the p-electrode. The results showed that the light output power increased by 16.8% at 60 mA compared with the conventional LEDs, and that the electrostatic discharge resistance is effectively improved by the patterned-IDCBL.</P>

Rituximab treatment for autoimmune limbic encephalitis in an institutional cohort

Lee, Woo-Jin,Lee, Soon-Tae,Byun, Jung-Ick,Sunwoo, Jun-Sang,Kim, Tae-Joon,Lim, Jung-Ah,Moon, Jangsup,Lee, Han Sang,Shin, Yong-Won,Lee, Keon-Joo,Kim, Soyun,Jung, Keun-Hwa,Jung, Ki-Young,Chu, Kon,Lee, Sa Ovid Technologies (Wolters Kluwer) - American Acad 2016 Neurology Vol.86 No.18

<P>Objective: To determine efficacy and safety of rituximab treatment as a second-line immunotherapy treatment for autoimmune limbic encephalitis (ALE) and to determine factors associated with functional improvement and favorable outcome following rituximab treatment. Methods: We recruited 80 patients with ALE who were treated with rituximab as a second-line immunotherapy from the Korea Autoimmune Synaptic and Paraneoplastic Encephalitis Registry and reviewed 81 patients without rituximab as a control. We grouped patients according to the detection or type of antibodies; in addition, we evaluated clinical, laboratory, first-line immunotherapy, and rituximab treatment profiles and defined main outcomes as improvements on the modified Rankin Scale (mRS) score and a favorable mRS score (0-2) at the last follow-up. Results: Functional improvement occurred more frequently in the rituximab group compared to the control group. In the rituximab group, 30 (37.5%) patients had synaptic autoantibodies, 15 (18.8%) in the paraneoplastic autoantibodies, and 35 (43.8%) were antibody-negative. The effect of rituximab was the same regardless of autoantibody status. Additional monthly rituximab therapy and partial response to first-line immunotherapies were associated with mRS score improvements, as well as favorable mRS scores. mRS scores of 4-6 as the worst neurologic status predicted an unfavorable mRS score. There were no reported serious infusion-related or infectious adverse effects of rituximab. Conclusions: Rituximab is effective and safe as a second-line immunotherapy for ALE, regardless of autoantibody status. Additional monthly rituximab therapy might potentiate the efficacy of rituximab. Classification of evidence: This study provides Class IV evidence that rituximab improves mRS scores for patients with autoimmune limbic encephalitis who fail first-line therapy.</P>

UML을 이용한 컴포넌트 재사용을 위한 인터페이스 명세 시각화 방법

이건화(Keon-hwa Lee),김강태(Kang-tae Kim),이경환(Kyung-whan Lee) 한국정보과학회 1999 한국정보과학회 학술발표논문집 Vol.26 No.2Ⅰ

컴포넌트 재사용을 위해서 필요한 정보를 제공하는 일반적인 방법으로 인터페이스를 명세한다. 그러나 일반적인 인터페이스 명세는 단순히 외부적인 관점에서만 표현하므로, 컴포넌트간의 상호작용과 협력관계를 나타내지 못한다. 그러므로 컴포넌트 개선(evolution) 및 합성(composition)시에 발생할 수 있는 문제점(conflict)에 대한 충분한 정보를 제공할 수 없다. 본 논문에서는 외부적으로 요구되는 컴포넌트 인터페이스뿐만 아니라 각 컴포넌트 사이에 발생하는 상호작용을 나타낼 수 있는 방법으로 기존의 계약(contract) 개념을 바탕으로 컴포넌트에 적합하도록 변형하여 이를 시각화하였다. 시각화를 위해서 일반적인 산업표준으로 자리잡아가고 있는 UML의 확장 메커니즘의 하나인 stereotype을 이용하여 기본 컴포넌트 계약 재사용 타입을 나타내고 정의하였다. 그리고 재사용 타입간의 관계를 통하여 컴포넌트 개선 및 합성시에 발생할 수 있는 문제점을 지적하고 이를 감지하는 방법을 제공했다.