• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.432.1-432.1
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• 2014

Hydroxyapatite (Ca10(PO4)6(OH)2) is known as the main inorganic component of mature mammalian bones and teeth. Because of its biocompatibility, hydroxyapatite has attracted much attention due to its potential applications in many biomedical researches. Here, we tested a therapeutic potential for the use of hydroxyapatite as an anticancer drug delivery vector. We prepared various types of hydroxyapatite having different chemical contents and morphologies using hydrothermal synthesis. The capability of hydroxyapatite as drug delivery materials was examined by adsorption kinetics of 5-fluorouracil molecules, a common anticancer drug, in phosphate buffered saline. We find that hydroxyapatite with smaller crystal size and higher phosphate contents shows improved adsorption property. Given that hydroxyapatite provides a scaffold for bone regeneration, these results highlight a potential use of hydroxyapatite in therapies aimed at osteosarcoma.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.203-205
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• 2002

Light is an environmental signal that regulates photomovement and main energy source of photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803 (Syn6803). Syn6803 is a popular model system for study of plant functional genomics. In this report, we adopted 2D gel based proteomics study to investigate proteins related with the light absorption and photo-protection in Syn6803. More than 700 proteins were detected on the SDS-gels stained with silver nitrate. Several proteins showing different expression level under various light conditions were identified with MALDI-TOF Mass spectrometry. As a comparison, we also conducted ICAT-based proteome study using WT and cphl (cyanobacterial phytochrome 1) mutant. A cphl deletion led to changes in the expression of proteins involved in translation, photosynthesis including photosystem and CO2 fixation, and cellular regulation. We are currently involved in TAP-tagging method to study protein-protein interactions in search for the molecular component involved in the light signal transduction of Syn6803 photomovement.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.99-103
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• 2003

Recently, a fuel cell with low voltage and high current of electronic output characteristics is remarkable for new generation system. It needs both a dc-dc boost converter and do-ac inverter to be used in domestic power. Therefore, this paper presents do-dc boost converter with ZVS for fuel cell generation system This topology has several advantages, which are ZVS characteristics of all of main and auxiliary switches, reduction of reactor component size because of high frequency switching, and low rated voltage stress of the switches. In this paper, theoretical analysis, operation principle, and design procedures are presented. And simulation results from Pspice are presented to validate the theoretical analysis.

• Journal of Power Electronics
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• v.12 no.3
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• pp.458-467
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• 2012

Single phase converters suffer from ripple power pulsating at twice the line frequency. The ripple power is usually absorbed by a bulky capacitor bank and/or a dedicative LC resonant link, resulting in a low power density and a high cost. An alternative solution is using a dc link active power filter (APF) to direct the pulsating power into another energy-storage component. The main dc link filter capacitor can then be reduced substantially. Based on a mainstream dc APF topology, this paper proposed a new control strategy incorporating both dual-loop control and repetitive control. The circuit parameter design is also re-examined from a control point of view. The proposed APF scheme has better control performance, and is more suited for high power applications since it works in CCM and with a low switching frequency.

• Journal of Information Processing Systems
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• v.10 no.3
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• pp.459-470
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• 2014

In this paper, the average probability of the symbol error rate (SER) and throughput are studied in the presence of joint spectrum sensing and data transmission in a cognitive relay network, which is in the environment of an optimal power allocation strategy. In this investigation, the main component in calculating the secondary throughput is the inclusion of the spatial false alarms, in addition to the conventional false alarms. It has been shown that there exists an optimal secondary power amplification factor at which the probability of SER has a minimum value, whereas the throughput has a maximum value. We performed a Monte-Carlo simulation to validate the analytical results.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.177-182
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• 2002

This paper presents the loss analysis of Three Level Converter. Three Level DC/DC Converter presented in this paper used a phase shift control with a flying capacitor in the primary side to achieve ZVS for the outer switch. This converter reduces the voltage stress across the main switch to half of input voltage. This paper analyses the loss of each component and the various losses in the circuit assessed. The result of the analysis are verified using 2.5kW prototype.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06d
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• pp.190-195
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• 2010

Vehicular ad hoc networks (VANETs) have a number of interesting applications to preserve road safety, notify users about changed road/traffic condition, handling post accident hazards and moreover service oriented applications to make the travel convenient to the drivers. Use of common information format for diverse applications enables the application developers to easily design flexible information dissemination system for new applications or add new features to existing application. This paper introduces a common information format for various applications in VANETs. The main goal of the paper is to design generalized distributed architectures for vehicular networks, which considers diverse application development scenarios and uses common information format. The proposed architectures enable the application developers to flexibly disseminate information to affected or interested user. In this paper, we have given a detail description of each component of the architectures and how they communicate with each other. In future, we will implement the proposed architecture using suitable simulator.

• Journal of the Korean institute of surface engineering
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• v.38 no.6
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• pp.216-226
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• 2005

Pb-Free Technology was born with environmental problems of electronic component, Being connected by big and small project of every country. Also, in each country environment is connected and various standards of IEC, ISO, MIL, JIS, KS, JEDEC, EIAJ etc. All products can divide at solder part and finishing part These can tested each and synthetically divide. This research is reliability evaluation for three kind of ph-free SnCu solder plating solution and it's deposit. First, executed analysis about Pure Sn, SnCu solutions and plating surface by way similar to other plating solution analysis. Next, executed reliability about test method and equipment for reliable analyzer system construction. Next, data comparison and estimation, main estimation test method and item's choice. In this paper the systematic surface analysis and reliability for plating solutions and it's deposit in metal surface finishing processes could be shown.

• Journal of the Korean institute of surface engineering
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• v.46 no.4
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• pp.158-161
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• 2013

Recently, the weight reduction and miniaturization of the electronics have placed great emphasis. The miniaturization of PCB (Printed Circuit Board) as main component among the electronic components has also become progressed. The use of acid copper plating process for Via-Filling effectively forms interlayer connection in build-up PCBs with high-density interconnections. However, in the case of copper-via filled in a bath, which is greatly dependent on the effects of additives. This paper discusses effects of Cl ion on the filling of PCB vias with electrodeposited copper based on both electrochemical experiment and practical observation of cross sections of vias.

• Ocean and Polar Research
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• v.24 no.3
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• pp.313-318
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• 2002

The basic magnetic properties are reported for Eocene andesite and granitic andesite collected from the King Sejong Station and Marsh Runway at King George Island, South Shetland Islands Antarctic Peninsula. Samples A (andesite), B (granitic andesite) and D (granitic andesite) carry stable component of natural remanent magnetization (NRM), but sample C (andesite) unstable URM. These NRM stabilities are consistent with the domain structures estimated by the ratios of $J_R/J_s\;and\;H_{RC}/H_C$ values. On the basis of their Curie temperature, we infer magnetite as the main magnetic carrier for samples A B and C and titanomagnetite for sample D. Our study reveals that samples A and B are suitable for paleomagnetic investigations, whereas sample D is not.