• Membrane Journal
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• v.32 no.2
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• pp.140-149
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• 2022

In this study, the conditions of low temperature and high pressure of biogas upgrading process using polysulfone membrane have been designed and tested to achieve the high recovery and efficiency corresponding to those of the highly selective polymeric materials. Polysulfone hollow fiber membrane with 4-component dope solution was spun via non-solvent induced phase separation. The hollow fiber membrane was mounted into a 1.5 inch housing. The effective area was 1.6 m², and its performance was examined in various operation temperatures and pressures. CO₂ and CH₄ permeances were 412 and 12.7 GPU at 20℃, and 280 and 3.6 GPU at -20℃, respectively, while the CO₂/CH₄ selectivity increased from 32.4 to 77.8. Single gas test was followed by the mixed gas experiments using single-stage and double stage where the membrane area ratio varied from 1:1 to 1:3. At the single-stage, CH₄ purity increased and the recovery decreased as the stage-cut increased. At the double stage, the area ratio of 1:3 showed the higher CH₄ recovery as decreasing the operation temperature at the same purity of CH₄ 97%. Finally, polysulfone hollow fiber membranes have yielded of both CH₄ purity and recovery of 97% at -20℃ and 16 barg.

• The Journal of Society for e-Business Studies
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• v.22 no.3
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• pp.57-74
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• 2017

The Electronic Shelf Label (ESL) is an alternative to the paper price label attached to merchandise shelves and is attracting attention as a retail IoT infrastructure that will lead the innovation of offline retail outlets. In general, when introducing a substitute product, the company tends to consider the financial factors such as the efficiency of the investment cost compared to the existing product or the reduction of the operating cost. However, considering only financial factors in the decision-making process, it may not properly reflect the various values associated with corporate strategy and the requirements of stakeholders. In this study, 8 evaluation items (Investment Cost, Operating Cost, Quality Level, Customer Management, Job Efficiency, Maintenance, Functional Expandability, and Store Image) based on BSC's 4 perspectives (Financial, Customer, Internal Business Process, Learning & Growth), and using AHP (Analytic Hierarchy Process) to measure the priorities of evaluation items for domestic small supermarket employees. As a result of the research, priority was given in order of Customer, Learning & Growth, Internal Business Process, and Financial aspects among the evaluation items for adopting the price label, and the electronic price label was supported with higher importance than the paper price label. In contrast to the priorities of the financial aspects of most prior studies, the items of Learning & growth and customer perspectives have relatively high priorities. In particular, respondents classified by job group, The priorities of the 8 evaluation items were different among the groups. These results are expected to provide implications for both companies (retail outlets) and ESL providers (manufacturers and service providers) who are considering the introduction of ESL.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.296-304
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• 1995

환경시험의 일부인 진동시험은 그 결과를 가지고 장비가 실제 운용하기 전에 진동에 대한 내구성이 있는가를 판단할 수 있는 단 하나의 방법이다. 이런 진동시험을 성공적으로 이끌어 정확한 결론에 도달하기 위해서는 아래 두 가지 문제에 대한 해결이 필수적이라고 생각한다. 첫번째는 '실제 상황을 정확히 반영할 수 있는 진동시험수준의 결정이다.' 진동시험수준이 적절하지 못하면 전체적으로나 부분적으로 과대진동시험(Overtest)을 실시하거나, 과소진동시험(Undertest)을 실시할 수 밖에 없고, 이에 따른 결과도 신뢰도가 떨어진다. 예를 들어, 과대진동시험으로 시험장비가 고장나거나, 과소진동시험으로 시험장비에 이상이 없다고 해서 실제 상황에서 이 장비가 진동에 대하여 만족할 만한 내구성을 갖는다고 누구도 말할 수 없기 때문이다. 두번째는 '정해진 진동시험수준을 진동시험기로부터 시험장비에 얼마나 정확히 전달할 수 있는가?'라는 문제이다. 실제로 원하는 진동시험수준을 한치의 오차없이 정확히 시험장비에 가하는 것은 거의 불가능하다. 특히 시험장비가 대형화 되면 될수록 문제는 더 심각하다. 결론적으로 위에 지적한 두가지 문제의 해결이 성공적인 진동시험의 열쇠이며, 또한 시험결과에 대한 신뢰성을 보장받을 수 있는 길이기 때문이다. 이번 논문에서 다루고자 하는 것은 두번째 문제인 진동시험수준의 정확한 전달을 위하여 진동시험기와 시험장비 사이를 연결해 주는 진동시험치구(Test Fixture) 개발에 관한 것이다. 실제 개발한 치구는 미군사규격(Military-Standard)과 보잉사 규격(Boeing specification) 그리고 샌디아사 규격(Sandia Corporation Standard)에 근거하여 분류하는 분류기준표에서 치구 중 가장 큰 부류(500 pounds 이상)에 속는 것으로, 현재 우리나라에서 보유하고 있는 것 중에 용량이 가장 큰 진동시험기에서 진동시험을 준비하고 있는, 체계에 전원을 공급하는 대형장비의 치구이다. 또한 실 진동시험을 실시하기 전의 모달시험과 예비시험 그리고 실 시험결과를 기술하므로써 제작된 치구의 실험적 평가를 하고자 한다.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.1
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• pp.50-60
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• 2012

This study was carried out to evaluate the ecotoxicological effects of Alum and Ferric chloride on the population of Eisenia fetida in vermicomposting of sewage sludge. Using contact filter toxicity test, it was shown that LC50 of Alum and Ferric chloride on adult Eisenia fetida were 457.4 mg $kg^{-1}$ and 1,665.2 mg $kg^{-1}$, respectively,which meant Ferric chloride had much higher acute toxicity on earthworm than Alum. Alum didn't affect on cocoon production, hatchability and number of hatched larvae of Eisenia fetida. Ferric chloride didn't have any efects on number of hatched larvae per cocoon, but reduced cocoon production and hatchability. Larval density of next generation was reduced by the food containing Alum and Ferric chloride. Above results indicated that the Alum and Ferric chloride could be one of the hazardous materials that made extinction of earthworm population when the sewage sludge treated with Alum and Ferric chloride was supplied to the earthworms.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.84-84
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• 2009

파이프라인을 건설함에 있어 가장 중요한 기술이 배관 용접기술이다. 즉 파이프와 파이프를 연결하는 작업이 공사 진척도를 결정하기 때문에, 이를 얼마나 경제적으로 신속하게 수행해 나가느냐하는 것은 건설기간 및 건설비용을 결정하는 핵심 요소이다. 가스배관 시공 원주용접 방법은 여러 가지 있는데, 현재 국내에서는 전량 수동용접을 채택하고 있다. 이 방법은 국내 가스배관을 건설한 초기부터 적용해온 것으로 우수한 품질을 확보할 수 있으며, 취약한 국내 자동화기술과 열악한 도로 매설 시공여건에서 적용하기 용이한 방안이다. 그러나 우수한 용접기량을 보유한 용접사가 점차 부족해지고, 배관시공 시간을 단축하고 비용을 줄이기 위한 필요성이 점차 커지면서 이를 해결할 수 있는 기술로서 자동원주용접방안이 있다. 이 기술들은 해외 가스배관에 이미 오래전부터 적용되어 용접부위 신뢰성과 품질 우수성을 확보하고 시공비용절감을 달성하고 있다. 자동용접을 적용하기 위해서는 용접절차를 수립하여 절차인증시험을 수행하고, 기존방안과 동일이상의 품질이 확보되며 효율성을 겸비해야만 한다. 국가 기본에너지의 안정적인 공급을 위해 적기 시공이 필요하고, 1 km당 10 억원 이상이 소요되는 배관시공비용 중 약 1/3이 용접비파괴검사 비용인 점을 감안할 때 품질이 확보되면서 경제적인 시공방안이 있다면 이를 적용하는 것이 국가 산업 경제적 측면에서 필요한 일이다. 이와 관련된 연구에서는 국내 가스배관 원주용접에 적용 가능한 용접공정을 검토하고, 용접절차를 수립하여 절차인증시험을 수행하였으며, 추가로 배관 원주 자동용접부위에 대한 기계적 특성 평가를 실시하였다. 현재 국내 건설여건과 비파괴검사 기준을 만족시키고 안전성과 효율성을 겸비한 방법으로는 초층과 2층은 수동 GTAW를 적용하고 나머지 층은 반자동 FCAW를 적용하는 방안이 적절한 것으로 판단된다. 전 층을 자동 GTAW로 용접하는 방안은 품질은 확보되지만 효율성측면에서 대형배관에는 적용하기 어려울 것으로 보이며, 해외에서 많이 사용되는 자동 GMAW 방안은 국내 비파괴검사기준을 만족시키기 어려워 검토대상에서 제외하였다. 본 논문에서는 두 가지 용접방법에 대한 용접공정개발과정과 원주용접부위 기계적 특성을 검토하여 최적방안을 제시하고자 한다.

• Membrane Journal
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• v.27 no.1
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• pp.60-67
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• 2017

Recently, the economic, social and environmental significance of the water industry is increasing significantly due to rapid global urbanization, population growth, and imbalance in demand and supply of water resulted by climate change. The type of these water industries are all different and they can be distinguished by the kinds of membranes used. Mainly, polymer materials that have excellent physical and chemical stability are used, but recently various methods of assigning hydrophilicity have been introduced due to their hydrophobic properties. In this study, hydrophilic polymers of four types were introduced into a commercially available hollow support to assign hydrophilicity. Furthermore, the morphology of the coated hollow support through FE-SEM was confirmed as well. Also the contact angle was measured to examine the degree of hydrophilicity of the coated hollow support with each polymer. Finally,.effect of different time on water permeability as well as the relationship between water permeability and hydrophilic polymers were investigated. As a result, the coating with 1 wt% of pluronic has good hydrophilicity degree, and shows the excellent water permeability without blocking the pore of the hollow fiber. Therefore, it can be concluded that the hydrophilic coating using pluronic polymer is most suitable as the water treatment.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.552-559
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• 2011

Recently, the eddy current testing(ECT), alternating current field testing, magnetic flux leakage testing and remote field testing have been used as a nondestructive evaluation method based on the electromagnetic induction phenomenon. The eddy current testing is now widely accepted as a NDE method for the heat exchanger tube in the electric power industry, chemical, shipbuilding, and military. The ECT system mainly consists of the synthesizer module, analog module, analog-to-digital converter, power supplier, and data acquisition and analysis program. In the previous study, the synthesizer module and the analog module which is essential to the ECT system were primarily developed, and in this study the data acquisition and analysis program were developed. The operation system for this program is based on the Windows 7, and optimized for the Korean users, and the specific feature of this program using setup wizard enables inspector to make a setup easily for acquisition and analysis of ECT data. In this paper, the configuration and functions of eddy current data acquisition and analysis program will be introduced.

• Particle and aerosol research
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• v.12 no.3
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• pp.95-102
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• 2016

Controlling exposures to occupational hazards is important for protecting workers. Certified facepiece respirators are recommended when engineering controls do not adequately prevent exposures to airborne nanomaterials. The objective of this study is to carry out the experimental performance test to investigate the fractional efficiencies of the filter media for two grades of facepiece respirators. Experimental performance evaluations were carried out for the test NaCl particles and silver nanoparticles. For media of respirator filter, the penetration of NaCl particles was less than 5% and the most penetrating particle size occurred at about 40 nm. For silver nanoparticles, the most penetrating particle size was about 20nm with higher efficiency than those of NaCl particles. Charge characteristics of airborne nanoparticles is important because the media of respirator filter is made by the electret filter media.

• Fire Science and Engineering
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• v.32 no.3
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• pp.116-122
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• 2018

In Chemical, Biological, Radiological and Nuclear (CBRN) disaster, integrated and optimized equipment package including stretcher, isolation unit, patient monitoring and treatment equipment is essential to achieve proper treatment and prevent secondary contamination. The purpose of this study was to evaluate the efficiency and ease of use of integrated CBRN disaster equipment package for disaster medical response. This study was a randomized crossover study using a manikin simulation for emergency medical technitian (EMT). All participants used the existing devices and prototype of integrated CBRN disaster equipment package alternately. Efficiency was measured by time from vital sign change to detection or treatment application. Ease was use was measured by questionnaires for each patient monitor, stretcher care and isolation unit. 12 EMTs were enrolled. hypoxia-detection time of integrated equipment group was significantly shorter than existing equipment group (4.9 s (3.8-3.9) vs 3.5 s (2.5-3.9), p < 0.05). There was decreasing tendency of ECG change detection and facial mask oxygen supply but no statistical significance was observed. Overall satisfaction of patient monitoring device in integrated equipment group was significantly higher than existing devices (4(3.5-5) vs 3(3-3), p < 0.05). The use of integrated CBRN disaster equipment package shortened the hypoxia detection time and improved usability of vital sign monitor compared to existing devices.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.192-207
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• 2020

Profitability of upland crops is better than paddy crops and proportion of upland is increasing. However, there is a lack of infrastructures for upland irrigation. The object of this study were to develop water supply scenarios using individual and collective agricultural wells to evaluate economic feasibility to consider geographical analysis of upland farms and water supply facilities. Cheongyang, Dangjin, Yesan, and Goesan were selected as study areas where four different crops of red pepper, chinese cabbage, apple, and bean, respectively, were mainly produced in Chungcheong province. As a result, B/C ratio was estimated as 1.49, 1.36, 1.90, and 0.71 in using individual wells scenario, and 1.45, 1.20, 1.91, and 0.65 in using collective wells scenario for red pepper, chinese cabbage, apple, and bean. It turned out that change of price effected on economic feasibility a lot for crops with low production income. As a result of evaluating economic feasibility by number of plots for developing collective well, there was no effect of economy of scale for red pepper and chinese cabbage. In case of collectivizating more than 20 upland plots, effect of economy of scale appeared for apple and bean. In conclusion, development of water using high value crops including red pepper and apple, and effect of collective well requires additory analysis of .spatial distribution of farms.