• Journal of the Korean association of regional geographers
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• v.15 no.6
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• pp.752-762
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• 2009

This paper aims to investigate the characteristics of location and business-services networks of venture firms in Daegu region. The regional venture firms are small scale and consist of mainly R&D investment and license new-technology in the category of soft-ware. Since the mid-1990's the firms that were founded by people with higher education and career experience seek diverse growth strategies. those firms concentrate in some regions of dalseo-gu and buk-gu. There are a few difference by types of firm-business, but, on the whole, the princepal location factors of venture firms are accessibility of research institute and university, easy information availability, and use of moderate land. In regard to networks with client firms, the venture firms determine whether to transfer. The result of the characteristics of networks between regional venture firms and business-service enterprises is as follows; the regional venture firms utilize small number of business-service enterprises and use mainly information processing and other computer operation related services and professional, scientific and technical services. In business-service be used by regional venture firms, the frequency of information processing and other computer operation related services, research and development, business support services is much, while the frequency of professional, scientific and technical services is little. Business-service enterprises are distributed mostly in Daegu region and are used owing to lack of technology and knowledge.

• Journal of the Korean Vacuum Society
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• v.20 no.4
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• pp.307-312
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• 2011

As a technique for removing cancerous tumors from normal tissue, radio-frequency electromagnetic waves were employed to heating target cells up to the critical temperature, which kills the cancerous cells. However, its use in treating tumors in soft organs is limited by inconvenient factors, which are use of high-currents and long time operation. In this work, the feasibility of the localized heating by inserting four conducting electrodes with tiny direct current is investigated. The heat source is resulting from the electric field as known as resistive heating. We have investigated the temperature distribution as a function of applying DC voltages ranging from 10 V to 30 V with 10 V step. From the simulation results, the mushroom-like lesion shape by applying 20 V is generated by four electrodes within a few minutes, that is proper to the clinical application.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.1
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• pp.39-44
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• 2003

As the portable electronic equipments are developed and popularized, the batteies are more important. To prolong life of the equipments, engineers demand to have batteries of high-power density and they are used to use Li-ion batteries popularly Li-ion batteries are better than conventional batteries, Ni-cd, about power density per volume and weight, but they have a fault that discharge voltage of them goes down. In order to maximize life of the Li-ion batterries, we have to use a converter which is suitable for the characteristic of Li-ion batteries. Therefore, capacitive idling SEPIC(Single Ended Primary Inductance Converter) that is derived from the SEPIC topology is proposed as a source of the Portable low-power applications. The converter has characteristics of buck-boost porformance. Besides, that makes it possible to increase the switching frequency by partial soft commutation of power switches through adding a diode and a switch. This paper is presented the characteristics, DC voltage conversion ratio, circuits of operation modes, of the converter and it is analized and implemented.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.5
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• pp.419-426
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• 2002

A new active lossless snubber for half-bridge dual converter(that is called'dual converter') is proposed in this paper It features soft switching(ZVS) as well as turn-off snubbing in both main and auxiliary switches. Therefore, it helps the dual converter to operate at the higher frequency with a higher efficiency and smaller-sized reactive components. Moreover, since it uses parasitic components, such as leakage inductances and switch output capacitances etc, to achieve the ZVS of power switches, it has simpler structure and lower cost of production. The operational principle, theoretical analysis, and design consideration are presented. To confirm the operation, features, and validity of the proposed circuit, experimental results from a 200w, 24V/DC-200V/DC proto-type are presented.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.428-431
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• 2009

Purpose: Blow out fracture resulting from facial trauma is of high frequency among facial bone fractures, and can cause severe complications. So, proper management and close observation after operation are needed. So far, Computed tomography has been the best choice in the evalution following orbit wall reconstruction. However, cost - effectiveness, accessibility to patients and hazard of radiation exposure of computed tomography require supplementary measure for the evaluation following orbit wall reconstruction. This study was performed to describe the effectiveness of ultrasonography in the evalution following orbit wall reconstruction. Methods: A retrospective study was performed on 40 patients who underwent orbit wall reconstruction from June, 2008 to July, 2008. The patients' ages ranged from 13 to 65 years (mean 27.5 years), and this group was compsoed of 27 male and 13 female patients. The follow up period ranged from 2 weeks to 28 weeks (mean 11weeks). Preoperatively, all fractures were diagnosed using computed tomography. Ultrasonography for all cases, and computed tomography for 2 cases were performed for evaluation following orbit wall reconstruction. Results: Reduction of herniated orbital soft tissue and orbit implant was identified by using ultrasonography in 38 cases out of 40 cases. In other cases which we could not identify the orbit implant, computed tomography was performed. Con clusion: Compared to computed tomography, ultrasonography is simple, inexpensive and convenient method. Ultrasonography can be used as supplementary measure to computed tomography in the evaluation following orbit wall reconstruction for elective patients.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.3
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• pp.147-154
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• 2003

This paper presents a high-frequency boost type ZVS-PWM chopper-fed DC-DC power converter with a single active auxiliary edge-resonant snubber at the load stage which can be designed for power conditioners such as solar photovoltaic generation, fuel cell generation, battery and super capacitor energy storages. Its principle operation in steady-state is described in addition to a prototype setup. The experimental results of boost type ZVS-PWM chopper proposed here, are evaluated and verified with a practical design model in terms of its switching voltage and current waveforms, the switching v-i trajectory and the temperature performance of IGBT module, the actual power conversion efficiency, and the EMI of radiated and conducted emissions, and then discussed and compared with the hard switching scheme from an experimental point of view. Finally, this paper proposes a practical method to suppress parasitic oscillation due to the active auxiliary resonant switch at ZCS turn-off mode transition with the aid of an additional lossless clamping diode loop, and can be reduced the EMI conducted emission.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1296-1302
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• 2016

A hardware implementation of ultra-lightweight block cipher algorithm PRESENT that was specified as a block cipher standard for lightweight cryptography ISO/IEC 29192-2 is described in this paper. Two types of crypto-core that support master key size of 80-bit are designed, one is for encryption-only function, and the other is for encryption and decryption functions. The designed PR80 crypto-cores implement the basic cipher mode of operation ECB (electronic code book), and it can process consecutive blocks of plaintext/ciphertext without reloading master key. The PR80 crypto-cores were designed in soft IP with Verilog HDL, and they were verified using Virtex5 FPGA device. The synthesis results using $0.18{\mu}m$ CMOS cell library show that the encryption-only core has 2,990 GE and the encryption/decryption core has 3,687 GE, so they are very suitable for IoT security applications requiring small gate count. The estimated maximum clock frequency is 500 MHz for the encryption-only core and 444 MHz for the encryption/decryption core.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.3
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• pp.284-289
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• 2011

Lesch-Nyhan syndrome is a disease caused by metabolic disorder of purine. General muscle stiffness and hyposomia are shown from infancy and symptoms can include involuntary or irregular movements of arms and legs, mental retardation, and compulsive self-mutilating behaviors. Self-mutilating behaviors begin at approximately the first year or sometimes at late teens. The patients bite their lips, especially lower lip, tongue, buccal mucosa, hands and fingers. Tongue and lips can be injured or mutilated in severe cases. As the patient gets older, self-mutilating behaviors become more serious and extensive and secondary infection of injured areas is possible. Periodic soft tissue damage due to self-mutilating may evolve to cancer. Medical treatment, appliance treatment, extraction of tooth and surgical operation was attempted to control self-mutilaing behaviors. We hereby report the case of child Lesch-Nyhan syndrome patient who has self-inflicted labial damage as chief complaint. When patient was treated with conservate therapy, such as removable or fixed appliance, the frequency of labial damage could be subdued and yielded favorable results.