• Journal of Power Electronics
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• 제11권4호
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• pp.408-417
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• 2011

The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. The PHEV battery would be recharged from the power grid at home or at work and would thus allow for a reduction in the overall fuel consumption. This paper proposes an integrated power electronics interface for PHEVs, which consists of a novel Eight-Switch Inverter (ESI) and an interleaved DC/DC converter, in order to reduce the cost, the mass and the size of the power electronics unit (PEU) with high performance at any operating mode. In the proposed configuration, a novel Eight-Switch Inverter (ESI) is able to function as a bidirectional single-phase AC/DC battery charger/ vehicle to grid (V2G) and to transfer electrical energy between the DC-link (connected to the battery) and the electric traction system as DC/AC inverter. In addition, a bidirectional-interleaved DC/DC converter with dual-loop controller is proposed for interfacing the ESI to a low-voltage battery pack in order to minimize the ripple of the battery current and to improve the efficiency of the DC system with lower inductor size. To validate the performance of the proposed configuration, the indirect field-oriented control (IFOC) based on particle swarm optimization (PSO) is proposed to optimize the efficiency of the AC drive system in PHEVs. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point, where the PSO is applied to evaluate the optimal flux. Moreover, an improved AC/DC controller based Proportional-Resonant Control (PRC) is proposed in order to reduce the THD of the input current in charger/V2G modes. The proposed configuration is analyzed and its performance is validated using simulated results obtained in MATLAB/ SIMULINK. Furthermore, it is experimentally validated with results obtained from the prototypes that have been developed and built in the laboratory based on TMS320F2808 DSP.

• 대한지역사회영양학회지
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• 제21권6호
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• pp.520-532
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• 2016

Objectives: The objective of this study was to assess energy expenditure and metabolic cost (METs) of walking activities of college students and to compare treadmill based walking with self-selected hallway walking. Methods: Thirty subjects (mean age $23.4{\pm}1.6years$) completed eight walking activities. Five treadmill walking activities (TW2.4, TW3.2, TW4.0, TW4.8, TW5.6) were followed by three self-selected hallway walking activities, namely, walk as if you were walking and talking with a friend: HWL (leisurely), walk as if you were hurrying across the street at a cross-walk: HWB (brisk) and walk as fast as you can but do not run: HWF (fast) were performed by each subject. Energy expenditure was measured using a portable metabolic system and accelerometers. Results: Except for HWF (fast) activity, energy expenditures of all other walking activities measured were higher in male than in female subjects. The lowest energy expenditure and METs were observed in TW2.4 ($3.65{\pm}0.84kcal/min$ and $2.88{\pm}0.26METs$ in male), HWL (leisurely) ($2.85{\pm}0.70kcal/min$ and $3.20{\pm}0.57METs$ in female), and the highest rates were observed in HWF (fast) ($7.72{\pm}2.81kcal/min$, $5.84{\pm}1.84METs$ in male, $6.65{\pm}1.57kcal/min$, $7.13{\pm}0.68METs$ in female). Regarding the comparison of treadmill-based walking activities and self-selected walking, the energy expenditure of HWL (leisurely) was not significantly different from that of TW2.4. In case of male, no significant difference was observed between energy costs of HWB (brisk), HWF (fast) and TW5.6 activities, whereas in female, energy expenditures during HWB (brisk) and HWF (fast) were significantly different from that of TW5.6. Conclusions: In this study, we observed that energy expenditure from self-selected walking activities of college students was comparable with treadmill-based activities at specific speeds. Our results suggested that a practicing leisurely or brisk walking for a minimum of 150 minutes per week by both male and female college students enable them to meet recommendations from the Physical activity guide for Koreans.

• 한국도로학회논문집
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• 제8권2호
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• pp.23-30
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• 2006

상온아스팔트 혼합물은 생산공정이나 시공 중에 naphtha나 kerosene을 사용하는 컷백 아스팔트와 같이 환경오염물질을 생성하지 않고 골재와 아스팔트 바인더를 가열하지 않기 때문에 가열아스팔트 혼합물에 비하여 환경친화적이며 경제적이다. 그러나 일반적으로 상온아스팔트 혼합물은 가열아스팔트 혼합물에 비해 내구성이나 수분민감성에서 미흡한 점이 많다. 본 연구에서는 상온아스팔트의 수분민감성과 내구성을 증진시킬 수 있는 섬유보강 상온아스팔트 혼합물(FEAM)에 대한 평가를 하였다. 최적 유화아스팔트량(OEC), 최적함수량(OWC) 그리고 최적 섬유보강제 첨가량(OFC)를 결정하기 위해서 마샬배합설계를 수정 개발하였다. 최적의 섬유보강 상온아스팔트 혼합물과 일반 상온아스팔트 혼합물을 제작하여 마샬안정도 시험, 간접인장강도 시험 및 회복탄성계수 시험을 실시하였고 그 결과를 가열아스팔트 혼합물의 결과와 비교하였다. 결과로 FEAM과 EAM 모두 마샬배합설계 기준으로 중간 교통량에 충분한 것으로 판명되었다. 또한 섬유보강에 의하여 일반 상온아스팔트 혼합물의 수분민감성과 내구성이 증진하는 효과도 얻을 수 있는 것으로 판명되었다

• Asia pacific journal of information systems
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• 제17권2호
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• pp.29-47
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• 2007

Owing to the rapid growth of using the Internet, not only click-and-mortar companies but also brick-and-mortar ones have been expanding their distribution channels into online, Moreover, since online channels are more attractive than offline ones in control and maintenance, switching customers into online ones is emerged as one of very important managerial issues in a view of reduction of cost as well as expansion of services. However, the switched customers should be faced by uncertainties which could not have been experienced in offline. Specifically, in online channels, buyers and sellers are separated temporally and spacially and there are always so many kinds of threat for security as well as not enough systems and conventions for them yet. Therefore, trust has been considered as one of the most critical mechanisms for resolution of such uncertainties in online transactions. However, it is not easy to build and maintain the relationships in online since most of them are virtual and indirect generally. Therefore, in order to switch offline customers into online ones, it is very important to make strategies based on identification of the relationship between online transaction and offline trust which has been built in offline business. Generally offline trust, which has been built independent of online, could not include trust for online-dependent activities such as payment security during or after transactions, while most of online trust include it. Therefore, a customer with high offline trust does not always perceive high security and assure safe transactions. Accordingly, while online trust, where technical capabilities for online security is one of main bases, includes control trust implicitly or explicitly, offline trust does not. However. in spite of such clear discrimination and independence between offline trust and perceived security, there can be the significant dependency between these two beliefs. The customers with high offline trust believe that the company would do some activities for online security for customers' safe transactions since it has been believed of doing well for customers' trust. Theoretically, users' perception of security is interpreted as a kind of control trus, which is trust for company's technical control capacities in order to resolve technical uncertainties in online. Therefore, the relationship between two beliefs can be considered as transference from offline trust to another type trust. that is, control trust. The objective of this study is to analyze the effect of offline trust on online transaction uses mediated by perceived security. For this purpose, we suggest a research model based on technology acceptance model (TAM). Reuse intention is adopted as a dependent variable and TAM is modified by adding perceived risk (PR) as well as two beliefs of using Internet banking, perceived usefulness (PU) and perceived ease of use (PEOU). Moreover, perceive security (PS) is adopted as an external variable for PR and PU, while offline trust (OT) is an antecedent of PS. For an empirical test, sampling from 108 visitors to the banks in Daegu, Korea, we analyze our model by partial least square (PLS) approach. In result, our model is shown to explain 51.4% of the variance in reuse intention and all hypothesis are supported statistically. A theoretical implication of this study is to identify a role of PS between offline trust and reuse intention of using online transaction services. According to our result, PS can be considered as a mediation variable for bridging between two different concepts: trust that explains social aspects of customers and companies, and TAM that explains customers' reuse intention.

• 지역연구
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• 제32권2호
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• pp.3-13
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• 2016

본 연구에서는 부산에 있는 국가기록원에 보관중인 북한 지역 지적측량원도 299,688매를 디지털화하는 사업의 편익을 분단 상태에서도 발생하는 편익과 통일 이후에 발생하는 편익으로 나눠서 추정하였다. 분단상태에서도 발생하는 편익은 고유가치, 유산가치, 직 간접 이용가치, 군사적 전략적 가치, 통일 기반 조성으로 나눌 수 있다. 통일 이후의 편익은 토지 원소유권 확인을 위한 행정 비용 절감, 가계(家系) 확인, 지번부여와 지적관리 업무의 토대 조성, 도시계획적 활용 등이 있다. 실제 추정은 조건부가치추정법(CVM)의 단일경계모형을 사용하였다. 분단 상태에서 발생하는 편익에 대한 가구당 지불용의액은 향후 5년간 매년 7,925원이며, 총 편익은 5,868억 원으로 추정되었다. 통일 이후에 발생하는 편익에 대한 가구당 지불용의액은 8,023원이며, 토지 원소유권 반환여부에 따라 총 편익은 3,243~5,941억 원으로 추정되었다.

• 대기
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• 제16권1호
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• pp.33-48
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• 2006

A classification of snowfall type based on development mechanism is proposed using previous snowfall studies, operational experiences, etc. Five types are proposed: snowfall caused by 1) airmass transformation (AT type), 2) terrain effects in a situation of expanding Siberian High (TE type), 3) precipitation systems associated with extratropical cyclones (EC type), 4) indirect effects of extratropical cyclones passing over the sea to the south of the Korean peninsula (ECS type), and 5) combined effects of TE and ECS types (COM type). Snowfall events during 1981-2001 are classified according to the 5 types mentioned above. For this, 118 events, with at least one station with daily snowfall depth greater than 20 cm, are selected. For the classification, synoptic weather charts, satellite images, and precipitation data are used. For TE and COM types, local sea-level pressure chart is also used to confirm the presence of condition for TE type (this is done for events in 1990 and thereafter). The classification shows that 109 out of 118 events can be classified as one of the 5 types. In the remaining 8 events, heavy snowfall occurred only in Ullung Island. Its occurrence may be due to one or more of the following mechanism: airmass transformation, mesoscale cyclones and/or mesoscale convergence over the East Sea, etc. Each type shows different characteristics in location of snowfall and composition of precipitation (i.e., dry snow, rain, and mixed precipitation). The AT-type snowfall occurs mostly in the west coast, Jeju and Ullung Islands whereas the TE-type snowfall occurs in the East coast especially over the Young Dong area. The ECS-type snowfall occurs mostly over the southern part of the peninsula and some east cost area (sometimes, whole south Korea depending on the location of cyclones). The EC- and COM-type snowfalls occur in wider area, often whole south Korea. Precipitation composition also varies with the type. The AT-type has a snow ratio (SR) higher than the mean value. The TE- and EC-type have SR similar to the mean. The ECS- and COM-type have SR values smaller than the mean. Generally the SR values at high latitude and mountainous areas are higher than those at the other areas. The SR value informs the characteristics of the precipitation composition. An SR value larger than 10 means that all precipitation is composed of snow whereas a zero SR value means that all precipitation is composed of rain.

• 대한치과의사협회지
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• 제49권2호
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• pp.77-84
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• 2011

The benefits of implant supported overdenture are readily apparent for the fully edentulous patients and have been well documented, however, there is deficiency of the studies regarding the combination of implants with removable partial dentures for partially edentulous patients. The purpose of this article is to review the literature concerning implants with removable partial dentures and evaluate the evidence for this clinical approach. Through many clinical case reports and studies we have searched from a broad variety of journals, we present the six considerations needed to contemplate respecting implants with removable partial denture in partially edentulous patients. First, the connection between abutment tooth and removable partial denture has to be rigid and the link between implant and removable partial denture should be hinged. Second, a mesial rest acts better in the point of force distribution for distal extension removable partial denture and splinting between implants is also a favorable choice. Third, T bar has an advantage for implants which are used as abutments in distal extension removable partial denture. Forth, as we all known functional impression is better way to reproduce movement for distal extension removable partial denture. Fifth, indirect retainer and guiding plane on the proximal surfaces of terminal abutment teeth are important in preventing denture base lifting. Sixth, implants in conjunction with removable partial denture is superior in the esthetic and phonetic as well as cost-effective point of view. We also suggest that which place we should install implants for force distribution and which diameter and length of implants should be used. in this review article, we recommend to locate the implant near of the abutment tooth for esthetics or near of first molar position for good stress distribution. The diameter and length of implant also influence to stress distribution. When we compare to conservative partial denture, patients go for removable partial denture using implants due to convenience, better support and retention according to several studies. But it is true that we need to study more on this subject and collect long term follow up cases before we discuss on it. So it is enough to bring this subject into the surface of prosthetic treatment by this article.

• KDI Journal of Economic Policy
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• 제36권2호
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• pp.175-196
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• 2014

본 논문은 한국 사회학계에서 사회관계망을 긍정적, 부정적 의미로 구분하는 연결망과 연줄망 개념을 이론적으로 이해하려는 시도이다. 이를 위해 일방적인 도움의 교환이라는 측면에 주목하여 사회관계망의 역할과 출현 가능한 규범에 대하여 논의한다. 사회관계망은 경제주체들의 행위에 대한 정보를 유통시키는 망으로서, 사회관계망 내에서 도움의 교환을 활성화시키는 역할을 하며, 이를 기초로 도움을 교환하는 규범이 출현한다. 그런데 사회관계망에서 도움의 교환을 지속시키기 위해서는 규범을 어겼을 때의 손실을 강화해야 하며, 이로 인해 비효율적인 도움의 교환이 가능할 수도 있다. 비효율적인 도움의 교환은 사회관계망으로부터의 이탈과 그로 인한 사회관계망의 붕괴를 가져올 수 있는데, 이 경우 사회관계망의 유지를 위해서 모두에게 손해인 배타적인 규범, 즉 연줄망이 등장한다.

• Nuclear Engineering and Technology
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• 제39권1호
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• pp.31-42
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• 2007

Energy supply is increasingly showing up as a major issue for electricity supply, transportation, settlement, and process heat industrial supply including hydrogen production. Nuclear power is part of the solution. For electricity supply, as exemplified in Finland and France, the EPR brings an immediate answer; HTR could bring another solution in some specific cases. For other supply, mostly heat, the HTR brings a solution inaccessible to conventional nuclear power plants for very high or even high temperature. As fossil fuels costs increase and efforts to avoid generation of Greenhouse gases are implemented, a market for nuclear generated process heat will be developed. Following active developments in the 80's, HTR have been put on the back burner up to 5 years ago. Light water reactors are widely dominating the nuclear production field today. However, interest in the HTR technology was renewed in the past few years. Several commercial projects are actively promoted, most of them aiming at electricity production. ANTARES is today AREVA's response to the cogeneration market. It distinguishes itself from other concepts with its indirect cycle design powering a combined cycle power plant. Several reasons support this design choice, one of the most important of which is the design flexibility to adapt readily to combined heat and power applications. From the start, AREVA made the choice of such flexibility with the belief that the HTR market is not so much in competition with LWR in the sole electricity market but in the specific added value market of cogeneration and process heat. In view of the volatility of the costs of fossil fuels, AREVA's choice brings to the large industrial heat applications the fuel cost predictability of nuclear fuel with the efficiency of a high temperature heat source tree of Greenhouse gases emissions. The ANTARES module produces 600 MWth which can be split into the required process heat, the remaining power drives an adapted prorated electric plant. Depending on the process heat temperature and power needs, up to 80% of the nuclear heat is converted into useful power. An important feature of the design is the standardization of the heat source, as independent as possible of the process heat application. This should expedite licensing. The essential conditions for success include: ${\bullet}$ Timely adapted licensing process and regulations, codes and standards for such application and design ${\bullet}$ An industry oriented R&D program to meet the technological challenges making the best use of the international collaboration. Gen IV could be the vector ${\bullet}$ Identification of an end user(or a consortium of) willing to fund a FOAK

• 기술혁신학회지
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• 제22권3호
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• pp.362-381
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• 2019

본 논문에서는 기술혁신에 영향을 미치는 요인 중 산업별 혁신시스템과 R&D 지원서비스의 요인이 엔유씨전자의 사례에서 어떻게 작용하는지 살펴보았다. 엔유씨전자는 투입구 변경과 착즙률 개선의 기술혁신을 통해 높은 혁신성과를 달성하였다. 이는 산업별 혁신시스템의 각 구성요소가 엔유씨전자의 기술혁신과 부합하는 측면이 있었기 때문이다. 엔유씨전자의 성과향상은 자체적인 혁신노력과 함께 정부출연연구소의 R&D 지원서비스가 있었기 때문에 가능했다. 기술혁신 과정에서 제품설계와 가상실험 등 기업 스스로 해결할 수 없는 영역의 고차원적인 서비스를 받을 수 있었다. 중소기업에게 부족한 부분을 보완해주는 정부와 공공기관의 지원 역할이 중요했다고 할 수 있다. 산업별 혁신시스템의 각 구성요소별로 보면 새로운 기술기회가 많은 만큼 지속성이 낮다, 모방이 쉽고 전유성이 낮지만 복합적인 측면도 있다, 기술축적의 누적성은 비교적 높은 편이다, 외부지식의 활용 가능성이 높다, 주체와 네트워크 모두 중요한 역할을 하였다, 시장여건이 매우 유리하였다 등으로 요약될 수 있다. R&D 지원서비스의 측면에서는 직접적인 효과로서 스크류의 재질과 형상에 대한 가상실험을 통해 엄청난 시간과 비용의 절약이 이루어졌다는 점을 들 수 있다. 간접적인 효과로서는 외부지원에 의한 기술개발을 계기로 엔유씨전자의 자체적인 핵심역량이 크게 강화되었고 혁신의 선순환구조가 정착되었다는 점을 들 수 있다.