• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.361-365
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• 2005

Since the fuel cell uses the hydrogen for its fuel. it has no emission and higher efficiency than an internal combustion engine. Also fuel cell is much quieter than engine generator and generates heat much less than engine generator. So it has advantage of Army's 'si lent watch' capability and the ability to operate undetected by the enemy. The fuel cell hybrid system combines a fuel cell power system with an ESS. The ESS (e.g., batteries or ultracapacitors) reduces the fuel cell's peak power and transient response requirements. It allows the fuel cell to operate more efficiently and recovery of vehicle energy during deceleration. The battery has high energy density, so it has the advantage regarding driving distance. However, it has a disadvantage considering dynamic characteristic because of low power density. One other hand. the ultracapacitor has higher power density, so it can handle sudden change or discharge of required power. Yet. it has lower energy density. so it will be bigger and heavier than the battery when it has the same energy. This paper proposes the power management strategy for multi-power source fuel cell hybrid system. which is applied with the merits of both battery and ultra capacitor by using both of them simultaneous.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.207-216
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• 2016

A gerotor is suitable for miniature manufacturing because it has high discharge per 1 cycle and a simple structure, while also being widely used for lubrication oil of engines and as a hydraulic source of automatic transmission. In the automobile industry, improvements in fuel efficiency and noise reduction have recently come to the fore. It has also been necessary to continuously improve the flow rate and noise of internal gear pumps for better fuel efficiency through optimal gerotor and port shape design. In this study, to develop an optimal gerotor with a new lobe shape, 2-ellipses-combined, the equation of the lobe shape was derived, and CFD analysis results were compared for 2-ellipses with those of the previous gerotors (3-ellipses and ellipse1-involuteellipse2). A performance test for the oil pump with the optimal rotor (2-ellipses) was carried out and showed good agreement with the results obtained from CFD analysis.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.83-84
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• 2008

인구의 증가로 인한 전력수요의 증가는 가공 및 지중 송진설비의 대용량화로 이어져왔다. 그러나 최근 도시 경관과 전자파로 인한 건강 등에 대한 관심이 급증하면서 주거지 주변 송전선로 실리에 대한 민원이 증가하고 있다 을에 대한 대안으로 대용량 전력송전이 가능하고 가공 및 지중송전의 단점을 보완한 가스결연 송전선로(Gas Insulated Transmission Line, GIL)가 개발되었다. 선진국에서는 가스 절연으로 우수한 절연성능과 안정성을 가지며, 기존 교통용 터널 또는 지하 전력구에 설치함으로써 주변 경관을 해치지 않고 낮은 전계 형성 등의 장점을 가진 가스절연송전선로의 연구와 개발에 많은 노력 기울이고 있다[$1{\sim}5$]. 본 논문에서는 전력기기들의 결함진단에 많이 사용되는 부분방전 측정을 가스절연 송전선로에 적용할 수 있는 최적의 측정용 센서를 개발하여 유사한 구조를 가지는 75kV GIS Mock-up과 Free moving particle 모의 방전 셀을 이용하여 발생시킨 부분방전 신호를 측정하여, 광대역 특성을 보이는 대수주기 패치 안테나와의 성능을 비교하였다.

• Journal of Chest Surgery
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• v.47 no.5
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• pp.468-472
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• 2014

Diffuse refractory vascular spasms associated with coronary bypass artery grafting (CABG) are rare but devastating. A 42-year-old male patient with a past history of stent insertion was referred for the surgical treatment of a recurrent left main coronary artery disease. A hemodynamic derangement developed during graft harvesting, necessitating a hurried initiation of cardiopulmonary bypass (CPB). Although CABG was carried out as planned, the patient could not be weaned from the bypass. An emergency coronary angiography demonstrated a diffuse spasm of both native coronary arteries and grafts. CPB was switched to the femorofemoral extracorporeal membrane oxygenator (ECMO). Although he managed to recover from heart failure, his discharge was delayed due to the ischemic injury of the lower limb secondary to cannulation for ECMO. We reviewed the case and literature, placing emphasis on the predisposing factors and appropriate management.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.173-179
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• 2009

Recently, the super capacitor(EDLC) which has drawn attention as a new energy storage element has a lot of advantage such as no maintenance, long lifetime and quick charge/discharge characteristics with large current. The objective of this paper is propose a parameter measurement method to detect the changes in equivalent series resistor (ESR) and the capacitance value of a super capacitor in order to analysis the internal characteristic and worn-out state of a super capacitor. For proposed method, only the capacitor voltage measurement using simple analog switch is required. In addition, experimental results of voltage sag compensation system in order to compensate the input voltage drop during short-term power interruption adopted super capacitor are presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.611-615
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• 2004

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above all, Electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. The electrodeless fluorescent lamp is intended as a high efficacy replacement for the incandescent reflector lamp in many applications. Therefore, the electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours. In this paper, electron temperature and electron density were measured in a radio-frequency inductively coupled plasma using a Langmuir probe method for emission characteristics. Measurement was conducted in an argon discharge for pressure from 10 [mTorr] and input RF power 100 [W] to 150 [W]. As for the electron density, a electron temperature was more distinguished for a emission characteristic. The results of ideal may contribute to systematic understanding of a electrodeless fluorescent lamps of emission characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.653-657
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• 2004

In this study, PD(partial discharge) signals which occurrs at stator coil of traction Motor are acquired. these data are used for classifying the PD sources. W(Neural Network) has recently applied to classify the PB pattern. The PD data are used for the learning process to classify PD sources. The PD data come from normal specimen and defective specimens such as internal void discharges, slot discharges and surface discharges. PD distribution parameters are calculated from a set of the data, which is used to realize diagnostic algorithm. NN which applies distribution parameters is useful to classify the PD patterns of defective sources generating in stator coil of traction motor.

• Archives of Craniofacial Surgery
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• v.19 no.2
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• pp.143-147
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• 2018

We present a patient who showed a sterile abscess after facial bone fixation with bioabsorbable plates and screws. He had zygomaticomaxillary complex and periorbital fracture due to falling down. The displaced bones were treated by open reduction and internal fixation successfully using bioabsorbable plate system. However, at postoperative 11 months, abrupt painless swelling was noted on the previous operation sites, left lateral eyebrow and lower eyelid. By surgical exploration, pus-like discharge and degraded materials were observed and debrided. The pathologic analysis revealed foreign body reaction with sterile abscess. This complication followed by bioabsorbable device implantation on maxillofacial bone surgery has been rarely reported in which we call attention to the maxillofacial plastic surgeons.

• 한국전기화학회:학술대회논문집
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• 2001.11a
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• pp.145-161
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• 2001

Novel characterization of thermal properties of a battery has been introduced by defining its frequency-dependent thermal impedance function. Thermal impedance function can be approximated as a thermal impedance spectrum by analyzing experimental temperature transient which is related to the thermal impedance function through Laplace transformation. In order to obtain temperature transient, a process has been devised to generate external heat pulse with heating wire and to measure the response of battery. This process is used to study several commercial Li-ion batteries of cylindrical type. The thermal impedance measurements have been performed using potentionstat/galvanostate controlled digital signal processor, which is more commonly available than flow-meter usually applied for thermal property measurements. Thermal impedance spectra obtained for batteries produced by different manufactures are found to differ considerably. Comparison of spectra at different states of charge indicates independence of thermal impedance on charging state of battery. It is shown that thermal impedance spectrum can be used to obtain simultaneously thermal capacity and thermal conductivity of battery by non-linear complex least-square fit of the spectrum to thermal impedance model. Obtained data is used to simulate a response of the battery to internal heating during discharge. It is found that temperature inside the battery is by one-third larger that on its surface. This observation has to be considered to prevent damage by overheating.

• Parasites, Hosts and Diseases
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• v.50 no.2
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• pp.143-146
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• 2012

Diphyllobothrium latum infections in 4 young Korean men detected from 2008 to 2012 are presented. Three were diagnosed based on spontaneously discharged strobila of the adult worm in their feces, and 1 case was diagnosed by finding the worm at colonoscopy examination in a local clinic. The morphologic characteristics of the gravid proglottid and eggs were consistent with D. latum. All patients were treated with praziquantel 15 mg/kg, and follow-up stool examinations were done at 2 months after the medication. The main clinical complaints were intermittent gastrointestinal troubles such as indigestion, abdominal distension, and spontaneous discharge of tapeworm's segments in their feces. The most probable source of infection was the flesh of salmon or trout according to a patient's past history. These are the 45th to 48th recorded cases diagnosed by the adult worm in the Republic of Korea since 1971.