두 종류의 스펙트럼영역 빛간섭단층촬영기를 사용한 정상 한국인의 맥락막 두께 측정의 재현성

이광현,이성철,이승규.Kwang Hyun Lee. MD. Sung Chul Lee. MD. Christopher Seungkyu Lee. MD 대한안과학회 2013 대한안과학회지 Vol.54 No.9

Purpose: To investigate the reproducibility of choroidal thickness measurements in healthy Koreans using two spectral domain optical coherence tomography (SD-OCT) instruments: Zeiss Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA, USA) and Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany). Methods: Images were obtained in 60 eyes of 30 healthy undilated volunteers without ocular pathology in a clinical setting. The choroid was imaged in all subjects using Cirrus HD 1-line raster and Spectralis enhanced depth imaging (EDI). The choroid was measured subfoveally, 1500 μm temporal, and 1500 μm nasal to the fovea. All measurements were performed by two independent observers. One-way analysis of variance (ANOVA), Pearson correlation, and Bland–Altman analysis were used to compare measurements. Results: The study group consisted of 15 males and 15 females. The mean age was 50.73 ± 15.09 years (range, 24-75 years). There was no significant difference in the mean choroidal thickness (p > 0.05) between systems for any location. The choroidal thickness measurements using two instruments (Cirrus vs. Spectralis) were also strongly correlated (p < 0.001). Conclusions: In the present study of healthy Korean adults, good reproducibility was observed between choroidal thickness measurements of images obtained from Cirrus and Spectralis.

Application in Ultrafiltration and Reverse Osmosis Module Set with Acrylic Wastewater Pretreated by Coagulation-Filtration-Neutralization Process

이광현,강병철,이종백,Lee, Kwang-Hyun,Kang, Byung-Chul,Lee, Jong-Baek The Membrane Society of Korea 2008 멤브레인 Vol.18 No.1

After membrane fouling factors in acrylic wastewater were minimized by pretreatment process accompanied with coagulation-filtration-neutralization, it was utilized in UF/RO process. After composing of ultrafiltration and reverse osmosis module set according to types and kinds of membrane, the separation characteristics were examined with the variation temperature and pressure using pretreated acrylic wastewater by membrane module sets. It was found that permeate flux of UF module in module set 4 was about two${\sim}$three times larger than that of UF module in module set 1. Final quantity of permeate from the module set 2 and module set 3 combined with tubular module was shown very good result. It was shown that the removal efficiency of TDS, T-N and COD was very low and was not dependent on the variation of temperature and pressure in all UF modules. The removal efficiency of TDS, T-N and COD was very excellent in RO module. Final water quality of acrylic wastewater was satisfied with effluent allowances limit and membrane module sets were ascertained to reuse wastewater. 아크릴 폐수를 응집-여과-중화의 전처리 공정에 적용하여 막오염 인자를 최소화 한 후 UF/RO 공정에 적용하였다. 막의 형태 및 종류에 따라 한외여과 및 역삼투 모듈을 조합을 이루어 전처리 수를 온도 및 압력변화에 따라 적용하여 분리 특성을 고찰하였다. 투과 플럭스는 모듈 set 1의 UF모듈보다 모듈 set 4의 UF모듈의 투과량이 약 $2{\sim}3$배 더 많이 배출됨을 확인하였다. 최종적인 투과량은 관형모듈과 조합을 이룬 모듈 set 2와 모듈 set 3이 좋은 결과를 나타내었다. 모든 UF 모듈에서 TDS, T-N 및 COD의 제거 효율은 온도 및 압력변화에 영향을 받지 않고 제거 효율 또한 낮음을 알 수 있었다. RO모듈에서 TDS, T-N 및 COD가 우수한 제거 효율을 보였다. 아크릴 폐수의 최종적인 수질결과는 공장폐수의 배출 허용기준을 만족하였고, 막모듈 조합은 폐수의 재활용 가능성을 확인할 수 있었다.

자동차 주행 환경에서의 음성 전달 명료도와 음성 인식 성능 비교

이광현,최대림,김영일,김봉완,이용주,Lee Kwang-Hyun,Choi Dae-Lim,Kim Young-Il,Kim Bong-Wan,Lee Yong-Ju 대한음성학회 2004 말소리 Vol.50 No.-

The normal transmission characteristics of sound are hardly obtained due to the various noises and structural factors in a running car environment. It is due to the channel distortion of the original source sound recorded by microphones, and it seriously degrades the performance of the speech recognition in real driving environments. In this paper we analyze the degree of intelligibility under the various sound distortion environments by channels according to driving speed with respect to speech transmission index(STI) and compare the STI with rates of speech recognition. We examine the correlation between measures of intelligibility depending on sound pick-up patterns and performance in speech recognition. Thereby we consider the optimal location of a microphone in single channel environment. In experimentation we find that high correlation is obtained between STI and rates of speech recognition.

자동차 환경에서의 노이즈 DB 및 한국어 음성 DB 구축

이광현,김봉완,이용주,Lee Kwang-Hyun,Kim Bong-Wan,Lee Yong-Ju 대한음성학회 2003 말소리 Vol.48 No.-

Researches into robust recognition in noise environments, especially in car environments, are being carried out actively in speech community. In this paper we will report on three types of corpora that SiTEC (Speech Information TEchnology & industry promotion Center) has created for research into speech recognition in car noise environments. The first is the recordings of 900 Korean native speakers, distributed according to gender, age, and region, who uttered application words in car environments. The second is the collections of mixed noise in 3 car types by model while setting up various noise patterns which can be obtained with the car engine on or off, at different driving speed, and in different road conditions with windows open or closed. The third is the recordings of simulated speech by HATS (Head and Torso Simulator) in car environments with the internal and external noise factors added. These three types of recordings were all made through synchronized 8 channel microphones that are fixed in a car. The creation and applications of these corpora will be reported on in detail.

카올린나이트로부터 중기공성 ${\gamma}-Al_2O_3$의 제조 및 특성

이광현,고형신,김윤섭,Lee, Gwang-Hyeon,Go, Hyeong-Sin,Kim, Yun-Seop 한국재료학회 2000 한국재료학회지 Vol.10 No.12

국내산 kaolinite를 소성한 다음 실리카를 선택적으로 추출하여 중기공성 ${\gamma}-Al_2O_3$를 제조하였다. $1000^{\circ}C$에서 24시간 소성된 kaolinite는 소량의 무정형 실리카와 ${\gamma}-Al_2O_3$으로 이루어진 스피넬 상의 미세구조로 전이되었음을 확인하였다. 다공성 ${\gamma}-Al_2O_3$는 $25~90^{\circ}C$의 반응온도, 0.5~4h의 추출시간 및 1~8M의 KOH 농도범위에서 무정형 실리카를 선택적으로 용해하여 제조할 수 있었다. $90^{\circ}C$, 1시간 및 4M의 KOH 농도조건에서 얻어진 ${\gamma}-Al_2O_3$는 약 $40~80{\AA}$ 정도의 매우 좁은 하나의 기공크기 분포를 가지고 있었으며, mesopore의 기공이 많이 생성되었다. 비표면적은 $250\textrm{m}^2/g$이고, 총 기공부피는 $0.654\textrm{cm}^3/g$로 나타났다. Mesoporous ${\gamma}-Al_2O_3$ has been prepared by selective leaching of silica from calcined domestic kaolinite. From XRD and TG-DTA data, it was found that the microstructure of a spinel phase, consisting of ${\gamma}-Al_2O_3$ containing a small mount of amorphous silica, was obtained by calcining kaolinite samples at around $1000^{\circ}C$ for 24h. Porous ${\gamma}-Al_2O_3$ was prepared by selectively dissolving the amorphous silica in KOH solutions of 1~4M at temperatures of $25~90^{\circ}C$ for leaching time of 0.5~4h. In the case of the ${\gamma}-Al_2O_3$ obtained upon KOH treatment of 4M at $90^{\circ}C$ for 1h, it showed a very narrow unimodal pore size distribution, and also formed much mesopore at a diameter of around $40~80{\AA}$. The specific surface area was $250\textrm{m}^2/g$ and the total pore volume was $0.654\textrm{cm}^3/g$.

저전력 설계를 위한 전달된 Booth 곱셈기 구조

이광현,박종석,Lee, Kwang-Hyun,Park, Chong-Suck 대한전자공학회 2000 電子工學會論文誌-SD (Semiconductor and devices) Vol.37 No.9

본 논문에서는 DSP등에서 응용될 수 있는 저전력 곱셈기를 제안하다. 많은 DSP 러풀리케이션에서 곱셈기의 모든 출력을 사용하는 것이 아니라, 그중 상위 비트만을 취해서 사용한다. Kidambi는 이런 개념에 기본하며 절단된 곱셈기를 제안하였다. 본 논문에서는 이 개념을 실제로 사용이 가능한 Booth 곱셈기에 적용한다. 이전 논문에서는 고려하지 않은 0 입력에 대한 0 출력을 보장하였다. 그리고, 비트수 확장법을 제안하여 더욱더 오차를 감소시켰다. 그리고, 이 필터를 FIR 필터 설계에 적용하여 더욱 효율적으로 회로를 구성할 수 있음을 확인하였다. In this paper, we propose a hardware reduced multiplier for DSP applications. In many DSP applications, all of multiplier products were not used, but only upper bits of product were used. Kidambi proposed truncated unsigned multiplier for this idea. in this paper, we adopt this scheme to Booth multiplier which can be used real DSP systems. Also, zero input guarantees zero output that was not provided in previous paper. In addition, we propose bit extension scheme to reduce truncation error more and more. And, we adopted this multiplier to FIR filters for more efficient design.

천연 제올라이트와 제올라이트 담체를 이용한 NH₄⁺-N 이온교환 특성 평가

이광현,박민석,주현종,Lee, Kwang Hyun,Park, Min Suk,Joo, Hyun Jong 한국물환경학회 2009 한국물환경학회지 Vol.25 No.5

The ammonium ion exchange characteristics of natural zeolite were investigated to remove ${NH_4}^+-N$. The effect of water temperature, particle size and competitive cation on the exchange capacity was examined. Ammonium ion exchange capacity tended to decrease when the temperature increased from $25^{\circ}C$ to $40^{\circ}C$. Exchange capacity was increased according to the particle size of natural zeolite comes to be small. Batch isotherm experiments were conducted for measuring ammonium ion exchange capacity. The ion exchange capacity was well described either by the Langmuir isotherm model or by the Freundlich isotherm model. The ammonium ion exchange capacity ($q_m$) of zeolite carrier can be calculated $11.744mg-{NH_4}^+/g$-carrier. The ion exchange capacity of manufactured zeolite carrier was showed a similar tendency as ion exchange capacity of powder-sized natural zeolite. Therefore, zeolite carrier can be used for increasing of nitrogen removal efficiency in the wastewater treatment plants.

근적외선 연속발진 레이저 조사에 의한 게르마늄 광학창 손상 연구

이광현,신완순,강응철,Lee, Kwang Hyun,Shin, Wan-Soon,Kang, Eung-Cheol 한국군사과학기술학회 2014 한국군사과학기술학회지 Vol.17 No.1

The damage in germanium (Ge) optical window irradiated by a near-infrared continuous wave (CW) laser was studied. Laser-induced heating and melting process were surveyed, and the specific laser power and the irradiance time to melt were estimated by numerical simulation. The experiments were also carried out to investigate the macro and micro structure change on Ge window. Results showed that the surface deformation was formed by melting and resolidification process, the damaged surface had a polycrystalline phase, and the transmittance as an optical performance factor in mid-infrared region was decreased. We confirmed that an abnormal polycrystalline phase and surface deformation effect such as hillock formation and roughness increase reduced the transmittance of Ge window and were the damage mechanism of CW laser induced damage on Ge window.

수부에 발생한 지방종성 종양

이광현,이봉근,봉현종,Lee, Kwang-Hyun,Lee, Bong-Gun,Bong, Hyun-Jong 대한근골격종양학회 2008 대한골관절종양학회지 Vol.14 No.2

목적: 지방종성 종양은 수부에서 발생하는 경우는 드문 것으로 알려져 있다. 저자들은 수부에 발생한 지방종성 종양 11예를 수술적으로 치료하였기에 그 임상적 특성을 보고하고자 한다. 대상 및 방법: 1992년부터 2008년까지 수부종양으로 수술받았던 환자 중 조직학적으로 지방종성 종양으로 진단받은 환자를 선별하였으며 후향적으로 그 특성을 조사하였다. 의무기록 및 방사선학적 검사 그리고 수술전후 사진기록을 조사하였다. 재발여부는 전화면담을 통해 확인하였다. 결과: 11예 중 8예가 지방종이었으며 비전형 지방종(atypical lipoma)가 1예, 조갑하 혈관 지방종(subungal angiolipoma)가 1예, 섬유지방종(fibrolipoma)이 1예이었다. 발생부위로 수지에 발생한 경우가 4예이었으며 무지구근부 2예, 소지구근부 2예, 수장부 1예, 손목 2예이었다. 전례에서 수장부에 발생하였다. 증상으로 대부분 종물감을 호소하였으며, 통증이 동반된 경우는 2예, 감각이상을 호소한 경우가 1예 있었다. 통증이 있었던 2예 중 1예는 조갑하 혈관지방종이었고 1예는 수장부에 발생한 단순 지방종이었다. 비전형 지방종은 2 cm 가량의 주위조직을 포함한 광범위 절제를 시행하였고, 나머지 10예에서는 단순 절제를 시행하였다. 술 후 합병증으로 지방종의 크기가 5 cm이상으로 수술 후 수술부의 원위부에 감각저하 및 수술 절개부에 과감각을 호소하는 경우가 1예 있었고 기타 다른 합병증은 없었다. 전화면담이 가능했던 10예 중 재발은 없었다. 결론: 수부에 발생하는 지방종성 종양은 대개 종물감외에는 증상이 없으나 드물게 통증이 나타나는 경우가 있었다. 육안 소견은 비슷하나 조직의 성상은 다양하였다. 수술을 할 경우 합병증의 위험은 적으나 종괴가 클 경우 수술 중 신경손상의 위험이 있으므로 세심한 수술을 해야 할 것으로 사료된다. Purpose: Lipomatous tumor occurred in hand is very rare. There is a broad spectrum of lipomatous tumors including lipomas, variants of lipomas, lipomatosis, liposarcomas and so on. We report the clinical features of 11 cases of lipomatous tumor which occurred in hand. Materials and Methods: Between 1992 and 2008, 11 cases were histologically diagnosed as lipomatous tumor in hand. We reviewed all medical records and clinical photographs retrospectively and ascertained recurrence by telephone interview. Results: Eight cases were ordinary lipomas. Three cases were angiolipoma, fibrolipoma and atypical lipoma respectively. Four cases occurred in finger, two cases in thenar area, two cases in hypothenar area, one case in palm, two cases in wrist. All cases were situated on volar surface. All patients complained of palpable masses. One patient with subungal angiolipoma felt pain. There was no neurologic sign or vascular symptom preoperatively. In one case, postoperative complication (hypoesthesia in $5^{th}$ finger) was developed. There was no local recurrence. Conclusion: In our study, lipomatous tumors occurred in hand did not recur. Patients mainly complained of feeling of lump. Pain was uncommon symptom. Postoperative complication was rare if operation was performed carefully.

서버 부하 감소를 위한 P2P 기반 데이터 서비스 시스템의 설계 및 구현

이광현,전형수,유철중,장옥배,Lee, Kwang-Hyon,Jeon, Hyung-Su,Yoo, Cheol-Jung,Chang, Ok-Bae 한국정보처리학회 2002 정보처리학회논문지 C : 정보통신,정보보안 Vol.9 No.5

최근 흠 네트워킹에 대한 관심이 증가하면서 멀티미디어 클립서비스에 관한 연구가 진행되고 있다. 가정내 네트워크의 대역폭이 가지는 한계로 인해 클라이언트-서버 방식을 통한 대용량 멀티미디어 자료들을 장시간 동안 받아야하고 서버에 트래픽이 증가하는 문제점들이 나타나고 있다. 본 논문에서는 서버를 거치지 않고 가정과 가정을 직접 연결하여 자료를 교환할 수 있는 Peer-to-Peer(P2P) 기술이 적용된 자료공유 네트워크 시스템을 설계하였고 서버의 트래픽을 줄이도록 하였으며 Java 언어로 플랫폼 독립적인 시스템을 구현하였다. Recently, as interest in Home networking is increased, research about multimedia clip service is gone. Because of the limit to bandwidth of home network, the problem of server traffic is increased by transferring many multimedia data through Client-Sewer Way for long. The data share network system applied is designed and implemented to solve this problem. P2P is connected directly between clients and exchanges data without going through a sewer. We implemented platform-independent System using Java and applied P2P skill to reduce server traffic.