• Journal of Nutrition and Health
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• v.46 no.3
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• pp.218-225
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• 2013

Although the functional ingredient has been evaluated by the Korea Food and Drug Administration (KFDA) based on scientific evidence, the levels of scientific evidence and consistency of the results might vary according to emerging data. Therefore, periodic re-evaluation may be needed for some functional ingredients. In this study, we re-evaluated scientific evidence for the antioxidant activity of coenzyme Q10 as a functional ingredient in health functional food. Literature searches were conducted using the Medline and Cochrane, KISS, and IBIDS databases for the years 1955-2010 with the search term of coenzyme Q10 in combination with antioxidant. The search was limited to human studies published in Korean, English, and Japanese. Using the KFDA's evidence based evaluation system for scientific evaluation of health claims, 33 human studies were identified and reviewed in order to evaluate the strength of the evidence supporting a relation between coenzyme Q10 and antioxidant activity. Among 33 studies, significant effects for antioxidant activities were reported in 22 studies and their daily intake amount was 60 to 300 mg. Based on this systematic review, we concluded that there was possible evidence to support a relation between coenzyme Q10 intake and antioxidant activities. However, because inconsistent results have recently been reported, future studies should be monitored.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.3
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• pp.120-125
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• 2002

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. In the switching-mode power converter, the output voltage is generally controlled by varying the duty ratio of main switch. When a converter operates in steady state, duty ratio of the converter is kept constant. So the power of switching noise is concentrated in specific frequencies. Generally, to reduce the EMI and improve the immunity of converter system, the switching frequency of converter needs to be properly modulated during a rectified line period instead of being kept constant. Random Pulse Width Modulation (RPWM) is performed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300V/1kW with 5%~30% white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.53.1-53.1
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• 2016

국립대구과학관 천체 관측 핵심시설인 1m 반사망원경을 개발하고 설치 완료하였다. 본 발표에서는 국립대구과학관 1m 망원경의 시스템 사양과 개발 및 설치과정을 전반적으로 기술하고 앞으로의 활용계획에 대해 소개하고자 한다. 이번에 도입된 주망원경은 지난 2014년 11월부터 광학계 및 마운트 설계를 시작으로 2016년 5월까지 약 1년 6개월의 개발기간을 거쳐 설치 완료되었다. 순수 국내기술로 개발된 주망원경은 주경 1,000mm(부경 300mm)의 유효구경을 가지며 후방초점거리가 700mm인 초점비 F/8의 리치-크레티앙 방식의 광학계로 설계되었다. 레이저 간섭계를 이용하여 거울면 전체의 형상 오차를 정밀하게 측정한 결과 주경면 PV < ${\lambda}/4$, RMS < ${\lambda}/20$, 부경면 PV < ${\lambda}/10$, RMS < ${\lambda}/50$의 형상 정밀도를 가진다. 포크형태의 경위대식 마운트 구조로 방위각, 고도 양축과 디로테이터에 각각 모터가 장착되어 움직이는 다이렉트 드라이브 방식으로 구동된다. 최대 구동속도는 $2^{\circ}/s$이상, 포인팅 정밀도는 2'이하, 10분간 추적 정밀도는 3"이하(10분간 오토가이더 추적 정밀도는 1"이하)의 구동 성능을 가진다. 제어용 컨트롤 시스템은 JTCS(Justek Telescope Control System)를 사용한다. 성능 평가를 위해 시험 관측된 10~13등급 사이 10개의 별들에 대한 FWHM 측정결과는 4~5" 범위에 있다. 앞으로 지속적인 성능 평가와 업그레이드를 통해 향후 정밀도를 높여 학술 연구용으로 공개할 예정이다. 이번 국립대구과학관 1m 주망원경의 도입으로 지역 천문교육 프로그램이 한 단계 더 도약할 수 있을 것으로 기대한다.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1100-1109
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• 2006

In this study, two different technologies which can measure temperature simultaneously at many points are introduced. One is to use a thermal sensor cable that is comprised of addressable thermal sensors connected in parallel within a single cable. The other is to use an optic fiber with Distributed Temperature Sensing (DTS) system. The difference between two technologies can be summarized as follows. A thermal sensor cable has a concept of 'point sensing' that can measure temperature at accurate position of a thermal sensor. So the accuracy and resolution of temperature measurement are up to the ability of the thermal sensor. Whereas optic fiber sensor has a concept of 'distributed sensing' because temperature is measured by ratio of Stokes and anti-Stokes component intensities of Raman backscatter that is generated when laser pulse travels along an optic fiber. It's resolution is determined by measuring distance, measuring time and spatial resolution. The purpose of this study is that application targets of two temperature measurement techniques are checked in technical and economical phases by examining the strength and weakness of them. Considering the functions and characteristics of two techniques, the thermal sensor cable will be suitable to apply to the assessment of groundwater flow, geothermal distribution and grouting efficiency within 300m distance. It is expected that the optic fiber sensor can be widely utilized at various fields (for example: pipe line inspection, tunnel fire detection, power line monitoring etc.) which need an information of temperature distribution over relatively long distance.

• Parasites, Hosts and Diseases
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• v.55 no.3
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• pp.337-340
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• 2017

Leishmaniasis is a neglected and endemic disease that affects poorest population mainly in developing countries. A lack of adequate and definitive chemotherapeutic agents to fight against this infection has led to the investigation of numerous compounds. The aim of this study was to investigate in vitro activity of boldine against Leishmania amazonensis murine cell infection. Boldine ((S)-2,9-dihydroxy-1,10-dimethoxy-aporphine) is an aporphine alkaloid found abundantly in the leaves/bark of boldo (Peumus boldus Molina), a widely distributed tree native to Chile. The in vitro system consisted of murine macrophage infection with amastigotes of L. amazonensis treated with different concentrations from 50 to $600{\mu}g/ml$ of boldine for 24 hr. Intracellular parasite destruction was assessed by morphological examination and boldine cytotoxicity to macrophages was tested by the MTT viability assay. When cells were treated with $100{\mu}g/ml$ of boldine the reduction of parasite infection was 81% compared with untreated cultures cells. Interestingly, boldine-treatment caused a concentration-dependent decrease of macrophage infection that culminated with 96% of reduction when cells were submitted to $600{\mu}g/ml$ of boldine. Cell cultures exposed to $100{\mu}g/ml$ of boldine and $300{\mu}g/ml$ of $Glucantime^{(R)}$ during 24 hr showed a significant reduction of 50% in parasitized cells compared with cell cultures exposed just to $Glucantime^{(R)}$. The study showed that treatment with boldine produces a better effect than treatment with the reference antimonial drug, glucantime, in L. amazonensis infected macrophage. Our results suggest that boldine is a potentially useful agent for the treatment of leishmaniasis.

• Journal of International Academy of Physical Therapy Research
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• v.1 no.2
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• pp.107-112
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• 2010

The majority of strokes are caused by ischemia and result in brain tissue damage, leading to problems of the central nervous system including hemiparesis, dysfunction of language and consciousness, and dysfunction of perception. The purpose of this study was to investigate the effects of Poly(ADP-ribose) polymerase(PARP) on necrosis in neuronal cells that have undergone needle electrode electrical stimulation(NEES) prior to induction of ischemia. Ischemia was induced in male SD rats(body weight 300g) by occlusion of the common carotid artery for 5 min, after which the blood was reperfused. After induction of brain ischemia, NEES was applied to Zusanli(ST 36), at 12, 24 and 48 hours. Protein expression was investigated using immuno-reactive cells, which react to PARP antibodies in cerebral nerve cells, and Western blotting. The results were as follows: In the cerebral cortex, the number of PARP reactive cells after 24 hours significantly decreased(p<.05) in the NEES group compared to the GI group. PARP expression after 24 hours significantly decreased(p<.05) in the NEES group compared to the GI group. As a result, NEES showed the greatest effect on necrosis-related PARP immuno-reactive cells 24 hours after ischemia, indicating necrosis inhibition, blocking of neural cell death, and protection of neural cells. Based on the results of this study, NEES can be an effective method of treating dysfunction and improving function of neuronal cells in brain damage caused by ischemia.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.81-81
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• 2010

전자 패키징은 미세화, 경량화, 저가화를 지향하고 신뢰성의 향상을 위해 발전해 왔다. 이러한 경향은 전자부품 자체의 성능 향상 뿐 아니라 전자부품을 장착, 고정할 수 있게 하는 인쇄회로 기판(PCB : Printed Circuit Board)의 성능에 많은 관심을 가지게 되었다. 전기적 신호의 손실을 줄이기 위해 전기, 전자 산업체에서는 가볍고 굴곡성이 우수한 연성인쇄회로기판(FPCB : Flexible PCB)과 가격이 싸고 신뢰성이 입증된 경성인쇄회로기판(RPCB : Rigid PCB)이 그 대상이다. 본 논문에서는 이 PCB중에서도 RPCB와 FPCB간의 열압착 방식으로 접합 시 전극간의 접합 양상을 보았다. 이 열압착 방식은 기존에 PCB를 접합하는데 사용하고 있는 connector를 이용한 체결법을 대체하는 기술로써 솔더를 중간층(interlayer)로 이용하여 열과 압력으로 접합하는 방식이다. 이 방식을 connector를 사용하는 방식에 비해 그 부피가 작고 I/O개수에 크게 영향 받지 않으며 자동화 공정이 쉬운 장점을 가지고 있다. 접합의 대상 중 RPCB의 경우는 무전해 니켈 금도금(ENIG : Electroless Nickle Immersion Gold)로 제작하였으며 FPCB의 경우는 ENIG와 유기보호피막(OSP : Organic solderability preservation) 처리하였다. 실험에 사용한 PCB는 $300\;{\mu}m$ pitch의 미세피치이며 솔더의 조성은 Sn-3.0Ag-0.5Cu (in wt%)과 Sn-3.0Ag (in wt%)를 사용하였다. 접합 온도와 접합 시간 그리고 접합 압력에 따라 최적의 접합 조건을 도출하였다. 접합 강도는 $90^{\circ}$ Peel Test를 통해서 측정하였으며 접합면 및 파괴면은 SEM과 EDS를 통하여 분석하였다.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.29-40
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• 2003

This study was aimed to verify a comparison by dental alloys upon the marginal fitness of dental prosthesis. Firstly, we waxed up on 45 epoxy resin dies, pressed the margin with hands, and identified the marginal fitness with microscope. And we made a single direct spruing system type of sprue by 3 dental alloys - metal crown alloys, PFM crown alloys, and gold crown alloys - each 15, total 45 waxing up, adjusting W/P ratio and invested the cast ring. Then, we made the dental prosthesis using the electric casting machine. In these processes we followed the manufacturer's instructions, in order to maintain the other conditions from the inner and outer, which included investment and burning out. After we tried on the dental prosthesis on epoxy resin dies, we have got the means of marginal gap at 9 points with same distances, around the cervical line which was checked already, using microscope($\times$300). The results of this study were as follows : 1. Metal crown alloys showed 2.9% better in marginal fitness than PFM crown alloys, and the difference was not statistically significant(P=0.497). 2. Gold crown alloys showed 31.3% better in marginal fitness than Metal crown alloys, and the difference was statistically significant(P=0.004). 3. Gold crown alloys showed 32.4% better in marginal fitness than PFM crown alloys, and the difference was statistically significant(P=0.002). 4. We saw that Gold crown alloys was the best dental alloys in the marginal fitness among the three.(P=0.049).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.7
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• pp.429-434
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• 2016

This paper deals with the characteristics of partial discharge (PD) for the purpose of a condition based maintenance (CBM) of gas insulated switchgears (GIS) in power equipment. Four types of electrode systems such as a protrusion on enclosure (POE), a particle on spacer (POS), a free particle (FP) and a Floating were designed and fabricated. PD pulses were measured using UHF sensor with a frequency range of 300 MHz~1.4 GHz and a DAQ with a sampling rate of 250 MS/s. Discharge inception voltage (DIV), discharge extinction voltage (DEV), and phase resolved partial discharge (PRPD) were analyzed depending on electrode systems. The average DIV in the POS was 28.8 kV. It was about 1.7 times higher than that in the FP, which was the lowest value of 17.2 kV. The FP shuffled and jumped at the applied voltage of 23.5 kV. Over 95% of PD pulses in the POE were generated in the negative polarity ($181^{\circ}{\sim}360^{\circ}$) of applied voltage. The results showed the phase (${\Phi}$)-magnitude (dBm) of PD pulses by UHF sensor, a cluster was formed separately depending on electrode systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.7-7
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• 2009

Lead telluride (PbTe) is a very promising thermoelectric material due to its narrow band gap (0.31 eV at 300 K), face-centered cubic structure and large average excitonic Bohr radius (46 nm) allowing for strong quantum confinement within a large range of size. In this work, we present the thermoelectric properties of individual single-crystalline PbTe nanowires grown by a vapor transport method. A combination of electron beam lithography and a lift-off process was utilized to fabricate inner micron-scaled Cr (5 nm)/Au (130 nm) electrodes of Rn (resistance of a near electrode), Rf (resistance of a far electrode) and a microheater connecting a PbTe nanowire on the grid of points. A plasma etching system was used to remove an oxide layer from the outer surface of the nanowires before the deposition of inner electrodes. The carrier concentration of the nanowire was estimated to be as high as $3.5{\times}10^{19}\;cm^{-3}$. The Seebeck coefficient of an individual PbTe nanowire with a radius of 68 nm was measured to be $S=-72{\mu}V/K$ at room temperature, which is about three times that of bulk PbTe at the same carrier concentration. Our results suggest that PbTe nanowires can be used for high-efficiency thermoelectric devices.