• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1450-1458
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• 2018

Commutation failures can deteriorate the availability of high-voltage direct current (HVDC) links and may lead to outage of the HVDC system. Most commutation failures are caused by voltage reduction due to ac system faults on inverter side. The commutation failure process can be divided into two stages. The first stage, from the occurrence to the clearing of faults, is called 'Deterioration Stage'. The second stage, from the faults clearing to restoring the power system stability, is called 'Recovery Stage'. Based on the analysis of the commutation failure process, this paper proposes a direct-current fuzzy controller including prevention and recovery controller. The prevention controller reduces the direct current to prevent Commutation failures in the 'Deterioration Stage' according to the variation of ac voltage. The recovery controller magnifies the direct current to speed up the recovery of power system in the 'Recovery Stage', based on the recovery of direct voltage. The validity of this proposed fuzzy controller is further proved by simulation with CIGRE HVDC benchmark model in PSCAD/EMTDC. The results show the commutation failures can be mitigated by the proposed direct-current fuzzy controller.

• Journal of Astronomy and Space Sciences
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• 제34권4호
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• pp.331-342
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• 2017

To ensure the successful launch of the Korea pathfinder lunar orbiter (KPLO) mission, the Korea Aerospace Research Institute (KARI) is now performing extensive trajectory design and analysis studies. From the trajectory design perspective, it is crucial to prepare contingency trajectory options for the failure of the first lunar brake or the failure of the first lunar orbit insertion (LOI) maneuver. As part of the early phase trajectory design and analysis activities, the required time of flight (TOF) and associated delta-V magnitudes for each recovery maneuver (RM) to recover the KPLO mission trajectory are analyzed. There are two typical trajectory recovery options, direct recovery and low energy recovery. The current work is focused on the direct recovery option. Results indicate that a quicker execution of the first RM after the failure of the first LOI plays a significant role in saving the magnitudes of the RMs. Under the conditions of the extremely tight delta-V budget that is currently allocated for the KPLO mission, it is found that the recovery of the KPLO without altering the originally planned mission orbit (a 100 km circular orbit) cannot be achieved via direct recovery options. However, feasible recovery options are suggested within the boundaries of the currently planned delta-V budget. By changing the shape and orientation of the recovered final mission orbit, it is expected that the KPLO mission may partially pursue its scientific mission after successful recovery, though it will be limited.

• 간호행정학회지
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• 제12권1호
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• pp.63-75
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• 2006

Purpose: This study was aimed to specify roles of nurses from the anesthesia and recovery room by analyzing nursing activities as well as anesthesia nursing during surgery. Method: The objects were 12 RNs working in the recovery room of a university hospital located in Incheon. Self-report was performed by measuring stop-watch for five days from May 17th to May 21st in 2004. Research method was designed to record the time and frequency of the nursing activity from anesthesia and recovery room based on nurses' statement and other references for five days. The data were analyzed with descriptive statistics, ANOVA, and t-test via SPSS Win 10.0 program. Result: Nursing activities in anesthesia recovery room were classified into two different characteristics such as direct and indirect nursing activity. The activities consisted of 11 direct nursing areas and 39 nursing activities in anesthesia preparation room. The indirect nursing was classified into 8 nursing areas and 32 nursing activities. The direct nursing was classified into 12 nursing areas and 55 nursing activity. Also, the indirect nursing was classified into 7 nursing areas and 21 nursing activities in recovery room. In terms of prevalence of nursing activities in the anesthesia preparation room, observation and cooperation of anesthesia was the most prevalent activity, drug and eqipment management the second prevalent, and drug administration the third. On the other hand, in the recovery room, the most prevalent activity was vital sign checking and observation, the second most prevalent activity informative activity, and the third body temperature control. Nursing activity time was recorded according to the nursing characteristics. In the anesthesia preparation room, the direct nursing spent for 8092.20 minutes was larger than the indirect nursing spent for 7198.50 minutes. Also, in the recovery room, the direct nursing spent for 2361.16 minutes was larger than the indirect nursing spent for 1134.13 minutes. 4. Nursing activity time was compared to duty shifts. In the anesthesia preparation room, the direct nursing was more prevalent on day shift and the indirect nursing was prevalent on evening shift. However, in the recovery room, both direct and indirect nursing activities were prevalent on day shift. Conclusion: The role of anesthesia and recovery room nurses was analysed according to the time, frequency, and its characteristics.

• 미생물학회지
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• 제12권1호
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• pp.25-30
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• 1974

It was convinced that with a relatively small capital investment and with a low operating cost, appreciable amounts of cement copper could be produced from low-grade minerals by the application of a bacterial leaching method. For the recovery of cement copper from the impure pregnant solution, direct precipitation of copper with tin plates by a bacterial leaching method was feasible. The results obtained were as follows: 1)In order to remove the cement copper from the reducing metal, aeration and agitation method were more effective and economic than shaking method. 2)The rate of copper recovery from the pregnant solution was accerelated according to increasing quantities of reducing metal. However, the excess of reducing metal reduced the grade of cement copper. 3)Among the comparative experiments of copper recovery at each reaction temperature of $10^{\circ}C$, $20^{\circ}C$, and $30^{\circ}C$, the recovery rate of copper at $30^{\circ}C$from the pregnant solution was highest. 4)Direct cementation method on iron-containing metal was an excellent method for the recovery of cement copper in bacterial leaching.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.988-992
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• 2006

In recent semiconductor manufacturing clean rooms, air washers are used to remove airborne gaseous contaminants such as $NH_3,\;SO_x$ and organic gases from outdoor air introduced into clean room. Meanwhile, there is a large quantity of exhaust air from clean room. It is desirable to recover heat from exhaust air and use it to reheat outdoor air. In the present study, an experiment was conducted to investigate the heat recovery and gas removal efficiencies of a direct atomization type heat recovery air washer.

• 한국안광학회지
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• 제18권2호
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• pp.193-196
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• 2013

목적: 눈의 광피로회복시간(photostress recovery time; PSRT) 검사를 위해 직상검안경을 대체할 수 있는 도구를 탐색해보고자 하였다. 방법: 단안 최대교정시력이 0.8~1.2인 남녀 48명(평균연령 22.88세, 96안)을 대상으로 직상검안경, 투광기, 펜라이트, 카메라 플래쉬를 사용하여 PSRT 검사를 실시하였다. 결과: 직상검안경, 투광기, 펜라이트, 카메라 플래쉬로 측정된 평균 PSRT는 각각 $27.90{\pm}18.40$초, $23.73{\pm}12.99$초, $21.31{\pm}15.57$초, $18.98{\pm}11.64$초로 측정되었다. 두 눈 중 교정시력이 1.0 이상인 눈과 1.0 미만인 눈 간의 PSRT 차이는 없었다. 우위안과 비우위안 간의 PSRT 차이도 없었다. 결론: 투광기가 직상검안경과 가장 유사한 도구로 나타났으나, 카메라 플래쉬와 펜라이트도 PSRT 검사에 유용한 것으로 판단되었다.

• 한국사회복지학
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• 제60권4호
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• pp.175-203
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• 2008

정신장애인의 회복은 정신건강상태, 긍정적 인지와 정서, 친한 사람의 수와 그 관계의 질 등 개인적, 사회적 자원을 활용하여 대처하는 중 형성되고, 이는 주관적 경험뿐 아니라 장기적 조사에 의해 지지된다. 회복을 촉진하기 위해 이 요인들 간의 유기적인 관계를 밝혀 사회복지실천 방법을 발전시킬 필요가 있다. 이에 본 연구는 460명의 지역사회 거주 정신장애인들의 낙관성, 정신건강상태, 정서, 사회적 관계의 양과 질, 대처가 어떠한 관계를 통해 회복에 영향을 주는지 구조방정식모형을 통해 살펴보았다. 연구결과, 첫째, 이론모형의 경로파악 결과 낙관성과 정서가 사회적 관계, 대처, 회복에 영향력을 행사한 한편, 정서는 대처에, 정신건강상태와 사회적 관계는 회복에 유의한 영향이 없었다. 둘째, 낙관성과 긍정적 정서는 회복에 직접 효과를 보이고, 양적, 질적 사회관계는 회복에 간접효과만 보였다. 낙관성보다는 긍정적 정서가 양적, 질적 사회관계에 직접 및 간접효과를 보이고, 회복에 더 큰 효과를 나타냈다. 끝으로, 낙관성과 회복, 양적관계와 회복, 질적 관계와 회복 각각의 관계에서는 대처가, 긍정적 정서와 대처 간에는 질적, 양적 관계가, 그리고 양적관계와 대처 간에는 질적 관계가 부분적 매개효과를 보였다. 이러한 결과에 따라 정신장애인의 회복에 영향을 미치는 긍정적 인지와 정서, 사회적 관계의 상이한 기제, 이들 자원과 대처, 회복의 관계에 대해 논의하고 사회복지실천 및 연구를 위한 함의를 제언하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.404-408
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• 2001

This paper focuses on the pilot-scale investigation of direct recycling of electric arc furnace (EAF) stainless steelmaking dust. The direct recycling of EAF dust is to make pellets with the mixture of the dust and the reducing agent carbon, then introduce the pellets to the EAF. The valuable metals in the dust are reduced and get into the steel as the alloying elements. Experiments simulating direct recycling in an EAF were performed using an induction furnace. But it seems difficult to reduce all metal oxides in the dust so that some metal reducing agents added in the late stage of reduction process. The valuable metals in the dust were reduced partly by carbon and partly by metal reducing agent for the economical concern. The recovery of iron, chromium and nickel from the flue dust and the amount of metal oxides in the slag were measured. The results showed that the direct recycling of EAF stainless steelmaking dust is practicable. It wes also found that direct recycling of flue EAF stainless steelmaking dusts does not affect the chemistry and quality of stainless steel produced in the EAF. It is benefit not only for the environmental protection but also for the recovery of valuable metal resources in this way.

• 한국병원경영학회지
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• 제16권1호
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• pp.50-76
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• 2011

This study chiefly aims to examine the relations between customer's responsive behavior and service recovery satisfaction in medical service failure. Therefore, this paper deals with the effect of medical service failure severity perceived by customers on complaint behavior and service recovery expectation, the effect of complaint appealing behavior and service recovery expectation on perceived recovery and service recovery satisfaction, and the roles of service recovery(compensation) and recovery fairness as moderating variables. According to the result of this research, it was shown that service failure severity affects complaint behavior and service recovery expectation positively, and compliant behavior and service recovery expectation affects perceived recovery performance and service recovery satisfaction positively. Moreover, the moderating roles of service recovery(compensation) and recovery fairness indicated partially significant results and affected perceived recovery performance and service recovery satisfaction direct positively. The result of this study is expected to provide support when medical institutes establish service recovery strategies.

• The Journal of Asian Finance, Economics and Business
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• 제8권9호
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• pp.11-22
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• 2021

This study investigates the long-run relationship between the de jure economic, political, and social globalization and foreign direct investments in the Gulf Cooperation Council (GCC) to establish whether policies that foster trade and investment relations among geographical entities can help revive the GCC countries from the prevailing economic debacles of the COVID-19 pandemic. This study is driven by the GCC's quest to fully overcome the economic challenges occasioned by the outbreak of the global pandemic and position itself as the most potent regional economic bloc in the Middle East and North Africa (MENA) region. The study employs the panel data of the six GCC countries of Bahrain, United Arab Emirates, Kuwait, Qatar, Oman, and Saudi Arabia from 1971 to 2017. The findings of the panel fully modified ordinary least square regression estimation show that the de jure economic and social globalization have a significant positive impact on the region's foreign direct investment inflows. The impact of the de jure political globalization on foreign direct investment is statistically significant but negatively signed. Based on the preceding findings, we offer some holistic policy recommendations to the GCC region as recipes for timely recovery from the economic impact of COVID-19 and beyond.