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>

업종에 따른 연 취급 사업장의 기중 연 농도 및 연 노출 수준 평가

이병국,김용배,리갑수,안현철,김화성,이용진,황규윤,장봉기,이성수,안규동 순천향대학교 산업의학연구소 1999 순천향산업의학 Vol.5 No.1

In order to obtain an useful information for health management and biological monitoring of lead exposed workers, Authors tried to investigate air lead level and the lead exposed level of workers in lead industry according to occupational category. The subjects in our study were 2074 workers in 7 lead-using industries, and study subjects were divided into 4 occupational categories such as storage battery industry (type 1), primary smelting industry (type 2), secondary smelting industry (type 3) and litharge making industry (type 4). Blood zincprotoporphyrin concentration (ZPP), blood lead concentration (PbB) and urinary δ -aminolevulinic acid (ALAU), hemoglobin (Hb), hematocrit (Hct) were selected as the indices of lead exposure. Personal variables such as age, work duration were also collected. The results were as follows. 1. The geometric mean air lead in 9 lead-using industry was 0.1133±4.3120 ㎎/㎥, and that in type 1, 2, 3 and 4 was 0.1038±3.4952 ㎎/㎥, 0.0429±3.4329 ㎎/㎥, 0.1877±2.5123 ㎎/㎥ and 0.9961±5.2910 ㎎/㎥, respectively. 2. The mean ZPP in 9 lead-using industry was 53.1±28.0 ㎍/㎗, and that in type 1, 2, 3 and 4 was 52.0±24.8 ㎍/㎗, 48.0±16.4 ㎍/㎗, 109.8±85.6 ㎍/㎗ and 74.3±37.8 ㎍/㎗, respectively. There was significant difference in ZPP according to occupational category (P<0.01). The percents of lead workers whose ZPP were above 100 ㎍/㎗ in type 1, 2, 3 and 4 were 4.0%, 1.7%, 34.3% and 21.6%, respectively. 3. The mean PbB in lead-using industry was 26.0±11.2 ㎍/㎗, and that in type 1, 2, 3 and 4 was 25.3±11.1 ㎍/㎗, 26.7±8.8 ㎍/㎗, 50.3±15.2 ㎍/㎗ and 36.4±11.0 ㎍/㎗, respectively. There was significant difference in PbB according to occupational category (P<0.01). The percents of lead workers whose PbB were above 40 ㎍/㎗ in type 1, 2, 3 and 4 were 10.4%, 7.7% 71.9% and 43.2%, respectively. 4. While the correlation of Hb corrected PbB with ZPP was higher than non corrected PbB, the correlation of log-transformed ZPP with PbB was higher than non corrected ZPP. 5. Simple linear regressions of PbB and corrected PbB as independent variable with ZPP, log-transformed ZPP and ALAU as dependent variable were statistically significant (P0.01). Coefficient of determination of corrected PbB with other variables was higher than non corrected PbB. As the result of this study, it was suggested that reconsideration of environmental and biological monitoring program was highly recommended for secondary smelting and litharge making industry.

최신토지피복자료를 이용한 대구시의 열환경 수치모의

이현주(Hyun-Ju Lee),이귀옥(Kwi Ok Lee1),원경미(Gyeong Mee Won),이화운(Hwa Woon Lee) 한국대기환경학회 2009 한국대기환경학회지 Vol.25 No.3

Plant regeneration from callus of Iris odaesanensis Y. N. Lee native to Korea via organogenesis

Bae, Kee-Hwa,Yoo, Kyoung-Hwa,Lee, Mi-Hyun,Jeong, Jae-Hun,Choi, Yong-Eui,Yoon, Eui-Soo The Korean Society of Plant Biotechnology 2013 식물생명공학회지 Vol.40 No.3

Iris odaesanensis Y. N. Lee. is an important endangered and native plant belonging to the family Iridaceae in Korea. This study describes a method for rapid micropropagation of this species via from leaf, rhizome and root explants derived calli. Leaf, rhizome and root explants were cultured on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxy acetic acid (2,4-D) for callus induction. Rhizome explants yielded calli at a frequency of 72% when cultured at 1.0 mg/l 2,4-D. Calli were maintained at 1.0 mg/l 2,4-D. These calli were transferred to MS medium supplemented with 0, 0.5, 1.0, and 2.0 mg/l 2,4-D in combination with 0, 0.5, 1.0, and 3.0 mg/l BA for adventitious shoot induction. The highest number of adventitious shoot (228.9 per petri-dish) were formed at 1.0 mg/l 2,4-D and 1.0 mg/l BA. WPM medium was the best to convert calli into plantlets, where up to 98.2% of calli were regenerated into plantlets. This in vitro propagation protocol should be useful for conservation of this endangered plant.

간호실무에서 신봉이론(Espoused theories)에 대한 탐색적 연구

서문자,김혜숙,이은희,박영숙,조경숙,강현숙,임난영,김주현,이소우,조복희,이명하,지성애,하양숙,손영희,권성복,김희진,추진아 성인간호학회 2001 성인간호학회지 Vol.13 No.1

As a nursing practice involves nurses' actions in a specific context of health care, this study has focused on exploring the espoused theories in nursing practice within the action science perspectives, Espoused theories are the belief, principles, and rationale expressed by the practitioner as guiding her/his actions in a situation of practice. The data were analysed qualitatively and 25 elements of espoused theories of nursing action were identified and clustered into 6 categories. The 25 elements of espoused theories are as follows: The clinical nurse worked in wholistic and individual nursing, focussed on the patient's needed, comfort and supportive nursing (5 theories of nursing goal) ; excellent skills, knowledge based, assessment and data collection, explaining, educating or a scientific basis(6 theories of nursing intervention): advocacy, value oriented, treatment, account- ability and commitment(4 theories of nursing ethics) ; human respect. partnership, trust(3 theories of patient-nurse relationship) : knowledgable, accumulated clinical experiences and personally lived experiences. positive perspectives(4 theories of nurse), role of intervention. rewarding peer relationship(3 theories of situations) The above mentioned espoused theories are similar to that of nursing textbooks which students learned through basic nursing education and almost the same as the Acts ofa Nurse in Korean. However, we are doubtful whether nurses actually do as they think. Therefore. it is recommended to review the theories-in-use in order to and any discrepancies between the espoused theories and the reality of nursing actions

VOD 서비스에서의 새로운 스트림 할당 기법

이준화,김영환,박재현,박현민,최병석 明知大學校 産業技術硏究所 1999 産業技術硏究所論文集 Vol.18 No.-

Generally, in a VOD(Video On Demand) systems, batching technique is often used to improve throughput. Since subscribers to VOD services tend to renege their requests as the latency becomes large, an optimal stream allocation scheme should consider not only batching size but also renege rate, service latency and fairness between different programs. In this paper, we propose a new stream allocation scheme, which shows improvement in fairness and reduction in renege rate and service latency compared with other well known schemes. When 2 or more streams are available in the VOD server, each streams are allocated based on different program selection policies. Using this approach effectiveness of stream usage can be improved.

SED유출모델의 미계측유역에의 적용

이영화,조현경 慶山大學校 1997 論文集 Vol.15 No.1

An objective for this study is to apply a SED runoff model and identify its applicability in a ungauged watershed. Since there is no observation value, Tank model is used as a comparison subject which its applicability has been identified. We obtained the parameters of the models by the trial and error method. The SED runoff model predicted a runoff from Banbyun-chun watershed in Nakdong river basin. Although the peak flow of SED model was a bit less than the one of Tank model, the hydrographs of SED model and Tank model were showed a similar shape. Accordingly, the SED model shows a good applicability in ungaugred watershed.

peat moss를 이용한 폐수중의 중금속 제거

이경화,김정섭,유현철,최성우,윤철종,우성훈,박승조 동아대학교 환경문제연구소 2001 硏究報告 Vol.24 No.1

Adsorption equilibrium of heavy metals ion on the peat moss was confirmed Frundlich isotherm Removal efficiency of heavy metals ion was increased from pH 2 to 10 and heavy metal removal efficiency was increased in the sequence of Cu(Ⅱ) > Pb(Ⅱ) > Cd(Ⅱ) > Mn(Ⅱ) on the PM(Peat Moss). The PM is likely to be more effective adsorption than the PAC to removal of metal ions in the solution, since PM's weakly acidic functional groups which is not founded on the PAC, in addition to its high surface area and porosity. But, the PM is not separated from the solution water by sedimentation process. So, a liquid and solid seperation between the PM and the solution water could be considered for the PM's field application. But peat moss was low cost adsorbent. Thus author propose to adopt PM as a adsorbent for heavy metal removal.

Crown화합물과 분광광도법에 의한 미량 납의 분리 및 분석

이화구,한현택,정창웅 순천향대학교 기초과학연구소 1999 순천향자연과학연구 논문집 Vol.5 No.2

Ion-pair extraction of lead(Ⅱ) form varying concentration of HCI solution was studied employing crown ether in nitrobenzenc as the extractant. Lead(Ⅱ) complex was stripped into alkaline solution and Pb(DDTC)₂complex was replaced quantitatively with Cu(Ⅱ), this complex has maximum absorbance at 450㎚. Beer's law applied in the range of 1.5 ∼ 7.5 ㎍/mL of Pb(Ⅱ) and molar absorptivity is 8.3 × 10³L/mole·㎝.

일회통과 관류실험시 물의 수송 : 관류액의 종류와 삼투압의 영향 Effects of Some Perfusates and Their Osmolality

이정화,이현주,용철순,오두만 영남대학교 약품개발연구소 1995 영남대학교 약품개발연구소 연구업적집 Vol.5 No.-

The single pass perfusion experiments were performed in anesthetized rata to investigate the effects of perfusates and their osmolality on the water transport and to determine the correlation between the extent of water transport and the volume change of perfusate. Phenol red was used as a nonabsorbable marker. In normal rats, when perfused at a flow rate of 0.5 ml/min 2-(N-morpholino) ethanesulfonic acid (MES) aid Sorensen's phosphate hullers showed minimal net water transport as 0.125 and 0.173 %/cm of intestinal length, respecetively. Hypotonic perfusate of 200 mOsm㎏ of water and hypertonic perfusate of 400 mOsm/㎏ of water generated significant water transport compared with isotonic perfusate of 300 mOsn/㎏ of water. There was a linear correlation between the attent of water transport and the volume change of perfusate, suggesting that the volume change can be used as a measure of water transport.