• 설비공학논문집
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• 제24권8호
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• pp.605-611
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• 2012

The objective of this study is to investigate the influence of the cooling performance for a water-to-water 10 RT ground source heat pump by using the water switching and refrigerant switching method. The test of water-to-water ground source heat pump was measured by varying the compressor speed, load side inlet temperature, and ground heat source side temperature. The cooling capacity and refrigerant mass flow rate of the heat pump increased with increasing ground heat source temperature. But COP of the heat pump decreased with increasing ground heat source temperature. As a result, the water switching method with counter flow, compared to a refrigerant switching method, improves the cooling capacity and COP by approximately 6~9% in average, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.337-338
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• 2008

We have studied electro-optic characteristics of a high performance liquid crystal display using Fringe In-plane field Switching (FIS) mode. The strong electric fields cause more liquid crystals to reorient almost in plane above and between the pixel electrodes. As a result, the operation voltage is lower and transmittance is higher than those of Fringe Field Switching (FFS) and In-Plane Switching (IPS) modes. Apparently, the transmittance depends on voltage applied at the configurations of FIS mode which are proposed. Therefore, we have studied certain length of between electrodes for maximum transmittance and light intensity.

• Journal of Power Electronics
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• 제6권2호
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• pp.95-103
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• 2006

In this paper, a novel prototype of auxiliary switched capacitor assisted voltage source soft switching PWM Single-Ended Push Pull (SEPP) series capacitor compensated load resonant inverter with two auxiliary edge resonant lossless inductor snubbers is proposed and discussed for small scale consumer high-frequency induction heating (IH) appliances. The operation principle of this inverter is described by using switching mode equivalent circuits. The newly developed multi resonant high-frequency inverter using trench gate IGBTs can regulate its output AC power via constant frequency edge-resonant associated soft switching commutation by using an asymmetrical PWM control or duty cycle control scheme. The brand-new consumer IH products which use the newly proposed edge-resonant soft switching PWM-SEPP type series load resonant high-frequency inverters are evaluated using power regulation characteristics, actual efficiency vs. duty cycle and input power vs. actual efficiency characteristics. Their operating performance compared with some conventional soft switching high-frequency inverters for IH appliances is discussed on the basis of simulation and experimental results. The practical effectiveness of the newly proposed soft switching PWM SEPP series load resonant inverter is verified from an application point of view as being suitable for consumer high-frequency IH appliances.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권1호
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• pp.66-79
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• 2008

Several oxides have recently been reported to have resistance-switching characteristics for nonvolatile memory (NVM) applications. Both binary and ternary oxides demonstrated great potential as resistive-switching memory elements. However, the switching mechanisms have not yet been clearly understood, and the uniformity and reproducibility of devices have not been sufficient for gigabit-NVM applications. The primary requirements for oxides in memory applications are scalability, fast switching speed, good memory retention, a reasonable resistive window, and constant working voltage. In this paper, we discuss several materials that are resistive-switching elements and also focus on their switching mechanisms. We evaluated non-stoichiometric polycrystalline oxides ($Nb_2O_5$, and $ZrO_x$) and subsequently the resistive switching of $Cu_xO$ and heavily Cu-doped $MoO_x$ film for their compatibility with modem transistor-process cycles. Single-crystalline Nb-doped $SrTiO_3$ (NbSTO) was also investigated, and we found a Pt/single-crystal NbSTO Schottky junction had excellent memory characteristics. Epitaxial NbSTO film was grown on an Si substrate using conducting TiN as a buffer layer to introduce single-crystal NbSTO into the CMOS process and preserve its excellent electrical characteristics.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권12호
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• pp.777-784
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• 1999

Since the ultra-high voltage power apparatus are recommended to withstand switching surge generated from the electric power system, the switching impulse voltage is generally used to verify this requirement at the testing laboratories. Recently, the international standard(IEC 60060-2) related to the high voltage measurement techniques is revised requiring a traceability of measuring system for high voltage measurements. In this paper, a reference divider for switching impulse voltage is developed satisfying the revised. IEC standard and the possibility of applications has been investigated. Therefore, the characteristics of the high and low voltage side resistor and the shielding ring have been analyzed including the step response characteristics of the prototype divider. Throughout various efforts, it is confirmed that our measuring device has shown compatible characteristics as a reference divider.

• 전력전자학회논문지
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• 제20권4호
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• pp.313-320
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• 2015

This study deals with a bidirectional interleaved soft switching DC-DC converter for a wide range of input voltages. The proposed converter operates in complementary switching with the purpose of inductor size reduction and zero-voltage switching (ZVS) operation. The current ripple related to complementary switching is minimized by three-phase interleaved operation. The main characteristics of the proposed topology are its soft-switching method of operation and its simple structure. The soft-switching operation and the system efficiency of the proposed converter are verified by experimental results.

• 한국콘텐츠학회논문지
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• 제16권4호
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• pp.301-312
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• 2016

본 연구는 호텔기업에서 고객들이 경험하는 소비특성이 재방문의도와 전환의도에 어떤 영향을 미치는지 살펴보고, 또한 고객들의 방문횟수에 따라서 재방문의도와 전환의도에 미치는 영향력이 조절되는지 검증하여 마케팅 전략 측면에 실무적 시사점을 제공하고자한다. 이를 위해서 국내 특1, 2급 호텔을 이용한 고객 534명을 대상으로 실증분석 하였고, 그 결과는 다음과 같다. 첫째, 호텔의 경험적 소비특성 중에서 유희성, 상징성, 유익성, 심미성이 재방문의도에 정(+)의 영향을 미치는 것으로 나타났다. 둘째, 호텔의 경험적 소비특성 중에서 상징성, 유익성, 심미성만이 전환의도에 부(-)의 영향을 미치는 것으로 나타났다. 더불어 재방문의도와 전환의도에 가장 큰 영향을 미치는 경험적 소비특성은 상징성임을 알 수 있었다. 셋째, 호텔의 경험적 소비특성 중 유희성, 공유성과 재방문의도의 영향관계는 방문횟수에 따라 조절되며, 호텔의 경험적 소비특성 중 유희성, 상징성과 전환의도와의 관계역시 방문횟수에 따라 조절되는 결과를 보였다. 이런 결과를 바탕으로 호텔기업에서는 효율적인 마케팅 전략을 수립할 수 있을 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권1호
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• pp.145-164
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• 2014

Network virtualization provides a promising tool to allow multiple heterogeneous virtual networks to run on a shared substrate network simultaneously. A long-standing challenge in network virtualization is the Virtual Network Embedding (VNE) problem: how to embed virtual networks onto specific physical nodes and links in the substrate network effectively. Recent research presents several heuristic algorithms that only consider single topological attribute of networks, which may lead to decreased utilization of resources. In this paper, we introduce six complementary characteristics that reflect different topological attributes, and propose three topology-aware VNE algorithms by leveraging the respective advantages of different characteristics. In addition, a new KS-core decomposition algorithm based on two characteristics is devised to better disentangle the hierarchical topological structure of virtual networks. Due to the overall consideration of topological attributes of substrate and virtual networks by using multiple characteristics, our study better coordinates node and link embedding. Extensive simulations demonstrate that our proposed algorithms improve the long-term average revenue, acceptance ratio, and revenue/cost ratio compared to previous algorithms.

• 대한전자공학회논문지
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• 제17권6호
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• pp.86-92
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• 1980

다단스위칭 회로를 구성하고 있는 트랜지스터의 스위칭 동작을 베이스전압과 단위 스텝 응답함수의 특성을 고려하여 해석 하였으며 트랜지스터의 축적시간을 고려하면 트랜지스터를 시간지연소자로 간주할 수 있다고 보고 이를 이용하여 IC화 할 수 있는 시간지연 회로 및 발진회로를 제시하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.2039-2041
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• 1998

In this paper, Operation characteristics of the active clamp(ACL) zero-voltage-switching(ZVS) forward converter(FC) and active clamp hard- switching(HS) forward converter are compared with respect to loss analysis. The losses of semiconductor (including conduction losses and switching losses), transformer(containing the core loss and copper loss) and parasitic element of passive element (capacitor, inductor) are measured and compared for each type. For an experiment we have built 50W ACL ZVS-FC and ACL HS-FC, in which the switching frequency is 200kHz, and test it. The experimental results show that both types of operation have nearly same characteristics.