• Carbon letters
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• 제14권1호
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• pp.40-44
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• 2013

The bipolar plate is the most important and most costly component of proton exchange membrane fuel cells. The development of a suitable low density bipolar plate is scientifically and technically challenging due to the need to maintain high electrical conductivity and mechanical properties. Here, bipolar plates were developed from different particle sizes of natural and expanded graphite with phenolic resin as a polymeric matrix. It was observed that the particle size of the reinforcement significantly influences the mechanical and electrical properties of a composite bipolar plate. The composite bipolar plate based on expanded graphite gives the desired mechanical and electrical properties as per the US Department of Energy target, with a bulk density of 1.55 $g.cm^{-3}$ as compared to that of ~1.87 $g.cm^{-3}$ for a composite plate based on natural graphite (NG). Although the bulk density of the expanded-graphite-based composite plate is ~20% less than that of the NG-based plate, the I-V performance of the expanded graphite plate is superior to that of the NG plate as a consequence of the higher conductivity. The expanded graphite plate can thus be used as an electromagnetic interference shielding material.

• 생물정신의학
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• 제18권4호
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• pp.217-224
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• 2011

Subsyndromal bipolar symptoms are common during maintenance treatment and appear to be associated with relapse into an episode of the same polarity. This implies subsyndromal symptoms are an important problem in recurrent bipolar disorder and require more additive and infallible therapeutic intervention. Undetected, untreated subsyndromal states lead patients to have poor prognosis and quality of life. The combination of a long undetected illness and significant psychosocial impairment renders early identification and intervention vital for the treatment of bipolar disorders. Methods for early identification includes finding prodromes, using screening tools such as the HCL-32 (Hypomania Checklist-32) and the BSDS (bipolar spectrum diagnostic scale). Various augmentation treatment methods would be needed to reduce subsyndromal symptoms, especially, psychosocial treatment has the potential to help patients address the multiple psychosocial problems associated with this chronic illness. To overcome difficulties of diagnosing subsyndromal disorder and to treat it appropriately, a staging system was suggested by some researchers. It assumes that earlier stages have better prognosis and require simpler therapeutic regimens. Staging may assist in treatment planning and prognosis of bipolar disorder, and emphasize the importance of early intervention. Further research is required in this exciting and novel area.

• Corrosion Science and Technology
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• 제12권4호
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• pp.171-178
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• 2013

In a polymer membrane fuel cell stack, the bipolar plate is a key element because it accounts for over 50% of total costs of the stack. In order to lower the cost of bipolar plates, 316L stainless steels coated with nitrides such as TiN and CrN by physical vapor deposition were investigated as alternative materials for the replacement of traditional brittle graphite bipolar-plates. For this purpose, interfacial contact resistances were measured and electrochemical corrosion tests were conducted. The results showed that although both TiN and CrN coatings decreased the interfacial contact resistances to less than $10m{\Omega}{\cdot}cm^2$, they did not significantly improve the corrosion resistance in simulated polymer electrolyte membrane fuel cell environments. A CrN coating on 316L stainless steel showed better corrosion resistance than a TiN coating did, indicating the possibility of using modified CrN coated metallic bipolar plates to replace graphite bipolar plates.

• Nonlinear Functional Analysis and Applications
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• 제28권1호
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• pp.295-309
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• 2023

In this paper, we introduce the notion of α-Geraghty contractive type covariant and contravariant mappings in the bipolar metric spaces. In addition, we prove some fixed point theorems, which give existence and uniqueness of fixed point, for α-Geraghty contractive type covariant and contravariant mappings in complete bipolar metric spaces. Finally, we show some examples to support our main results.

• 정신신체의학
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• 제18권1호
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• pp.19-29
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• 2010

연구목적 : 본 연구를 통해 양극성 장애 I형 혹은 II형 진단 기준에는 부합하지 않지만, (경)조증적 성향 혹은 기분 불안정성 등의 양극성 경향(bipolar tendency, bipolarity)을 가진 사람에게서, 주관적으로 지각하는 스트레스 수준, 스트레스 취약성을 반영하는 것으로 알려진 A형 행동 유형(Type A Behavior Pattern, TABP), 그리고 건강하지 못한 생활습관의 위험이 증가되어 있는지 확인하고자 한다. 방 법 : 정신과적 병력이 없는 30세 이상의 1987명의 연구 대상군이 분석에 포함되었다. 이들 중에서 기분장애설문지 (Mood Disorder Questionnaire, MDQ)의 (경)조증적 증상 경험에 대한 13개 항목 중에서 7개 항목에 "예"라고 응답한 사람들을 양극성 경향군으로 분류하였다. 양극성 경향군과 비양극성 경향군 사이에서 지각된 스트레스 척도(Perceived stress scale, PSS), TABP를 반영하는 A/B 생활 습관 설문(A/B Lifestyle ques-tionnaire) 점수와, 음주, 흡연, 불규칙적인 식사, 운동 부족 등의 생활 습관 변인을 비교하였다. 결 과 : 양극성 경향군(329명, 16.6%)은 비양극성 경향군에 비해 TABP를 반영하는 A/B 생활 습관 설문의 총 점수가 유의미하게 높았으며(125.4점 vs. 115.9점, p<0.001), TABP로 판정(총 점수 135점 이상)된 비율도 양극성 경향군에서 유의미하게 높은 것으로 관찰되었다(41.3% vs. 30.1%, p<0.001). 주관적으로 지각하는 스트레스 수준의 비교에서도, 양극성 경향군이 비양극성 경향군에 비해 유의미하게 높았다(18.5 vs. 16.5, p<0.001). 생활습관의 비교에서 '불규칙적인 식사'(20.1% vs. 14.3%, p=0.002), '주 4회 이상 음주'(29.8% vs. 16.5%, p<0.001), '현재 흡연'(41.9% vs. 23.0%, p<0.001), '주 2회 이하 운동'(63.2% vs. 55.1%, p=0.007) 이라고 응답한 사람의 비율이 양극성 경향군에서 유의미하게 높았다. 결 론 : 양극성 경향을 가진 경우는 스트레스에 취약한 행동 양상이 높게 관찰되고, 주관적으로 지각하는 스트레스 수준도 높고 흡연, 음주, 불규칙한 식사와 운동 부족과 같은 건강하지 못한 생활 습관을 가지고 있을 위험도 높은 것으로 확인되었다. 이러한 위험 요소들은 비만, 대사증후군, 당뇨, 그리고 심혈관계 질환의 발병 위험을 높일 수 있으므로, 양극성 경향을 가진 사람들은 스트레스 관리 및 건강한 생활 습관을 유지하기 위한 보다 적극적인 노력이 필요하다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.352-355
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• 2006

As the stainless steel has good corrosion resistance, mechanical property and ease of manufacture, it has been studied as the candidate material of metallic bipolar plate for automotive PIMFC. But, metal is dissolved under fuel cell operating conditions Dissolved ions contaminate a membrane electrode assembly (MEA) and, decrease the fuel cell performance. In addition, metal oxide formation on the surface of stainless steel increases the contact resistance in the fuel cell. These problems have been acted as an obstacle in the application of stainless steel to bipolar plate. Therefore, many kinds of coating technologies have been examined in order to solve these problems. In this study, stainless steel was coated in order to achieve high conductivity and corrosion resistance by several methods. Contact resistance was measured by using a tensile tester and impedance analyzer Corrosion characteristics of coated stainless steel were examined by Tafel-extrapolation method from the polarization curves in a solution simulating the anodic and cathodic environment of PEMFC. Fuel cell performance was also evaluated by single cell test. We tested various coated metal bipolar plate and conventional and graphite were also tested as comparative samples. In the result, coated stainless steel bipolar plate exhibited better cell performance than graphite to bipolar plate.

• 상하수도학회지
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• 제26권3호
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• pp.409-421
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• 2012

Ethanolamine (ETA) is mainly used to prevent corrosion of pipe in secondary cooling system of nuclear power plant. Condensed ETA in wastewater could increase COD and T-N when it was emitted to natural water system. Compared to conventional treatments, electrochemical oxidation process using packed bed bipolar electrodes was adopted to treat COD and T-N. According to arrangement of feeder electrode, single packed bed bipolar electrode reactor and multi-paired packed bed bipolar reactor were developed and conventional zero-valent iron (ZVI) was selected as conducting bipolar electrode. Bipolar electrodes were coordinated three-dimensionally in the reactor. The experimental results showed that COD and T-N was little removed in unit system at different pH condition (pH 8 and 11) on 100V. However, in multi-paired system that applied 600V, COD was eliminated 80.85% (anode-cathode-anode, A-C-A) and 85.11% (cathode-anode-cathode, C-A-C), respectively. T-N was also removed 96.88% (A-C-A) and 90.63% (C-A-C), simultaneously. Current efficiency was estimated both single and multi-paired system. At unit bipolar packed bed reactor, current efficiency was almost zero, however in multi-paired system, current efficiency was 300~500% at A-C-A and 250~350% at C-A-C. Current efficiency was over 100% hence it was confirmed that this system is more effective than conventional electrochemical oxidation system.

• 생물정신의학
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• 제16권3호
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• pp.205-211
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• 2009

Objectives : Serum and plasma BDNF levels have been shown to be decreased in patients with mood disorder such as major depressive disorder and bipolar disorder. We investigated whether platelet BDNF levels would be lower in patients with acute bipolar manic episode compared with those of normal controls. Methods : BDNF levels were examined in platelet-rich plasma(PRP) and platelet-poor plasma(PPP) in 20 healthy controls and 20 hospitalized patients who were diagnosed as bipolar I disorder, most recent episode manic using a Structured Clinical Interview for DSM-IV. And severity of manic symptoms was measured using Young Mania Rating Scale(YMRS). Platelet BDNF level was calculated by subtracting PPP BDNF from PRP BDNF level, and dividing the result by the total platelet count, and it was expressed as pg/$10^6$ platelet. Results : Platelet BDNF levels were significantly lower in patients with acute bipolar manic episode(4.55${\pm}$3.36pg/$10^6$ platelet) than in normal controls(6.84${\pm}$2.32pg/$10^6$ platelet)(p=0.008). However we failed to reveal the significant negative correlation between platelet BDNF levels and YMRS scores in patients with acute bipolar episode. Conclusion : Our finding suggests that there is a decrease in the platelet BDNF of patients with acute bipolar manic episode.

• 생물정신의학
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• 제9권2호
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• pp.129-139
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• 2002

Objective:This study was performed to investigate the prescribing patterns of antimanic agents in the treatment of acute bipolar disorder inpatients in Korea from 1990 through 2000. The results will serve as the basic data for the practice guideline for the pharmacotherapy of bipolar disorder patients in Korea. Method:Retrospective chart review of bipolar disorder inpatients of Soonchunhyang Medical Center in Seoul and Chun-An was conducted for each of the year 1990, 1995, and 2000. The following data are collected ; 1) demographic data, 2) history of bipolar disorder, 3) length of hospital stay, 4) detailed drug titration records of antimanic agents and antipsychotic agents. Results:During the last decade, the frequency of lithium monotherapy was decreased obviously. Instead, more than half of the patients in 2000 were on combination therapy of lithium and anticonvulsants. Lithiumvalproate combination was the preferred strategy and the use rate of carbamazepine has been decreased. In addition, most of the patients were given antipsychotic agents during the last 10 years. And recently, atypical antipsychotics were increasingly prescribed. These changes in the field of pharmacology of bipolar disorder have resulted neither in shorter hospital stays nor lower dosages of concurrent neuroleptics. Conclusions:The results indicate the trends in the prescribing of antimanic agents for the treatment of bipolar disorder in Korea across the past 10 years. Mostly, the change seems to correspond to the international practice guideline. More systematic research is needed to find out the clinical benefits of the anticonvulsants in the real practice of treatment of bipolar disorder.

• 한국자동차공학회논문집
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• 제22권4호
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• pp.65-71
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• 2014

As an important component of a fuel cell, the bipolar plate comprises a large proportion in the fuel cell's volume, weight and price. The bipolar plate is the most widely used; however, graphite bipolar plate is large in volume, brittle and therefore easily broken during assembling. In addition, due to its poor machinability, production costs a lot, unless mass production. Compared with the graphite bipolar plate, the metal bipolar plate has good machinability, high electric conductivity and strong mechanical strength; however, it corrodes easily and has a high contact resistance, so in order to prevent corrosion and reduce the contact resistance, the basic metal needs to be processed by use of electro polishing and coating. The water which is produced by electrochemical reactions in the fuel cell must be discharged smoothly. In this study, in order to prevent corrosion the processes of electro polishing and CrN coating were used. According to the presence or absence of these processes, the contact angles can be measured and different metal bipolar plates can be made, these plates can be used for comparing and analyzing the performance of the fuel cell.