• 한국의류학회지
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• 제35권6호
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• pp.700-711
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• 2011

The purposes of the study were to identify the online service attributes that contribute to online consumer experiences of satisfaction, service failure, and service recovery and to examine whether differences exist in these attributes between U.S. and Korea. E-A-S-QUAL provided a useful framework for the study. Focus group interviews and web surveys were conducted by utilizing college students in both countries. No significant cultural differences were found in online service dimensions of service satisfaction. Personalization was the most frequently mentioned online service dimension of service satisfaction both in the U.S. and Korea. The findings showed significant cultural differences in terms of online service dimensions responsible for service failure and recovery. For Korean consumers, merchandising was one of the key online service dimensions of service failure, while efficiency was the important service dimension resulting in service failure for the U.S. consumers. In addition, for U.S. consumers, efficiency and personalization were the two most frequently mentioned service dimension for service recovery, while Korean consumers put more importance on the contact and information dimensions for service recovery. This study provided a comprehensive list of online service attributes important to online apparel retailing.

• 설비공학논문집
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• 제24권3호
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• pp.224-229
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• 2012

The importance of ventilation system is being emphasized by interest of indoor air quality. Especially, heat recovery ventilation system has attracted attention as most effective ventilation plan. Because it can reduce hazardous construction materials, indoor air pollutions, and also can reduce air conditioning energy cost. In heat recovery ventilator, the element core is the most important part. The element core is composed of liner and spacer. And liner and spacer are stacked alternately. On the Liner, heat and humidity transfer are made between supply and exhaust air. And spacer plays a role as a tunnel of exhaust and supply. In this study, we investigated and analyzed the efficiency of a heat recovery ventilator, when the spacer's properties are changed. As a result, difference spacer's properties affect an efficiency of heat recovery ventilator.

• 한국미생물·생명공학회지
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• 제26권3호
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• pp.206-212
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• 1998

생분해성 고분자인 poly(3-hydroxybutyrate, PHB)를 생산하는 Alcaligenes eutrophus의 배양액에 응집제를 첨가하여 회수한 균체로부터 용매추출법 에 의한 PHB 회수와 순도에 미치는 응집제의 영향을 조사하였다. 응집제는 Al계 3종류와 Fe계 2종류를 사용하였다. 균체로부터 PHB는 30%로 희석한 hypochlorite 용액과 chloloform 혼합용액을 이용하여 추출 회수하였다. Al계 응집제들의 경우, 응집제의 첨가량이 1,000 mg-Al/L 이하의 농도에서는 PHB 회수율이 응집제를 첨가하지 않은 경우의 회수율(82%)과 거의 비슷하였고, 1000 mg-Al/L 이상의 농도에서는 응집제 첨가량이 증가함에 따라 PHB 회수율이 감소하였다. PHB 추출에 사용한 hypochlorite 용액의 농도를 50%로 증가시키면, 응집제를 2000 mg-Al/L까지 높은 농도로 첨가하여도 90% 이상의 PHB 회수율을 얻을 수 있었다. 회수된 PHB의 순도는 응집제의 종류와 용량에 관계없이 98% 이상으로 매우 높았다. Fe계 응집제의 경우, 응집제의 용량은 PHB의 회수율에 거의 영향을 미치지 않았으나, 회수된 PHB중의 잔류 Fe의 농도가 높았고, 잔류 Fe에 의해 정제한 PHB가 엷은 적색으로 착색되었다. 세포의 회수와 PHB의 정제 공정에 적합한 응집제로는 응집효율, 잔류 Al과 Fe 및 정제 PHB의 색상 등을 고려할 때 Fe계 보다는 Al계 응집제가 적합하였다.

• 전력전자학회논문지
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• 제24권6호
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• pp.396-405
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• 2019

Single-phase full-bridge inverters have shoot-through problems. Dead time is an essential way of solving these issues, but it distorts the output voltage and current. Dual-buck inverters are designed to eliminate the abovementioned problems. However, these inverters result in switching power loss and electromagnetic interference due to the diode reverse-recovery problem. Previous studies have suggested reducing the switching power loss from diode reverse-recovery, but their proposed methods have complex circuit configurations and high system costs. To alleviate the switching power loss from diode reverse-recovery, the current work proposes a dual-buck inverter with a coupled inductor. In the structure of the proposed inverter, the current flowing into the original diode is divided into a new diode. Therefore, the switching power loss is reduced, and the efficiency of the proposed inverter is improved. Simulation waveforms and experimental results for a 1.0 kW prototype inverter are discussed to verify the performance of the proposed inverter.

• 한국초전도ㆍ저온공학회논문지
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• 제19권1호
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• pp.22-25
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• 2017

Steel slag has been considered as an industrial waste. A huge amount of slag is produced as a byproduct and the steel slag usually has been dumped in a landfill site. However the steel slag contains valuable resources such as iron, copper, manganese, and magnesium. Superconducting magnetic separation has been applied on recovery of the valuable resources from the steel slag and this process also has intended to reduce the waste to be dumped. Cryo-cooled Nb-Ti superconducting magnet with 100 mm bore and 600 mm of height was used as the magnetic separator. The separating efficiency was evaluated in the function of magnetic field. A steel slag was ground and analyzed for the composition. Iron containing minerals were successfully concentrated from less iron containing portion. The separation efficiency was highly dependent on the particle size giving higher separating efficiency with finer particle. The magnetic field also effects on the separation ratio. Current study showed that an appropriate grinding of slag and magnetic separation lead to the recovery of metal resources from steel slag waste rather than dumping all of the volume.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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• pp.670-675
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• 2000

The purpose of the study is development and investigation about basic performance of the system operation on a dual fueled cogeneration system(CGS), which is operated with biogas and gas oil. As often seen in dual fueled CGS performance, the electric generating efficiency was obtained about 26□. Methane contained in the biogas could not bum completely at lower load, and it was discharged into exhaust gas. Considerable amount of the methane burned in the exhaust pipe, and the heat recovery ratio was 42□ on heat balance. As a result, the total heat efficiency, which is a summation of generating efficiency and heat recovery efficiency reached to about 70□. The supply of biogas into the engine reduces smoke density and NOx concentration in exhaust gas. At lower load, methane burned slowly and large portion of it was discharged without burning. Therefore the measures are desirable that promotes combustion of methane at lower load.

• 생물환경조절학회지
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• 제12권3호
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• pp.107-113
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• 2003

본 연구에서는 온실의 온풍식 난방시스템 연통에 장착할 수 있는 폐열 회수기의 성능 개선을 목적으로 기 설계된 세 가지 열교환 장치와 기존의 장치에서 열교환 면적과 파이프의 두께 및 공기흐름 방향을 개량한 새 열교환 장치에 대해 열회수 성능을 실험적으로 비교 분석하였다. 그 결과 기존의 열 교환장치인 A형, B형 및 C형의 열회수 성능은 동일 송풍전입에서 각각 42.2%, 40.6% 및 54.4% 정도였으나 , 새로 개량된 D형은 69.2%로써 가장 현저히 높게 나타났다. 그러나 열회수용 공기의 흐름방향 변화에 따른 열회수 성능 개선효과 (A형 대비 B형)는 없는 것으로 나타나 적정 송풍기 용량이라면 직선형이 공기의 흐름방향 180${\circ}C$ 굴절시키는 헤어핀형보다 효과적인 것으로 판단된다. 결국 열회수 성능은 열회수 시스템의 열교환 면적과 열교환 파이프의 두께 및 풍속에 크게 좌우되는 것으로 나타났다. 따라서, 열교환 파이프의 내구성 등 을 고려하여 기능한 한 범위 내에서 열 교환면적을 증대시키거나 열교환 파이프의 두께를 앓게 하고 풍속을 증대시키는 것이 열회수 성능 개선효과와 직결됨을 알 수 있었다. 그리고 송풍기 용량이 필요이상으로 큰 경우, 소비전력이 많게 되는 등의 문제가 있기 때문에 적정용량 및 제품의 안정성을 고려하여 선택해야 할 것으로 판단되었다.

• 설비공학논문집
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• 제17권11호
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• pp.998-1004
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• 2005

Recently natural ventilation rate is decreased due to the airtightness of apartment building. Therefore the use of heat recovery ventilator (HRV) has been greatly increased as an alternative method to supply fresh air and save energy in the building. In this research the experiment standard of HRV is compared between KS and JIS and the sensitivity analyses are experimented by both standards. Under cooling experiment condition indoor and outdoor wet-bulb temperature difference of JIS is 2 to 3 times higher than that of KS. It shows that the efficiency measurement of HRV by KS is expected to have greater sensitivity than by JIS and thus accurate measurement of web-bulb temperature is required. The experimental results provide that the efficiency of thermal exchange is resemblance to each others between KS and JIS. Under cooling experiment condition the efficiency of humidity exchange by KS presents higher than by JIS, however, under heating experiment condition the efficiency by KS shows lower than by JIS, reversely.

• Membrane and Water Treatment
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• 제10권3호
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• pp.201-206
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• 2019

In this study, we performed an electrowinning process for effective removal of metals (Cu and Ni) in solution and their recovery as solid forms. A complete removal of Cu and Ni (1,000 mg/L) was observed during four times recycling test, indicating that our electrowinning system can ensure the efficient metal removal with high stability and durability. In addition, we investigated effect of operation parameters (i.e., concentration of boric acid only for Ni, variation of pH, concentration of electrolyte ($H_2SO_4$), and cell voltage) on the efficiency of metal removal (Cu and Ni) during the electrowinning. The addition of boric acid significantly enhanced removal efficiency of Ni as the concentration of boric acid increased up to 10 g/L. Compared to negligible pH effect (pH 1, 2, and 4) on the Cu removal, we observed the increase in removal efficiency of Ni as the pH increased from 1 to 4. The electrolyte concentration did not significantly influence the removal of Cu and Ni in this study. We also obtained great removal rates of Cu and Ni at 2.5 V and 4.0 V, which were much faster than those at lower voltages. Finally, almost 99% of each Cu and Ni (1,000 mg/L) was selectively removed from the mixture of metals by adjusting pH and addition of boric acid after the completion of Cu removal. The findings in this study can provide a fundamental knowledge about effect of important parameters on the efficiency of metal recovery during the electrowinning.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.416-418
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• 2008

Cost effective and high efficiency energy recovery circuit (ERC) using an address voltage source is proposed. Different from prior ERC, the proposed circuit uses a voltage source to charge a panel and a current source to discharge the panel. As a result, it can be achieved zero voltage switching (ZVS) of switches in H-bridge inverter and zero current switching (ZCS) of switches of the ERC. Moreover, the proposed ERC can obtain high efficiency, high performance and the decrease of the cost and the size.