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CW 0.5-W 1.52-㎛ Digital Alloy AlGaInAs-InP Multiple-Quantum-Well Lasers
DuChangHeo,송진동,한일기,JungIlLee,JiChaiJeong,JongMinKim,YongTakLee 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.1
AlGaInAs/InGaAs multiple-quantum-well (MQW) 1.52-$\mu$m laser diodes are fabricated. The AlGaInAs barrier is grown by using a digital alloy molecular beam epitaxy technique and is lattice-matched to InP. An internal loss of 13 cm$^{-1}$, an internal quantum efficiency of 41 \%, and a threshold current density of 0.88 kA/cm$^2$ are obtained from broad-area lasers. The characteristic temperature is constant at 70 K up to 50 $^\circ$C and then decreases to 60 K in the range of 50 $\sim$ 90 $^\circ$C. A single-uncoated-facet CW output power as high as 0.5 W is demonstrated, which is the first room-temperature operation of the digital alloy 1.5-$\mu$m AlGaInAs material system.
자연과학편 : 무용전공 여대생의 전공별 섭식장애 및 식이행동의 비교
김부용(BooYongKim),김기진(KiJinKim),이정일(JungIlLee) 한국체육학회 2007 한국체육학회지 Vol.46 No.6
본 연구는 무용전공 여대생의 섭식장애 및 식이행동의 특성을 파악하고 전공별 비교를 통해 바람직한 식이습관 마련을 위한 근거를 제시하고자 함에 있다. 대구·경북권 3개 대학교의 무용전공 여자 대학생 중, 발레 전공 61명, 현대무용 전공 67명 및 한국무용 전공 63명, 총 191명을 연구대상으로 하였다. 본 조사 결과, 무용전공 여대생 중 57.1%가 저체중이며, 45.1%가 섭식장애 위험군으로 분류되어 여대생 무용수들이 심각한 섭식장애에 노출되어 있음을 짐작할 수 있다. 섭식장애 위험의 발생빈도에 대한 교차분석 결과, 전공별에는 유의한 차이가 없었으며, 신체질량지수 기준 정상군과 저체중군 간 빈도에서도 유의한 차이가 없는 것으로 나타났다. 그러나, 발레 45.9%, 현태무용 53.7%, 한국무용 45.0%가 섭식장애 위험군으로, 발레전공 67.2%가 저체중군으로 분류되었다. 섭식장애와 식이행동의 평균 점수에 전공별에는 유의한 차이가 없는 것으로 분석되었으나, 무용전공 학생 전체의 정상군과 섭식장애 위험군 간에는 유의한(p<0.05) 차이가 있는 것으로 나타남으로써, 학생들의 섭식태도에 문제가 있으며 섭식장애의 중요한 원인인 것으로 간주되었다. 무용전공 학생 전체에서 식이행동의 절제와 외부적 섭식태도가 정서적 섭식태도보다 섭식장애에 더 유의하게 영향을 미치는 것으로 분석되었다. 본 연구에서 나타난 바와 같이 대학 무용수들은 심각한 식이장애의 위험에 노출되어 있으며 그 원인이 되는 섭식태도가 서로 다르게 나타나고 있다. 따라서 섭식장애의 위험을 줄이기 위한 노력이 필요한 것으로 생각된다. The purpose of this study was to obtain the basic information of eating disorder in female college dancers. Personal data for 191 students of female college dancers from three universities m Daegu and Gyeongbuk province were collected by using EAT-26 and DEBQ questionaires. These data were analyzed by a series of statistical analyses. The findings of the study were as follows: 57.1% of female college dancers belongs to the group of low body weight, and 45.1% is susceptible to eating disorder. Therefore, a lot of female college dancers are considered to subjects of potential eating disorder. Prevalence of eating disorder subjects or low BM subjects showed no statistical differences among detailed dancers. The eating disorder scores and eating behaviour showed a statistical differences between normal and eating disorder groups in entire subjects. This means that college dancers have abnormal eating behaviors and the such eating behaviors might be a cause of potential eating disorder. The restrained and external eating behaviours were considered a higher effect on potential eating disorder than the emotional eating behaviour in college dancers. This study suggested a serious eating disorder of college dancers, therefore we must emphasize an importance of normal eating habit for healthful life in college dancers.
Threshold Current Increase in GaAs/AlGaAs Quantum Cascade Lasers due to the Thickness Variation
한일기,Jeong, Jin-Wook,송진동,JungIlLee 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.4
GaAs/AlGaAs quantum cascade laser (QCL) epi-structures were grown and lased successfully at 77 K. The thickness variation during the growth sequence was measured by analyzing the transmission electron microscope pictures. The thickness of the epi-layer decreased by up to 80 90 % of its expected value. At least three times higher threshold current and shorter lasing wavelength, compared to the reference QCL, were shown. The decrease in the growth rate during the growth sequence is thought to be a possible reason for such a high threshold current and short lasing wavelength.
Development of De Novo Cavernous Hemangioma after Radiosurgery for Cavernous Hemangioma
Jung-Il Lee,Yeon-Lim Suh,Jong-Hyun Kim,이정일 대한신경외과학회 2010 Journal of Korean neurosurgical society Vol.48 No.12
We report a rare case of cavernous hemangioma (CH) which developed in adjacent location to a preexisting CH after gamma knife radiosurgery (GKRS). A 36-year-old woman underwent GKRS for a CH in the left lentiform nucleus. Three-and-half years after radiosurgery, MRI revealed a new CH in the left caudate nucleus. Surgical excision of the new lesion was performed. The pathological examination confirmed the diagnosis of CH. In radiosurgery for CH, it should be noted that a new CH may develop, which is likely to result from the interaction between radiation and predisposing factors of the patient.
One-Loop Master Integral for Order-v2n Relativistic Corrections Γ[J/ψ→e+e-]
Jungil Lee,Chaehyun Yu,Hyeon-Kyun Noh 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.2
We show that one-loop scalar integrals contributing to the order-$v^{2n}$ relativistic corrections to the QCD vertex corrections to the spin-triplet $S$-wave heavy-quark-antiquark pair annihilation into a virtual photon can be expressed in terms of a single master integral. With an algebraic reduction combined with the tensor-integral reduction method, we first simplify the scalar integrals as linear combinations of two-point functions. The two-point functions are reduced into a single master integral by using the recurrence relations derived from integration by parts. Order-$v^2$ formulas are explicitly derived, and a strategy to calculate the higher-order relativistic corrections at order $\alpha_s$ is also given. The result may be very useful in calculating the order-$v^{2n}$ relativistic corrections to the leptonic decay width of the spin-triplet $S$-wave heavy quarkonium at order $\alpha_s$.
QCD Radiative Corrections to J/ψ Leptonic Decay by Using the Scalar-Integral Reduction Method
Jungil Lee,Chaehyun Yu 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4
We study the scalar-integral reduction method, which uses the integration-by-parts method, in calculating s corrections to heavy-quarkonium amplitudes. We apply this method to leptonic decay of the spin-triplet S-wave heavy quarkonium as an illustrative example. All possible scalar integrals are reduced into a single master integral in the J=A ! `+`¡ decay at this order. One drawback of this method is that one cannot avoid a mixture of ultraviolet (UV) and infrared (IR) poles during the reduction. We show a way to classify the origin of divergences in loop integrals in the scalar-integral reduction method. We expect this method to be useful in constructing a fast algebraic algorithm for QCD radiative corrections to quarkonium processes.
Wireless Networked Control Systems Using IEEE 802.15.4
Jung-Il Lee,Dong-Hyuk Choi,Dong-Sung Kim 한국지능시스템학회 2006 한국지능시스템학회 학술발표 논문집 Vol.16 No.2
In this paper, a wireless control network based on IEEE 802.15.4 MAC protocol is proposed. The superframe of IEEE 802.15.4 is applied to the proposed wireless control network. The transmission and bandwidth management method are proposed for efficient transmission in the superframe. By these methods, the proposed wireless control network protocol is able to transmit three types of data (periodic data, sporadic data, and non real-time message), and guarantee real-time transmission within deadline.