• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.29-35
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• 2016

It is important to uniformly supply the fuel gas into the reaction activity area in polymer electrolyte membrane fuel cell (PEMFC). Recent studies have shown that the cell performance can be significantly improved by employing metal foam gas distributor as compared with the conventional bipolar plate types. The metal foam gas distributor has been reported to be more efficient to fuel transport. In this study, three-dimensional computational fluid dynamics (CFD) simulations have been performed to examine the effects of metal foam flow field design on the fuel supply to the reaction site. Darcy's law is used for the flow in the porous media. By solving additional advection equation for fluid particle trajectory, the gas transport has been visualized and examined for various geometrical configuration of metal foam gas distributor.

• Nuclear Engineering and Technology
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• 제49권3호
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• pp.466-475
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• 2017

Coolant mixing under natural circulation flow regime constitutes a key parameter that may play a role in the course of an accidental transient in a nuclear pressurized water reactor. This issue has motivated some experimental investigations carried out within the OECD/NEA PKL projects. The aim was to assess the coolant mixing phenomenon in the reactor pressure vessel downcomer and the core lower plenum under several asymmetric steady and unsteady flow conditions, and to provide experimental data for code validations. Former studies addressed the mixing phenomenon using, on the one hand, one-dimensional computational approaches with cross flows that are not fully validated under transient conditions and, on the other hand, expensive computational fluid dynamic tools that are not always justified for large-scale macroscopic phenomena. In the current framework, an unsteady coolant mixing experiment carried out in the Rossendorf coolant mixing test facility is simulated using the three-dimensional porous media capabilities of the thermal-hydraulic system CATHARE code. The current study allows highlighting the current capabilities of these codes and their suitability for reproducing the main phenomena occurring during asymmetric transient natural circulation mixing conditions.

• 분석과학
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• 제35권5호
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• pp.218-227
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• 2022

A simple and fast throughput flow injection (FI) system with a merging-zone technique was designed to determine ferrous and ferric in an aqueous solution. The method is based on the direct reaction of ferrous with a Bathophenanthroline reagent (Bphen) in acidic media. The forming red complex absorbs light at 533 nm. All conditions of the flow injection system were investigated. The analytical curve of ferrous was linear in the range of 0.07 to 4 mg/L with an r² value of 0.9968. The detection and quantification limits were 0.02 and 0.04 mg/L, respectively. The molar absorptivity and Sandell's sensitivity were 4.0577 × 10⁶ L/mol cm and 25 × 10^-5 ㎍/cm², respectively. The homemade valve was low-cost with high repeatability (n = 7) at an RSD of 1.26 % and zero dead volume. The values of the dispersion coefficient were 2.318, 2.022, and 1.636 for the concentrations of 0.2, 1, and 3 mg/L, respectively. The analysis throughput of the designed flow injection unit was 57 sample per hour.

• Journal of Microbiology and Biotechnology
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• 제3권4호
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• pp.292-297
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• 1993

Aspergillus niger No. PFST-38 was grown on complex media in 30L agitated fermentors at various aeration rates and stirrer speeds. We could correlate the mixing time as a function of the Reynolds number and the apparent viscosity, as follows. ${\theta}_M=2.95\;\NRe^{-0.52},\;{\theta}_M=1.88\;{\eta_a}^{0.57}$ Also, the effects of the apparent viscosity (${\theta}_a$), the impeller rotational speed (N), the air flow rate ($V_s$), and the mixing time (${\theta}_M$) on the oxygen transfer coefficient, $K_L a$ were determined experimentally, and equated as follows. $K_La=12.04N^{0.88}Vs^{0.71}{n_a}^{-0.83},\;K_La=30.2N^{0.88}Vs^{0.71}{\theta_M}^{-1.45}$ $K_La$ increased as the agitation speed and the air flow rate increased. The rate of $K_La$ increase was dependent more on the rotational speed of impeller than on the air flow rate. The glucoamylase production increased with the increase of the agitation speed upto at 500 rpm and increased with the increase of air flow rate upto at 1.0 vvm. The values calculated from the above equation confirmed that the experimental maximum production of glucoamylase was achieved when the $K_La$ and the apparent viscosity of the broth were $260\;hr^{-1}$ and 1800 cps, respectively.

• 만화애니메이션 연구
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• 통권38호
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• pp.29-51
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• 2015

초고속 인터넷 망과 모바일 디바이스의 발달, 그리고 그를 통한 소셜 네트워크의 확산으로 대중 미디어 생태계는 생산자가 소비자에게 콘텐츠를 제공하는 일방성에서 벗어나 소비자가 직접 콘텐츠를 생산하고 소비하는 미디어 프로슈머 문화로 확대되고 있다. 그러한 시대적 경향에 더불어 유튜브를 위시한 다양한 동영상 공유 플랫폼은 콘텐츠 생산자에게 광고수익을 배분하는 방식으로 콘텐츠 프로슈머들과 윈-윈(win-win)하는 모델의 플랫폼을 제공함으로써 개인의 동영상 콘텐츠 배급 채널이 수천만 명의 구독자를 확보하고 연간 100억 원 이상의 수익을 얻는 등 콘텐츠 산업에 일대 변혁이 일어나고 있다. 본 논문은 꾸준한 성장세를 보이고 있는 동영상 배급 채널과 숏폼 미디어 콘텐츠들 그리고 숏폼 미디어에서의 애니메이션 콘텐츠의 특성들을 다각도로 분석하여 온라인 동영상 미디어 플랫폼의 시대에 애니메이션 콘텐츠가 뻗어나갈 수 있는 새로운 시장을 모색하고자한다. 나아가 기존 애니메이션 콘텐츠와 구별되는 숏폼 미디어에서의 애니메이션 콘텐츠의 특징적 요소들과 성공사례를 제시함으로써 1인 창작자 또는 소규모 팀 애니메이션 창작자들에게 창작 애니메이션을 통한 자생의 방향성을 제시하는데 본 연구의 목적이 있다.

• 대한환경공학회지
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• 제35권6호
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• pp.449-455
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• 2013

소규모 하수처리시스템에 다양한 반송비와 고정식 담체를 적용하여 합성폐수에서 질소, 인의 제거를 검토하였다. 담체를 첨가 시 질소의 제거율은 40.1%에서 65.1%로 증가하였으나 COD와 인의 제거에는 영향이 없었다(<5%). 반송을 통해 유량을 2배(2Q)로 증가시킨 경우 질소의 제거율은 7% 정도가 증가하였으나, 인 제거율은 반송비가 증가됨에 따라 31.8에서 26.6%로 감소하였다. 무산소조에서 담체에 부착된 미생물은 약 73.4 $mg/cm^2$로 존재하였으며, FISH분석 결과 탈질 미생물인 Pseudomonas aeruginosa 존재 (약 58%)를 확인하였다.

• 한국산업보건학회지
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• 제24권2호
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• pp.201-207
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• 2014

Objectives: Flow rate stability is very important for obtaining reliable measurements. However there is no easily used method for checking whether the flow rate set at the initial stage is sustained during sampling. The purpose of this study was to develop a method to evaluate the flow rate performance of gas sampling pumps with adsorbents commonly used to sample gases. Materials and methods: We tested the back pressure of gas sampling pumps commonly used in Korea with adsorbents such as charcoal and silica tubes and attempted to discover the combination conditions of adsorbents in accordance with back pressure required by ISO standard 13137. Results: We found the combination of sampling adsorbents to be applicable to the pressure drop required by the ISO standard for evaluating flow rate stability under increasing pressure drop and long term (eight-hour) performance. Conclusions: This evaluation method of using a sampling media matrix for checking flow rate stability as proposed by this study could be a highly useful tool for determining the reliability of the performance pumps before sampling.

• Asian Journal of Atmospheric Environment
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• 제11권2호
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• pp.107-113
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• 2017

This study describes (1) the impact of positive sampling artifacts caused by not only a filter-based sampling, but also a denuder-based sampling in the determination of particle-phase organic carbon (POC), (2) the effect of sample flow rate on positive artifacts, and (3) an optimum flow rate that provides a minimized negative sampling artifact for the denuder-based sampling method. To achieve the goals of this study, four different sampling media combinations were employed: (1) Quartz filter-alone (Q-alone), (2) quartz filter behind quartz-fiber filter (QBQ), (3) quartz filter and quartz filter behind Teflon filter (Q-QBT), and (4) quartz filter behind carbon-based denuder (Denuder-Q). The measurement of ambient POC was carried out in an urban area. In addition, to determine gas-phase OC (GOC) removal efficiency of the denuder, a Teflon filter and a quartz filter were deployed upstream and downstream of the denuder, respectively with varying sample flow rates: 5, 10, 20, and 30 LPM. It was found that Q-alone sampling configuration showed a higher POC than QBQ, Q-QBT, and Denuder-Q by 12%, 28%, and 23%, respectively at a sample flow rate of 20 LPM due to no correction for positive artifact caused by adsorption of GOC onto the filter. A lower quantity of GOC was collected from the backup quartz filter on QBQ than that from Q-QBT. This was because GOC was not in equilibrium with that adsorbed on the front quartz filter of QBQ during the sampling period. It is observed that the loss of particle number and mass across the denuder increases with decreasing sample flow rate. The contribution o f positive arti facts to POC decreased with increasing sample flow rate, showing 29%, 25%, and 22% for 10, 20, and 30 LPM, respectively. The 20 LPM turns out to be the optimum sample flow rate for both filter and denuder-based POC sampling.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 추계 학술대회 논문집
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• pp.134-142
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• 2005

지하매질에서 핵종이동현상을 가시적으로 관찰할 수 있는 실험실규모 실험장치를 개발하여 이동실험을 수행하였다. 이 실험장치는 $50{\times}50cm$ 규모 화강암과 아크릴상층부로 구성되어있다. 실험에는 삼중수소, 음이온, 수착성양이온 뿐만 아니라 이동경로를 관찰할 수 있는 유기염료도 포함하였다. 시간에 따른 물질이동양태를 사진을 찍어 컴퓨터에 저장하였다. 또. 이동과정을 모사하고 단위공정별로 분석해 볼 수 잇는 이동모델도 개발하였다. 컴퓨터모사를 통해 균열내 흐름장에서 압력과 유속분포를 계산하고, 균열내 이동양태와 유출곡선을 계산해 실험결과와 비교 평가하였다.

• 한국게임학회 논문지
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• 제17권2호
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• pp.165-174
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• 2017

본 연구는 건강 기능성 게임인 흡연시뮬레이션 게임의 몰입을 결정하는 요인에 대해 파악하고 이들 요인들이 몰입에 어떠한 영향을 미치는지 분석하였다. 특히 게임 중에 발생하는 뇌 활동 패턴이 게임몰입과 어떠한 상관관계를 가지는지 뇌파측정과 몰입과의 관계를 규명하고자 하였다. 이를 위해 게임몰입의 정도를 종속변인으로 설정하고 몰입에 영향을 미칠 수 있는 감정이입, 건강관심도, 생리적 지표인 뇌파(${\alpha},{\beta}$)를 독립변인으로 설정하여 회귀분석을 실시하였다. 연구결과 흡연시뮬레이션 게임에서 몰입에 감정이입, 건강관심도, ${\beta}$파는 정적으로 영향을 미치고 있었으며, ${\alpha}$파의 경우 부적으로 영향을 미치고 있음이 확인되었다. 본 연구는 기능성 게임몰입에 영향을 미칠 수 있는 사용자 경험과 신경생리학적 변화에 대하여 자기 보고와 더불어 뇌파측정을 통해 실증적으로 분석하고 게임몰입의 결정요인을 규명하고 있다는 점에서 이론적 의미가 있다.