• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2234-2237
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• 2008

Approximate equations for cylindrical breakdown voltages of planar pn junctions are proposed and verified. The equations show good agreement with the Baliga's results for $r_{j}/Wpp{\leqq}0.3$ and with numerical results for $r_{j}/Wpp{\geqq}0.3$ within 1% error. Sensitivity of the breakdown voltage with respect to the doping concentrations is successfully derived using the approximate equations. The sensitivity formula can be utilized in the area of tolerance design of power semiconductor devices.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.9-17
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• 2005

Recently, there are rapid development of information and communication technology and rapid growing of e-business users. We propose a method for security problem on the internet environment which changes from wire internet to wireless internet or wire/ wireless internet. Wireless e-business adopts credit card WPP protocol and AIP protocol proposed by ASPeCT. WAP, one of the protocol used by WPP has weakness of leaking out information from WG which connected wire and wireless communication. Certification chain based AIP protocol requires a lot of computation time and user IDs are known to others. We propose a Micro-Payment protocol based on credit card. Our protocol use the encryption techniques of the public key with ID to ensure the secret of transaction in the step of session key generation. IDs are generated using ECC based Weil pairing. We also use the certification with hidden electronic sign to transmit the payment result. The proposed protocol also solves the privacy protection and Non-repudiation problem.

• Horticultural Science & Technology
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• v.33 no.6
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• pp.947-954
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• 2015

To select suitable spray chrysanthemum cultivars for Agrobacterium-mediated transformation, thirty-nine (39) spray cultivars bred in the National Institutes of Korea and a standard cultivar Jinba from Japan were collected and tested for regeneration rate and Agrobacterium infection assays. MS medium with $0.5mg{\cdot}L^{-1}$ IAA and $1.0mg{\cdot}L^{-1}$ BAP was used for shoot regeneration from leaf disks and internodes. The shoot regeneration rate in leaf disks was the highest in cultivar BRM, followed by cultivars VS, WW and YTM. The cultivar JB (Jinba) used as a transformation material in previous reports ranked similarly to cultivars PK and SPP. In shoot regeneration from internodes, the shoot regeneration rate was the highest for cultivar PA, followed by cultivar WW. The infection rate of leaves and internodes of 40 chrysanthemum cultivars with agrobacterium was investigated. Cultivars WPP, YNW, VS, PP, WW, FA, PA and YMN showed the highest infection levels in leaves, whereas cultivars WPP, PA, PK and YNW had the highest infection levels in internodes. Considering all of these results, cultivars VS and WW were the most appropriate for gene transformation of chrysanthemum using leaves, while cultivar PA was for internodes.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1021-1028
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• 2013

The frequency of a power system should be kept within limits to produce high-quality electricity. For a power system with a high penetration of wind generators (WGs), difficulties might arise in maintaining the frequency, because modern variable speed WGs operate based on the maximum power point tracking control scheme. On the other hand, the wind speed that arrives at a downstream WG is decreased after having passed one WG due to the wake effect. The rotor speed of each WG may be different from others. This paper proposes an algorithm for assigning the droop of each WG in a wind power plant (WPP) based on the rotor speed for the virtual inertial control considering the wake effect. It assumes that each WG in the WPP has two auxiliary loops for the virtual inertial control, i.e. the frequency deviation loop and the rate of change of frequency (ROCOF) loop. To release more kinetic energy, the proposed algorithm assigns the droop of each WG, which is the gain of the frequency deviation loop, depending on the rotor speed of each WG, while the gains for the ROCOF loop of all WGs are set to be equal. The performance of the algorithm is investigated for a model system with five synchronous generators and a WPP, which consists of 15 doubly-fed induction generators, by varying the wind direction as well as the wind speed. The results clearly indicate that the algorithm successfully reduces the frequency nadir as a WG with high wind speed releases more kinetic energy for the virtual inertial control. The algorithm might help maximize the contribution of the WPP to the frequency support.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12C
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• pp.1692-1706
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• 2004

Recently, there are rapid development of information and communication and rapid growth of e-business users. Therefore we try to solve security problem on the internet environment which charges from wire internet to wireless internet or wire/wireless internet. Since the wireless mobile environment is limited, researches such as small size, end-to-end and privacy security are performed by many people. Wireless e-business adopts credit card WPP protocol and AIP protocol proposed by ASPeCT. WAP, one of the protocol used by WPP has weakness of leaking out information from WG which conned wire and wireless communication. certification chain based AIP protocol requires a lot of computation time and user IDs are known to others. We propose a Micro-Payment protocol based on credit card. Our protocol use the encryption techniques of the public key with ID to ensure the secret of transaction in the step of session key generation. IDs are generated using ECC based Weil Paring. We also use the certification with hidden electronic sign to transmit the payment result. The proposed protocol solves the privacy protection and Non-repudiation p개blem. We solve not only the safety and efficiency problem but also independent of specific wireless platform. The protocol requires the certification organization attent the certification process of payment. Therefore, other domain provide also receive an efficient and safe service.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.496-503
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• 2015

In order to let a wind generator (WG) support the frequency control of a power system, a conventional inertial control algorithm using the rate of change of frequency (ROCOF) and frequency deviation loops was suggested. The ROCOF loop is prevailing at the initial stage of the disturbance, but the contribution becomes smaller as time goes on. Moreover, its contribution becomes negative after the frequency rebound. This paper proposes an inertial control algorithm of a wind power plant (WPP) using the maximum ROCOF and frequency deviation loops. The proposed algorithm replaces the ROCOF loop in the conventional inertial control algorithm with the maximum ROCOF loop to retain the maximum value of the ROCOF and eliminate the negative effect after the frequency rebound. The algorithm releases more kinetic energy both before and after the frequency rebound and increases the frequency nadir more than the conventional ROCOF and frequency loops. The performance of the algorithm was investigated under various wind conditions in a model system, which includes a doubly-fed induction generator-based WPP using an EMTP-RV simulator. The results indicate that the algorithm can improve the frequency drop for a disturbance by releasing more kinetic energy.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.181-182
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• 2015

In a power system with a high wind power penetration level, the output power of a wind power plant (WPP) might give negative impacts on the frequency control of a power system. This paper proposes a power smoothing scheme of a wind turbine generator (WTG) to reduce the frequency deviation. To do this, an additional control loop is used, the output of which depends on the frequency deviation. The gain of the additional loop is determined depending on the kinetic energy (KE) of a WTG; in the under frequency condition, the gain is set to be proportional to the releasable KE of a WTG; otherwise, it is set to the maximum value. The performance of the proposed scheme is investigated for 100-MW doubly-fed induction generator based WPP using an EMTP-RV simulator under various wind conditions. The results show that the proposed scheme successfully reduces the frequency deviation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1732-1742
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• 2003

WPP protocol based a Credit card payment in mobile Internet uses WTLS which is security protocol of WAP. WTLS can't provide End­to­End security in network. In this paper, we propose a protocol both independent in mobile Internet platform and allow a security between user and VASP using Mobile Gateway in AIP. In particular, our proposed protocol is suitable in mobile Internet, since session key for authentication and initial payment process is generated using Weil Diffie­Hellman key exchange method that use additive group algorithm on elliptic curve.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.2
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• pp.72-77
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• 1993

This study was conducted to evaluate coated urea complex fertilizer (CUC) application for rice growth and its grain quality on clay loam (Deogpyeong series) and sandy loam (Gangseo series) in southern region of Korea, 1992. The coated urea complex fertilizer used in the experiment was CUC I and II. The CUC I is a complex fertilizer consisting of 18-12-13 for $N-P_2O_5-K_2O$ including 50% of coated urea as nitrogen source, and CUC II is the same complex fertilize as mentioned above but it contains 25% of coated urea. Seventy percent of conventional fertilizer for nitrogen level was applied as basal dose of side-band placement (SBP) and whole plowlayer placement (WPP). Greenish degree of rice leaf color at the late growth stage was high in CUC plots regardless of application method and soil series. Amount of nitrogen uptaken by the rice plant at harvesting stage was mush more in the CUC treatment compared to convential fertilizer, and also much more in CUC I than that of CUC II. In the WPP on clay loam, harvest index of CUC treatment was showed very low level, which was reduced more in CUC II plot. In the CUC treatments, perfect rice grain ratio decreased remarkably, and the notched-belly rice kernel ratios among imperfect rice grain increased drastically. In rice grain, Hon-value(Mg to K.N ratio) decreased, protein and amylose contents increased in CUC application plots in WPP. In addition, gel consitency and alkali spreading value related to eating quality in CUC plots were getting longer and lower, respectively. The yield in CUC plot was similar to conventional fertilizing, but significant decreased in SBP. As a result, the rice grain quality became poor with the coated urea complex fertilizer application, but it could be improved by incorporation with fast-release fertilizer.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.433-435
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• 2004

무선 환경에서의 전자상거래가 빠르게 성장함에 따라 종단간 보안이 필요하다. 기존 WTLS를 사용하는 WPP 프로토콜에서는 종단간 사용자 안전성을 보장하고 있지 않다. 이 논문에서는 AIP 프로토콜에서 사용자와 서비스 제공자간에 종단간 안전성이 제공되는 무선 인터넷 플랫폼에 독립적인 소액지불 프로토콜을 제안한다. 또한 인증기관이 인증과정에 참여할 경우 ID 기반 공개키 암호 시스템을 적용한 세션키를 생성하여 제안 프로토콜의 안전성 및 효율성을 분석한다.