• 한국광학회지
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• 제17권6호
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• pp.544-547
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• 2006

본 논문에서는 기존의 DBR 격자 기반의 파장선택성 반사기를 대체시킬 수 있는 결합 링 반사기가 집적된 레이저 다이오드를 연산자 분리 시 영역 모델을 통해서 분석한다. 결합 링 반사기는 브래그 격자(Bragg grating) 필요로 하지 않는 평판 도파로 형태의 반사기이다. 결합 링 반사기는 하나의 직선 도파로와 두 개의 결합된 형태의 링 공진기가 하나의 직선 도파로에 결합되어 있다. 위상 조절 전류의 조절에 따른 파장 가변 범위는 수십 nm 정도가 되고, 파장 가변 과정에서 부모드 억압비도 35 dB 이상이 됨을 수치 해석을 통해 확인했다. 또한 결합 링 반사기 레이저 다이오드는 종래의 레이저 다이오드에 비해서 유효 공진기 길이(Effective Cavity Length)가 매우 길기 때문에 진폭 변조 시 20-30 GHz 주파수 영역에서 추가적인 공진 특성을 보이고, 이 특성으로 인해 진폭 변조 대역폭이 상당히 향상될 수 있으리라 기대된다.

• 한국광학회지
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• 제18권1호
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• pp.79-83
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• 2007

본 논문에서는 서로 다른 FSR (free spectral range)을 갖는 두 개의 가변 (tunable) 폴리머 링 공진기 기반의 $1{\times}2$ 스위치를 이용하여 광학적 방식의 채널 선택이 가능한 재구성형 (reconfigurable) 마이크로웨이브 (microwave: MW) 필터를 제안하고 구현하였다. 각 링 공진기는 두 개의 링이 연결되어 있으며 한 개의 링 위에 전극이 형성되어 있으며, 이 전극에 전압을 인가함으로써 열광학효과를 통해 On/Off 스위치로서 동작된다. 입력 MW 신호에 의해서 변조된 광신호를 이 스위치를 통해 특정 포트로 라우팅(routing)하고 광검출기를 통해 복원함으로써 두 개의 채널이 선택되는 MW 대역통과 필터 특성을 얻었다. 중심주파수가 10 GHz인 채널 I 이 선택된 경우, 소멸비는 ${\sim}30dB$, 대역폭은 1 GHz, Q값은 10, 최대 소비전력은 4.1 mW였다. 그리고 중심주파수가 20 GHz인 채널II가 선택된 경우에는 소멸비는 ${\sim}30dB$, 대역폭은 2 GHz, Q값은 10, 최대 소비전력은 8 mW였으며, 각 채널 간의 격리도는 24 dB 이상이었다.

• Bulletin of the Korean Chemical Society
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• 제28권4호
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• pp.520-528
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• 2007

A practical and efficient disposal of PCBs (polychlorinated biphenyls) in waste transformer oil by a chemical dechlorination process has been reported. The transformer oil containing commercial PCB mixtures (Aroclor 1242, 1254 and 1260) was treated by the required amounts of PEG 600 (polyethylene glycol 600), potassium hydroxide (KOH) and aluminum (Al), along with different reaction temperatures and times. The reaction of PEG with PCBs under basic condition produces arylpolyglycols, the products of nucleophilic aromatic substitution. The relative efficiencies of PCB treatment process were assessed in terms of destruction and removal efficiency (DRE, %). Under the experimental conditions of PEG600/KOH/Al/100 oC/2hr, average DRE of PCBs was approximately 78%, showing completely removal of PCBs containing 7-9 chlorines on two rings of biphenyl which appear later than PCB no. 183 (2,2',3,4,4',5',6-heptaCB) in retention time of GC/ECD. However, when increasing the reaction temperature and time to 150 oC and 240 min, average DRE of PCBs including the most toxic PCBs (PCB no. 77, 105, 118, 123 and 169) in PCB family reached 99.99% or better, with the exception of PCB no. 5 and 8 (2,3-diCB and 2,4'-diCB). In studying the reaction of PEG with PCBs, it confirmed that the process led to less chlorinated PCBs through a stepwise process with the successive elimination of chlorines. The process also permits complete recovery of treated transformer oil through simple segregating procedures.

• 청정기술
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• 제14권2호
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• pp.87-94
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• 2008

12-고리를 갖는 큰 기공 제올라이트인 H-모더나이트, H-베타, H-Y상에서 에탄올 아민화반응에 의한 디에틸아민합성반응을 수행하였다. 사용된 큰 기공 제올라이트의 Si/Al 비 증가는 강산점의 감소를 가져왔으며 이 강산점의 세기는 아민으로의 생성 증가와 관련지을 수 있었다. 다차원 채널 형태를 갖는 H-베타, H-Y 제올라이트는 큰 둥지 부피와 낮은 산점세기로 인해 에탄올의 이량화반응에 의한 디에틸에테르의 생성을 촉진하였다. 직선 기공 채널 형태를 갖고 있는 H-모더나이트 제올라이트는 정밀화학 중간체로 널리 쓰이는 모노, 디에틸아민 합성에 적합하였다.

• Animal cells and systems
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• 제12권4호
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• pp.305-311
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• 2008

Age and growth of the mudskipper, Scartelaos gigas were investigated using the second actinost bone of the pectoral girdle, based on an analysis of 560 individuals collected from the mud flats in south west Korea. Specimens were collected semimonthly from March to September of 2003. Actinost and ring radii of each ring group showed a direct one-to-one relationship, with ring radius increasing in tandem with actinost radius. Monthly change in the marginal indices showed that ring formation occurred between May and July(mainly June), being supported by the monthly change in the gonadosomatic(highest in June) and hepatosomatic(lowest in July) indices. Because the species has not been found since November, when air temperature was less than about $10^{\circ}C$, it is thought to enter to hibernation. Therefore, it was suggested that the two new actinost rings may appear a year: one during the spawning season(May-July) and another during hibernation(since November). Although the growth of S. gigas must be limited to short periods each year from March to April and from August to October, its growth rate was considerably fast. The von Bertalanffy growth parameters of S. gigas were $TL_{\infty}$=179.36 mm, K=0.78 $year^{-1}$, $t_0$=-0.7762, and age-length key were $TL_1$=134.3 mm, $TL_2$=158.6 mm, $TL_3$=169.1 mm, $TL_4$=175.0 mm.

• Elastomers and Composites
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• 제44권4호
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• pp.436-441
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• 2009

주사슬에 방향족 고리와 펜타메틸렌 그룹을 포함하고 있는 반유연성 폴리에스터가 direct polycondensation 에 의하여 합성되었다. 합성된 중합체의 구조는 $^1H$-NMR과 FT-IR에 의해, 상전이거동에 대해서는 DSC, TGA 및 직교된 편광현미경에 의하여 관찰되었다. 합성된 중합체의 고유점성도 ($\eta_{inh}$)는 0.46에서 1.30 dL/g 사이의 값으로 측정되었고, 분자사슬 중 강직사슬그룹의 선형성이 클수록 용융전이온도 ($T_m$)는 높았으며, 용해도 조사에 사용된 유기용매에 대한 용해도는 감소되었다. 그리고, 중합체들 중 P-H, P-mH, P-4H는 넓은 비등방성 영역에서 열방성 네마틱 액정상을 나타내었으나 P-R, P-C, P-2B는 액정상을 나타내지 않았다.

• The Korean Journal of Physiology and Pharmacology
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• 제21권6호
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• pp.617-623
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• 2017

The vascular actions and mechanisms of taurine were investigated in the isolated human radial artery (RA). RA rings were suspended in isolated organ baths and tension was recorded isometrically. First, a precontraction was achieved by adding potassium chloride (KCl, 45 mM) or serotonin (5-hydroxytryptamine, 5-HT, $30{\mu}M$) to organ baths. When the precontractions were stable, taurine (20, 40, 80 mM) was added cumulatively. Antagonistic effect of taurine on calcium chloride ($10{\mu}M$ to 10 mM) -induced contractions was investigated. Taurine-induced relaxations were also tested in the presence of the $K^+$ channel inhibitors tetraethylammonium (1 mM), glibenclamide ($10{\mu}M$) and 4-aminopyridine (1 mM). Taurine did not affect the basal tone but inhibited the contraction induced by 5-HT and KCl. Calcium chloride-induced contractions were significantly inhibited in the presence of taurine (20, 40, 80 mM) (p<0.05). The relaxation to taurine was inhibited by tetraethylammonium (p<0.05). However, glibenclamide and 4-aminopyridine did not affect taurine -induced relaxations. Present experiments show that taurine inhibits 5-HT and KCl -induced contractions in RA, and suggest that large conductance $Ca^{2+}$-activated $K^+$ channels may be involved in taurine -induced relaxation of RA.

• 한국수산과학회지
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• 제44권6호
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• pp.695-700
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• 2011

Age, growth, and maturity of Trichiurus lepturus were estimated based on right-handed sagittal otoliths belonging to 1,031 fish collected from January to December 2007 in the East China Sea. The outer margins of the otolith were examined and showed that an opaque zone was formed once per year. Marginal increments in otoliths formed as annual rings between June and August, at the beginning of the spawning season. Fish growth was expressed by the von Bertalanffy growth equation, as follows: $L_t=494.0$ ($1-e^{-0.2453(t+-0.4822)}$) for females and $L_t=330.4$ ($1-e^{-0.4292(t+0.7513)}$) for males, where $L_t$ is the total length in mm and t is age in years. The growth rates of males and females were significantly different (P<0.05).The age composition ranged mostly between ages 2 and 4, and the oldest individuals were 4 years old in males and 6 years old in females. Finally, the age composition of largehead hairtail was compared with data from the 1970s and is discussed in the context of environmental changes.

• 대한인간공학회지
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• 제30권5호
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• pp.659-669
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• 2011

Objective: The aim of this study is to suggest a package layout guideline for low-floor bus by interview with passengers and observations of their behavior. Background: Increasing attention has been introduced the low-floor bus to be more suitable for use by transportation handicapped. Complex issues are involved in providing comfortable services to all people. We are going to suggest package layout guidelines for more comfortable and suitable travel to all people. Method: The two times of survey and video observation sessions were conducted on low-floor buses in Seoul; (1) a finding of potential issues in the first session, (2) a confirming of issues from the last session. Results: The three of major issues were founded in this study; (1) difficulties in supporting body when standing, (2) difficulties in sitting on front wheel pan seat, (3) difficulties in passing through the aisle. Conclusion: There were clear differences between public and transportation handicapped in using some tools which are used for support body such as roof hand rails, side hand rails, and hand rail rings. Some of design problems were founded to improve from the perspective of ergonomics and universal design. Such differences and design guidelines have to be considered in bus design as well as commercial vehicle. Application: The proposed design guidelines can be used to development of low-floor bus and other public transportations.

• 기본간호학회지
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• 제9권2호
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• pp.165-179
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• 2002

Purpose: This descriptive study was done to evaluate the attitude and practice of hand-washing by student nurses. Method: The subjects of the study were 463 senior and junior undergraduate student nurses and RN-BSN students. The questionnaire was developed by the researchers Data were collected from Oct. 16 to Dec. 20. 2001. and analysed by SPSS/WIN. General characteristics. attitude and practice were analyzed by frequency and percentage and differences in attitude and practice according to grade and practice setting were analyzed with $x^2$ test, t-test or ANOVA. Result: 1) The mean frequency of hand-washing was 6.63. Senior students washed more frequently than junior students. 2) The reasons for non-compliance were 'not being accustomed', 'forgetting', and 'not accessible'. 3) The mean time for hand-washing was 23.79 sec., less than the stated appropriate time of 42 18 sec. 4) 90% of the students washed their hands 'after contacting excretions and contaminated items' and few washed 'before giving care to the client'. 5) Most students washed hands rotationally rubbing with soap and water. 6) While washing, they removed their rings more often than their watches. 7) Soap bar (52.8%) and paper towel (69.6%) were most frequently used as decontaminating agent and drying method, but detergent solution (74.2%) and paper towels (60%) were considered as the most appropriate agent and method. 8) Hand-washing was perceived important generally 'to protect from cross-infection'. 'to protect one-self' and 'the most cost effective'. 9) All students responded nurses should practice 'hand-washing.'