• 한국유체기계학회 논문집
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• 제15권5호
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• pp.11-19
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• 2012

The main function of fuel cell manifold is to render reactants distribution as uniform as possible into a fuel cell stack. The purpose of this study is to numerically investigate the effects of stack manifold design on reactants distribution within a fuel cell stack. Four manifold designs with different manifold entrance shapes (expansion or diffuser) and different values of the extra width between the cell outer channel and manifold side wall are considered and applied to the fuel cell stack consisting of 50 cells. Since the fuel cell stack geometry involves several millions of grid points for numerical calculations, a parallel computing methodology is employed to substantially reduce the computational time and overcome the memory requirement. The numerical simulations are carried out and calculated results clearly demonstrate that both the manifold entrance shape and extra width have a substantial influence on manifold performance, controlling the degree of flow separation and entrance length for fully developed flow in the manifold channel. Finally, we suggest the optimum design of fuel cell manifold based on the simulation results.

• 기본간호학회지
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• 제9권3호
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• pp.473-483
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• 2002

The purpose of this study was to explore the attitude of student nurses to euthanasia. The convenient sample for this study consisted of 293 nursing students at a nursing college in Kyeongi Province. The data were collected from Oct. 15, 2002 to Oct. 30, 2002 and were analyzed using frequency, percentage, and $X^2$-test with the SAS package. The results of this study are as follow : 77.1% of students agreed to passive euthanasia and 70.6% subjects agreed to legalization of passive euthanasia. 78.5% of students can given an exact explanation of the concept of hospice. They obtained information about hospice from the mass media (1.1%), books (30.0%), friends and neighbors (3.4%), and religious groups (2.4%). The preferred place for death was reported to be home (75.4%), hospital (9.4%) or a peaceful place (6.3%). Fears of facing death were suffering in death (23.4%), grief of remaining family (21.2%), unknown about the other world (10.0%), separation from people who are loved (9.7%), forgotten from the people's memory(6.3%). In conclusion, the attitude of student nurses toward passive euthanasia approached a positive direction. But euthanasia was seen as dangerous and having multiple problems. Therefore the training for student nurses as health professionals should include content on dealing with hospice care and euthanasia.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1137-1142
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• 2004

A spectrophotometric and first derivative spectrophotometric method was developed in aquatic Tween 80 micellar solutions for selective determination of nickel without using any pre-separation step. 1-(2-Pyridylazo)-2-naphthol (PAN), as a sensitive chromogenic complexing agent formed a red-colored Ni(II)-PAN complex in Tween 80 media with satisfactory solubility and stability. Conditions such as pH, PAN concentration, type and concentration of micellizing agent were optimized. Molar absorptivity of Ni-PAN complex was found $4.62\;{\times}\;10^4L\;cm^{?1}\;mol^{?1}$ at 569 nm, under the optimum condition. Calibration graphs were derived by zero, first and second derivative spectrophotometry at maximum wavelengths of 569, 578 and 571 nm with linear ranges of 30-1800, 20-2500 and 30-2000 ng $mL^{?1}$ , respectively. Precision as standard deviation as well as accuracy as recovery percent were in the range of 1-20 ng $mL^{?1}$, and 93.3-103.3%, respectively, for the entire of the linear ranges. Spectrophotometric detection limit was 3 ng $mL^{?1}$ and effects of diverse ions on the first derivative determination of nickel were studied to investigate selectivity of the method. Interferences of cobalt and copper on the nickel determination were prevented using o-phenanthroline as masking agent. The recommended procedures were applied to the various synthetic and stainless steel alloys, tea leaves and human hair, with satisfactory results.

• Bulletin of the Korean Chemical Society
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• 제24권1호
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• pp.27-31
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• 2003

A Polythiophene-quinoline/glassy carbon (PTQ/GC) modified electrode was developed for the determination of trace mercury in industrial waste water, natural water, soil, and other media. The electrode was prepared by the cyclic voltammetric polymerization of thiophene and quinoline on glassy carbon (GC) electrode by the potential application from -0.6 V to +2.0 V (50 mV/sec) in a solution of 0.1 M thiophene, quinoline and tetrabutyl ammonium perchlorate (TBAP) in acetonitrile. Optimum thickness of the polymer membrane on the GC electrode was obtained with 20 repeated potential cyclings. The redox behavior of Cu(Ⅱ) and Hg(Ⅱ) were almost identical on this electrode. The addition of 4-(2-pyridylazo)resorcinol (PAR) to the solution containing Cu(Ⅱ) and Hg(Ⅱ) allowed the separation of the components due to the formation of the Cu(Ⅱ)-PAR complex reduced at -0.8V, which was different from the Hg(Ⅱ) reduced at -0.5 V on a saturated calomel electrode (SCE). The calibration graph of Hg(Ⅱ) shows good linear relationship with the correlation factor of 0.9995 and the concentration gradient of 0.33 ㎂/㎠/ppb down to 0.4 ppb Hg. The method developed was successfully applied to the determination of mercury in samples such as river, waste water, and sea water.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2015년도 추계학술대회
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• pp.43-44
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• 2015

LTE-Advanced system has been deployed with 2 and 4 transmission antennas (Tx) while the specification supports up to 8Tx. Due to deployment space, antenna dimension and complexity, the needs of deploying 8Tx system has not been motivated by operators. Recently, three dimensional (3D) beamforming with active antenna has attracted significant attention in the wireless industry. By incorporating 2D active array into LTE-A systems, the system offers freedom in controlling radiation on elevation and horizontal dimension. When the number of antennas increases in the form of 2D arrangement, spatial separation can be realized simultaneously in horizontal and elevation domain and vertical beam-steering can increase SINR of UEs in high floors. In this paper, we study the system operations and implementations for supporting 3D beamforming with 8Tx antennas. In our schemes, by reusing the conventional CSI feedback framework, the system can operate 2D active array without harming the backward compatibility. Evaluation results show that 3D beamforming provides capacity boosting over the conventional 2D beamforming systems while keeping same antenna structure.

• 디지털융복합연구
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• 제11권10호
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• pp.453-458
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• 2013

HMM 음성 인식 시스템은 환경적 잡음과 여러 음성의 혼합으로 인하여 정확한 음성을 인지하지 못하는 단점이 있다. 따라서 본 논문은 잡음 음성으로 부터 원하는 음성만 선택하여 추출하기 위한 음성 특징 추출 기법을 CHMM을 이용하여 제안한다. 선택적 음성 추출을 위한 채널 유사성 상관 관계를 이용하여 음성 특징을 추출하는 방법을 사용하였다. 제안 기법의 실험 평가한 결과 평균 분리 왜곡도가 0.430dB 감소됨을 보임으로써 제안한 방법의 우수성을 확인하였다.

• Macromolecular Research
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• 제12권3호
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• pp.269-275
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• 2004

To graft N-isopropylacrylamide (NIPAAm) onto alginate, varying dosages of ${\gamma}$-rays were irradiated onto alginate films in deionized water and methanol media, which are non-solvents of alginate. We investigated the hydrogels graft ratio, mechanical strength, swelling kinetics and ratio, and behavior with respect to drug release. The graft yield of NIPAAm increased upon increasing the irradiation dose. The use of the aqueous solution increased the graft yield relative to that obtained in methanol. The mechanical strength of the grafted hydrogels increased after grafting with NIPAAm. In a study of the swelling kinetics, we found that all hydrogels reached an equilibrium swollen state within 3 h. The equilibrium swelling ratio of the hydrogels decreased upon increasing the irradiation dose. The swelling ratio of the hydrogels decreased dramatically between 30 and 35$^{\circ}C$ because phase separation of NIPAAm occurred at 32$^{\circ}C$. The swelling process, with respect to the temperature change, was repeatable. An NIPAAm-grafted alginate containing a drug sustained its release rate until 3 h after an initial high drug release caused by a burst effect.

• 디자인학연구
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• 제17권2호
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• pp.147-156
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• 2004

기업은 국민경제를 구성하는 기본적 단위이며, 생산수단의 소유와 노동의 분리를 기초로 하여 영리목적을 추구하는 독립적인 생산경제단위를 이루고 있다. 시장경제 메커니즘에서 생존하기 위해 계획경제에 의해 가격과 생산량이 결정되었다 하더라도 소비자의 기호에 따라 생산량과 수요량은 일치할 수 없게 되었다. 기업은 소비자의 기호를 파악하여 상품개발을 하고 광고를 위해 소비자에게 자신의 글 그림 음성 등 시청 각 매체가 동원된다. 광고란 광고 메시지 속에 어떤 형태로든 밝혀져 있는 기업이나 비영리기관 또는 개인이 여러 매체를 통한 커뮤니케이션이다. 기업은 상품만을 알리는 것이 아닌 기업자체가 판매원이 되어서 기업의 이미지를 소비자에게 어필하는 시대가 되었다. 기업 아이덴티티는 기업이 표방하고자하는 내용을 시각화하고 그 기업이 가진 모토나 슬로건 등 기업의 문화를 형상화하여 소비자에게 상품과 기업의 신뢰를 구축하여 지속적인 고객으로 유지하도록 마케팅전략을 세우고 있으며 90년대 www의 발전으로 매체가 online으로 확대되었다. www의 발전은 세계를 하나의 네트워크로 묶어주고 있으며 제한된 공간에서 무한 경쟁의 시장으로 변하게 되었다. 본 연구에서는 웹 아이덴티티의 개념과 특성을 정의하고 스포츠 신발을 중심으로 스포츠신발 사이트의 아이덴티티의 표현을 조사 분석한다. 세계적 다국적 기업이 제공하는 한국어 판 웹 아이덴티티와 국내기업이 제공하는 웹 아이덴티티가 과연 국내 소비자에게 어떤 영향을 미치고 있는가에 대해 연구하였다. 설문조사는 20대를 중심으로 404명을 조사하였고 전문통계 프로그램인 SAS v8.0을 통해 통계분석을 하였다. 설문조사의 통계분석을 통해 인터넷으로 대학생들의 인터넷 이용실태를 알 수 있었으며 나이키, 아디다스, 리복, 프로스펙스의 웹 아이덴티티를 분석함으로 현재 웹 아이덴티티의 효과를 분석하였다. 또한 사이트 방문에 따른 메이커 선호도에 따른 웹 아이덴티티의 운영에 대해 연구하였다.

• 대한환경공학회지
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• 제29권4호
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• pp.452-459
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• 2007

부유 및 부착성장 미생물을 이용한 접촉안정형 영양염류처리 하이브리드공정은 질산화 반응조내에 EPS(Expanded Poly-Styrene) 여재를 충진하여 autotrophs와 heterotrophs의 분리성장과 질산화균의 우점화를 도모함으로써 수리학적체류시간 6시간 이내에서도 양호한 처리수질을 얻을 수 있는 공정이다. 본 공정의 운전결과 방류수의 $BOD_5,\;COD_{Mn}$, SS의 평균농도는 5.2 mg/L, 7.3 mg/L, 4.9 mg/L이었으며, T-N 및 T-P농도는 6.8 mg/L 및 0.6 mg/L로서 양호한 처리 결과를 얻을 수 있었다. 또한 본 공법의 평균 제거효율은 $BOD_5,\;COD_{Mn}$, SS의 경우 94.6%, 79.8%, 94.9%이었으며, T-N 및 T-P로서 70.8% 및 76.9%로 나타났다. EPS 여재에 부착된 부착미생물 군집의 16S-rRNA 분석결과 ammonia-oxidizing bacteria로 알려진 Nitrosomonas속, Nitrosoccus속, Gallionella속이 포함된 cluster가 EPS 여재에 부착된 biofilm의 6% 정도인 것으로 조사되었다. 결과적으로 질산화미생물의 우점화를 통해 질산화 반응시간을 단축시킴으로서 6시간 이내의 짧은 수리학적 체류시간에서도 T-N 및 T-P농도를 10 mg/L 및 1.0 mg/L 이하로 처리할 수 있었던 것으로 사료된다.

• 한국수정란이식학회지
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• 제15권1호
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• pp.67-75
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• 2000

This study was conducted to establish the optimal conditions for in vitro embryo production using oocytes derived from follicles of slaughter-house ovaries. The ovaries of Hanwoo were obtained from a local slaughter-house. The oocytes were aspirated from visible follicles of 2~7mm in diameter. The recovered oocytes which were completely surrounded by at least 2 layers of cumulus cells and a homogeneous cytoplasmic pigmentation were used. The selected oocytes were washed 3 or 4 times with D-PBS containing 10% bovine calf serum (BCS) and matured in vitor (IVM) in Ham's F-10 supplemented with 10% BCS or 0.01 $\mu\textrm{g}$/ml epidermal growth factor(EGF) at 39$^{\circ}C$ under 5% CO2 in air for 24 hours. They were fertilizqed in vitro (IVF) with fresh sperm separated by Percoll density gradient or swim-up in TALP media. The zygotes were cultrued with or without bovine oviductal epitherial cells(BOEC) in media(HECM-6 supplemented with 11 amino acid and / or TCM-199 supplemented with 10% BCS) for 7 to 10 days. The results obtained were as follow: The cleavage rate and developmental rate to blastocyst after maturation and IVF were not significantly different between Ham's F-10 with EGF(76.0% vs. 44.0%) and BCS(75.9% vs. 43.6%)(P<0.05). The cleavage rate and development rate to blastocyst after fertilizing by swim-up or Percoll method were not signifciantly(P<0.05) different between swim-up (80.2% vs. 29.2%) and Percoll(81.9% vs. 26.5%) (P<0.05). The cleavage rate in TCM 199(80.5) was signficiantly higher than that in HECM-6 (72.0%) (P<0.05). However, developmental rate to blastocyst using TCM 199 following HECM-6 for 3 or 4 days (42.2%) was significantly higher than that in TCM-199 alone(26.7%)(P<0.05). The cleavage rate and development rate of embryos produced in vitro by exchange timing for HECM-6 media were not significantly different between in day 3(78.6% vs. 45.5%) and day 4(75.0% vs. 43.2%)(P<0.05). The cleavage rate and developmental rate to blastocysts according to co-culture system were not significantly different between with (74.2% vs. 41.4%) and without BOEC(73.95 vs. 43.5%) (P<0.05). The number of blastomere in blastocyst stage after co-culture with or without BOEC was not significantly different (106.7$\pm$5.1 and 96.6$\pm$4.0). In conclusion, the most transferable IVP embryos could be produced from Ham's F-10 medium for IVM, Percoll density gradient method for IVF sperm separation and in vitro culture in HECM-6 until day 3 or day 4, and then transferred into TCM-199 until day 9 within adequate embryo density in culture droplets after insemination.