• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.74-80
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• 2019

$Nafion/TiO_2$ composite membranes were prepared via an in-situ sol-gel process with different immersing periods from 1 day to 7 days for the low humidifying proton exchange membrane fuel cell. As the immersing time increased, the $TiO_2$ content within the Nafion membrane increased. The contact angle decreased with the increased $TiO_2$ content in the composite membrane due to the increased hydrophilicity. The water uptake and proton conductivity reached to the highest level for 4 day immersing period, then decreased as the immersing period increased. A 7 days of immersing time was shown to be too long because too much $TiO_2$ aggregates were formed on the membrane surface as well as interior of the membrane, interfering the proton transfer from anode to cathode. Cell performance results were in good agreement with those of the water uptake and proton conductivity; current densities under a relative humidity (RH) of 40% were 0.54, 0.6, $0.63A/cm^2$ and $0.49A/cm^2$ for the immersing time of 1, 3, 4 and 7 days, respectively at a 0.6 V. The composite membrane prepared via the in-situ sol-gel process exhibited the enhancement in the cell performance under of RH 40% by a maximum of about 66% compared to those of using the recasting composite membrane and Nafion 115.

• The Journal of the Korea Contents Association
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• v.17 no.2
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• pp.172-182
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• 2017

The purpose of this study is to learn current state of social welfare funds of 6 major cities, and to find better ways to execute those funds as well as to facilitate studies on them. So far, the studies on funds were limited to those on large ones such as pension, yielding scant number of studies on local ones, which could be the practical tools to resolve the problems of the area. To do this, I analyzed the scale of the funds (i.e. the amount of the funds raised, the amount changes in fund execution, and the comparison of the scale between each fund accounts and general accounting) and the characteristics of the fund programs (i.e. the comparison of scales of fund programs of each fund accounts, the content of the programs of each fund accounts, and the characteristics of the budget of each fund accounts). The result shows that 1) the scale of the funds changed accordingly as they were maintained, curtailed and expanded; 2) the scale of the funds were 0.02~1% of that of the general accounting; 3) the fund programs were mostly for decreasing poverty, centered on self support; 4) the social welfare funds and the funds for women were not clearly separated in some local governments, instigating the arguments on the identity of social welfare funds; and 5) the fund programs were run by civil organizations, different from general accounting programs. Based on the findings, to efficiently utilize the social welfare funds, I suggest 1) expansion of the fund scales; 2) diversification of the self-support programs to decrease poverty; 3) specification of the identity of the social welfare funds; and 4) establishment of the public and civil governance.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1001-1008
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• 1996

Staphylococcal food poisoning is the major cause of bacterial food poisoning occurring in this country. Therefore government regulates commercial foods through Official Dictionary of Food that there should be free of enterotoxigenic Staphylococcus aureus in Korean rice cakes, bread, and a box lunch. Since at least 5 days are required to identify the S. aureus by the official method in the Dictionary it is difficult to prevent the food poisoning and the investigation of the outbreaks. In this report an improved determination method of the S. aureus has been developed using polymerase chain reaction (PCR) technique. Sense and antisense primers for specific amplification of genes encoding staphylococcal enterotoxins were designed and synthesized for the PCR. Rapid chromosomal DNA isolation method was also developed from S. aureus using lysostaphin. The PCR condition was developed as follows. Reaction solution $(50\;{\mu}l)$ consisted of target DNA $2\;{\mu}l$ (about 20ng), 10X buffer $5\;{\mu}l$, primer 100pmole, dNTP (10 mM) $4\;{\mu}l$ and Taq DNA polymerase 2.5 unit in a thin-wall tube. Operation condition of the PCR was 5 min pre-denaturation at $94^{\circ}C$, 15 sec denaturation at $94^{\circ}C$, 15 sec annealing at $50^{\circ}C$, 20 sec extension at $72^{\circ}C$, and 5 min post-extension at $72^{\circ}C$, and 30 cycles of denaturation-annealing- extension. Using the PCR with Perkin Elmer GeneAmp PCR system 2400, types of enterotoxigenic S. aureus could be identified from Ddok or bread in a day.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.395-399
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• 2011

Material of the gasket for lithium ion battery requires the chemical resistance, the electrical insulting property, the compression set, the anti-contamination level and the low temperature resistance. We compounded ethylene propylene diene monomer (EPDM), which showed widely different solubility parameter index, with adjusting the amount of metal oxide as an activator. We did long-term test and compression set against an electrolyte with consideration for operating conditions in lithium-ion battery. In these tests, we checked the physical, chemical characteristics and the effect to lithium ion battery with different kinds of activators. In case of rubber with ZnO as an activator, through 1000 h depositing test in propylene carbonate which is one of representative solvents, we could get the satisfying characteristics and result. However, $Zn^{2+}$ had eluted in the ion elution test. So, ZnO should be limited in EPDM compound for the gasket material in lithium-ion battery.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.641-647
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• 2016

A drop-on-demand inkjet is used widely for various applications. Therefore, it is important to understand the jetting behavior of the drop from the piezo inkjet. In this study, to predict the jetting behavior, VOF (Volume-of-Fluid) simulation techniques were used and compared with the experimental results. The experimentally measured meniscus movement was used as the input data for the simulation. To verify the simulation, the measured jetting behavior of the mixture fluids of ethylene glycol and IPA (isopropyl alcohol), which has a mixing ratio of 50:50, was used. The numerical simulation of the drop formation using various mixture ratios and its comparison with the measured drop formation confirmed that the proposed method can predict the actual jetting. On the other hand, the satellite drop behavior showed slight differences because the small sized droplet is subject to a more aerodynamic effect during flight because the kinetic energy of the satellite droplet is far smaller than that of the main droplet.

• Journal of the Korean Solar Energy Society
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• v.35 no.5
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• pp.11-19
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• 2015

In this paper, EP-Kalina cycle applying liquid-vapor ejector and motive pump is newly proposed. In this EP-Kalina cycle, the liquid-vapor ejector is used to increase pressure difference between inlet and outlet of the turbine. Also the motive pump enhances the performance of liquid-vapor ejector, resulting in increase of system efficiency of OTEC cycles. The comparison cycles in this study are basic, Kalina, EKalina and EP-Kalina ones. The pump work, net power, APRe, APRc, TPP and system efficiency of each cycle are compared. In case of net power, EP-Kalina cycle is lowest among the cycles due to the application of the motive pump. But, the net power difference of cycles seems to be minor since the pump work of cycles is merely about 1kW, compared to turbine gross power of 20kW. The system efficiency of EP-Kalina cycle shows 3.22%, relatively 44% higher than that of basic OTEC cycle. Therefore, the system efficiency is increased by applying the liquid-vapor ejector and the motive pump. Additional performance analysis is necessary to optimize the proposed EP-Kalina cycle.

• Polymer(Korea)
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• v.34 no.5
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• pp.430-433
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• 2010

The gasket materials of for the lithium ion battery requires chemical resistance to electrolyte, electrical insulating, compression set, anti-contamination and low temperature property. To check the special characteristics of fillers which are applied to rubber for gasket, compound of EPDM, NBR and FKM (fluoro elastomer) were made by adjusting weights of carbon black and silica additive. Using these compounds, we had done tests of long-term stability against electrolyte, compression set and low-temperature property with considering operating condition of the lithium ion battery. From this test, we investigated the physical and chemical characteristics of rubber with using of carbon black and silica additive in each.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.391-394
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• 1993

For the automation of Tackjoo fermentation, a sensor measurable gas production during brewing and a controller were built. The performance tests were carried out at 10 litter Tackjoo fermentor, The sensor was consisted of a transparent acryl cell for bubble formation and photo-interrupter for the detection of bubbles of 0.018ml size. The fermentation controller was fabricated with a single chip microcomputer (MC68705R3) and provided with both the monitoring module of temperature measurement and the valve controling device for the cooling water circulation in coil type heat exchanger. The operation programs were developed and systemized in ROM. With this computer system, the gas production amount and rate were acquired during the Tackjoo fermentation. The fermentation curve based on the gas production rate showed a good agreement with that of alcohol concentration. The maximum rate of gas production was found after 24 hr at $30^{\circ}C$. The correlation equation between the gas production and alcohol concentration was established and used as the control algorithm of the fermentation.

• Food Industry
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• s.218
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• pp.24-49
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• 2010

${\bigcirc}$ 본 업소는 어묵류(튀김어묵, 찐어묵, 구운어묵)을 생산하는 식품제조 가공업소로서 총 5명의 인원이 어묵류 15개 제품을 생산하여 매출액은(약 00원)이며 주도 대형 유통판매업소에 판매하고 있다. ${\bigcirc}$ 본 업소의 어묵은 연육, 농산물 등과 식품첨가물을 배합 성형 후 가열 등의 공정을 거쳐 생산된 제품으로, 원료 취급과정에서의 오염이나 불충분한 가열, 교차오염 등으로 식중독균(병원성대장균, 황색포도상구균 등)과 원료 및 제조과정에서 이물(금속 등)이 혼입될 수 있으며, ${\bigcirc}$ 이로 인한 주요클레임 발생사례는 최근 3년간 관계당국으로부터 대장균군 검출 3건, 소비자클레임 2건이 있었다. - 연도별 주요 클레임내용은 '08년도에는 대장균군 검출 3건, '09년도 튀김어묵에서 날벌레 이물 검출 1건, '10년도에는 찐어묵에서 철수세미 1건 이었다. ${\bigcirc}$이러한 위해발생을 사전에 예방하기 위해 중점관리해야 하는 공정은 가열공정으로 판단되며, 금속등의 이물혼입 또한 중점적으로 관리할 필요성이 있다. ${\bigcirc}$ 본 업소에서 생산하는 어묵류(튀김어묵, 찐어묵, 구운어묵)는 가열공정에서의 가열온도와 시간을 각각 설정하여 CCP 1로 관리하고 있으며, 품온이 $85^{\circ}C$이상으로 유지될 수 있도록 2시간마다 모니터링하고 한계기준 이탈여부를 기록하도록 하고 있다. ${\bigcirc}$또한 금속검출공정을 CCP 2로 관리하여 2mm${\varphi}$ 이상의 금속이물 혼입여부를 상시 확인하고 있으며, 금속검출기의 정상 작동여부를 4시간마다 모니터링하고 기록하도록 하고 있다. ${\bigcirc}$종합적인 공정 및 일반위생관리를 위해 개인위생 상태 냉동, 냉장고 온도 확인 등 총 29개 항목에 대하여 정기적 점검(매일 17, 주간 4, 월간 4, 분기 1, 연간 3)을 실시하고 있으며, ${\bigcirc}$따라서 지속적인 모니터링을 통해 미흡사항의 원인으로 파악하고 문제점 제거를 위해 체계적이고 지속적인 관리가 필요하다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.519-519
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• 2013

본 연구에서는, 전기적 충격이 없고 넓은 면적을 동시에 처리할 수 있는 형태의 유전체 장벽 방전(DBD: Dielectric Barrier Discharge)을 이용한 대기압 저온 플라즈마 장치를 제작하고 이를 이용하여 빵 곰팡이(Neurospora crassa) 살균에 대한 기본 분석을 하였다. 실험에 사용한 저온 대기압 면방전 플라즈마의 파워는 사인파 교류전압을 인가하여, 방전전압은 1.4~2.3 kV, 방전전류는 20~30 mA의 값을 가지며, 전압과 전류의 위상차는 약 80도의 기울기 차이가 난다. 이때의 출력은 약 4 W를 가지며, 공랭식 쿨러를 이용하여 유전체의 열을 배출하였다. 시료대의 온도 측정결과 방전과 동시에 쿨러를 작동할 경우 최대 10분에서 37도를 넘지 않았다. 장치에서 발생하는 플라즈마에 의한 O3의 양은 플라즈마 발생부로부터 10 mm 이내에서 약 25~30 ppm 이 측정되었으며, NO나 NO2 는 거의 검지되지 않았다. 증류수(Deionized water)속에 담긴 빵 곰팡이(Neurospora crassa) 포자를 면방전 플라즈마 발생장치로 처리하였을 때, 포자의 발아율은 처리시간 및 출력파워가 증가함에 따라 급격히 감소하였으나 VM (Vogel's Minimal) 배양액에 넣고 플라즈마 처리를 한 경우에는, 증류수의 결과와 달리 살균효과가 미비함을 보였다. MTT 측정법 또한 같은 경향성을 보였으며, 이를 통해 포자를 둘러싸고 있는 환경이 플라즈마의 살균효과에 영향을 미치는 것으로 보인다. 본 실험을 통해, 유전체 장벽을 이용한 면방전 플라즈마 발생장치가 플라즈마 제트(jet)와 달리 직접적인 플라즈마 접촉 없이도 미생물 살균이 가능하다는 것을 보았으며, 처리대상의 생체용액과 같은 주변 환경에 영향을 받음을 알 수 있었다. 또한 면방전 플라즈마 장치로부터 발생하는 O3과 같은 활성종들이 빵 곰팡이의 비활성화에도 역할을 할 수 있음을 알 수 있었다.