• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1868-1870
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• 2000

As a drive for an ETC (Electro-thermal Chemical) launcher, a large pulse power system of a 2.4MJ energy storage was designed, constructed and tested. The overall power system consists of eight capacitive 300kJ energy storage banks. In this paper we describe the design features, setup and operation test result of the 300kJ pulsed power module. Each capacitor bank of the 300kJ module consists of six 22kV 50kJ capacitors. A triggered vacuum switch (TVS-43) was adopted as the main pulse switch. Crowbar diode circuits, variable multi-tap inductors and energy dumping systems are connected to each high power capacitor bank via bus-bars and coaxial cables. A parallel crowbar diode stack is fabricated in coaxial structure with two series 13.5kV, 60kA avalanche diodes. The main design parameters of the 300kJ module are a maximum current of 180kA and a pulse width of 0.5 - 3ms. The electrical performances of each component and current output variations into resistive loads have been investigated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1600-1602
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• 2001

A pulsed power supply of 2.4MJ capacitor bank has been developed to make investigation into electric gun technology. It is made up of eight paralleled 300kJ modules, and can supply various shape of high current pulse by changing charging voltage, inductance, capacitance, and firing time of each module. The 300kJ module has been designed and fabricated for the maximum operating voltage of 22kV, peak current of 150kA, and pulse duration of 1msec. The experiments of the modules were done, and the equivalent circuit of the module was determined. The characteristics of the module were analyzed more deeply through the circuit simulation. The experiments of the paralleled modules with inductance of 20 $\mu$H and load resistance of 100 m$\Omega$ were performed, where the modules were discharged simultaneously and/or sequentially. The results of the experiments were analyzed. The 2.4MJ capacitor bank is currently used as the pulsed power supply for the ETCG (Electro Thermal Chemical Gun) research.

• 전자공학회논문지SC
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• 제47권5호
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• pp.18-23
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• 2010

본 논문은 유발전위(evoked potential) 뇌파인 P300에 기반한 뇌-기계 인터페이스의 실시간 구현을 위한 효율적인 알고리즘을 제안한다. P300 뇌파는 외부 시각 자극이 인간의 의지와 일치할 경우, 100-300ms 부근에서 negative pick를 갖는 특성이 있다. 이러한 특성에 기초하여 P300 뇌파의 포텐셜(potential) 감소를 감지하여 인간의 의도를 역으로 추론할 수 있으며, 이를 뇌-기계 인터페이스에 활용할 수 있다. 연구에서 P300 뇌파는 인간의 두개골 외부에 부착된 전극을 통해 얻어졌으며, 시각적 자극으로는 2차원 알파벳 신호를 사용하였다. P300 뇌파의 포텐셜 감소 검출을 위하여 뇌파 포텐셜을 자극과 연계하여 확률적으로 모델링하였다. 확률적 모델은 피실험자가 의도하는 신호의 모델(target model)과 의도하지 않는 신호의 모델(non-target model)로 구성된다. 이러한 확률적 모델에 기반하여 피실험자의 의도를 추론하기 위해서 최우추정법(maximum likelihood estimation)을 사용하였다. 실험에는 신체 건강한 성인 남자 3명이 참가하였으며, 'A'와 'E' 실험에 대한 피실험자 k의 평균 성공률은 98%, 피실험자 j의 평균 성공률 90%, 그리고 피실험자 h의 성공률은 79.8%였다.

• Archives of Pharmacal Research
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• 제27권6호
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• pp.604-609
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• 2004

A new indolinepeptide (3） was isolated, together with two known compounds, a cerebroside (1） and an alloxazine (2）, from silkworm larvae infected with Paecilomyces sp. J300. On the basis of spectroscopic data, their structures were elucidated as (4E, 8E, 25, 2＇R, 3R ）-N-2＇-hydroxy-hexadecanoyl-1-O-$\beta$-D-glucopyranosyl-9-methyl-4, 8-sphingadienine (1）, 7,8-dimethylalloxazine (2） and 3$\beta$,5-dihydroxy-1-N-methyl-indoline-2$\beta$-carbonyl amino-D-alanyl-erythro-$\beta$-hydoxyiso-leucinyl-glycine (3）.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.904-905
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• 2008

In this paper, a novel 60kV, 300A, 3kHz pulsed power supply based on IGBT stacks is proposed. Proposed scheme consists of series connected 9 power stages to generate maximum 60kV output pulse and 15kW series resonant power inverter to charge DC capacitor voltage. Each power stages are configured as 8 series connected power cells and each power cell generates up to 830VDC, 300A pulses. Finally pulse output voltage is applied using total 72 series connected IGBTs. The synchronization of gating signal is important of series operation of IGBTs. For gating signal synchronization, full bridge inverter and pulse transformer generates on-off signals of IGBT gating and specially designed gate power circuit was used.

• 대한기계학회논문집A
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• 제26권2호
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• pp.300-307
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• 2002

Partial penetration welding joint is defined as groove welds welded from one side, without steel backing or groove welds welded from both sides but without back gouging. So it has an unwelded portion at the root of the weld. Study of partial penetration weldment fracture behavior includes residual stress analysis and fracture analysis. The J-integral loses its path independency in residual stress field. Therefore, it is necessary to introduce a new J-integral, J, which is defined including the effect of plastic deformation and thermal strain. In this study, theoretical formulation and program were developed for the evaluation of J-integral for the crack tip located in the weldment. Evaluations of fracture behavior were performed for partial penetration multi-pass weldment of 25.4mm thick plate by J-integral. From a point of fracture in partial penetration multi-pass welding, it seemed to be better to control root face smaller than 6.35mm.

• 한방재활의학과학회지
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• 제21권4호
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• pp.23-40
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• 2011

Objectives: This study was designed to examine the effects of extracts of Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) on the lipid lowering, anti-oxidation and concentration of proinflammatory cytokines and was investigated on hyperlipidemic rats. Methods: Male rats weighing $182.39{\pm}4.71g$ were fed high fat diet for 8 weeks and 36 rats(above 400 g) were divided into 4 groups. Each of 9 rats was divided a control group and experimental groups. We fed a control group of rats a basal diet and administered normal saline(100 mg/kg, 1 time/1 day) for 4 weeks. And we fed each experimental group of rats basal diet and administered an extract of Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) extracts(100 mg/kg, 200mg/kg, 300 mg/kg, 300 mg/kg, 1 time/1 day) for 4 weeks. At the end of the experiment, the rats were sacrificed to determine their chemical composition. We measured lipid of plasma and liver, concentration of proinflmmatory cytokines, anti-oxidative activity and $TNF-{\alpha}$, Apo-B, Apo-E and leptin gene expression. Results: 1. Concentration of plasma free fatty(FFA) showed no significant difference in all the treatment groups. Concentration of plasma triglyceride(TG) showed a significant decrement in the 300 mg/kg in Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) groups than that of control group. 2. Concentration of plasma total cholesterol showed a significant decrement in the 200 and 300 mg/kg in Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) groups than that of control group. Concentration of plasma low density lipoprotein(LDL)-cholesterol showed a Significant decrement in the 300 mg/kg in Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) groups than that of control group. Concentration of plasma high density lipoprotein(HDL)-cholesterol showed a significant increment in the 300 mg/kg in Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) group. 3. Concentration of liver total cholesterol showed a tendence to decrease in Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) groups. Concentration of liver TG showed a significant decrement in all Ojeoksangamibang groups than that of control group. 4. Concentration of plasma and liver thiobarbituric acid reactive substance(TBARS) showed a tendence to decrease in Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) groups. 5. The values of glutathione peroxidase(GSH-Px), superoxide dismutase(SOD) and catalase(CAT) activity showed a significant increment in all Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) groups than that of control group. 6. The values of plasma aspartate aminotransferase(AST) and alanine aminotransferase(ALT) activity showed no significant different in all treatment group. 7. Concentration of plasma $interleukin(IL)-1{beta}$ showed no significant difference in all the treatment groups. Concentration of plasma IL-6 showed a significant decrement in the 300 mg/kg in Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) group than that of control group. Concentration of plasma tumor necrosis $factor-{\alpha}(TNF-{\alpha})$ a siginifant decrement in the 200 and 300 mg/kg in Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) group than that of control group. However the concentration of plasma IL-10 in the 300 mg/kg Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) groups showed a significant increment than that of control group. 9. In the analysis of reverse transcription-polymerase chain reaction(RT-PCR), gene expression of $TNF-{\alpha}$, Apo-B and Apo-E in the Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) groups showed a lower expression than that of control group. However the gene expression of leptin showed no difference in the treatment groups. 10. The ratio of $TNF-{\alpha}$, Apo-B, and Apo-E per ${\beta}-actin$ expression in the Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) groups showed a significant decrement than that of control group. However The ratio of leptin expression per ${\beta}-actin$ expression showed no significant difference among all the treatment groups. Conclusions: According to above results, in lowering lipid effect, anti-oxidation and control of pro-inflammatory cytokines production, Ojeoksangamibang($W{\check{u}}j\bar{i}s\check{a}nji\bar{a}w\grave{e}if\bar{a}ng$) gives effect.

• 소성∙가공
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• 제31권3호
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• pp.117-123
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• 2022

In this study, a commercial AZ61 magnesium alloy is extruded at 300 ℃ and 400 ℃ and the microstructures, mechanical properties, and high-cycle fatigue properties of the extruded materials are investigated. Both extruded materials have a fully recrystallized microstructure with no Mg₁₇Al₁₂ precipitates. The average grain size and maximum basal texture intensity of the extruded material increase with increasing extrusion temperature. The material extruded at 400 ℃ (AZ61-400) has higher tensile yield strength and lower compressive yield strength than the material extruded at 300 ℃ (AZ61-300) because of the stronger basal texture of the former. Because of coarser grain size, the tensile elongation of AZ61-400 is lower than that of AZ61-300. Despite the differences in microstructures and tensile/compressive properties, the two extruded materials have the same fatigue strength of 110 MPa. This is because the finer grain size of AZ61-300 causes an increase in fatigue strength, but its weaker texture causes a decrease in fatigue strength. In both extruded materials, fatigue cracks initiate at the surface of fatigue specimens at all stress amplitudes tested.

• Journal of Mechanical Science and Technology
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• 제16권7호
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• pp.902-910
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• 2002

Cast stainless steel may experience embrittlement when it is exposed approximately to 300$\^{C}$ for a long period. In the present investigation, the three classes of the thermally-aged CF8M specimen were prepared using an artificially-accelerated aging method. After the specimens were held for 300, 1800 and 3600hrs. at 430$\^{C}$, respectively, the specimens were quenched in water which is at room temperature. Load versus load line displacement curves and J-R curves were obtained using the unloading compliance method. talc values were obtained using the ASTM E813-87 and ASTM E 813-81 methods. In addition to these methods, talc values were obtained using the SZW (stretch zone width) method described in JSME S 001-1981. The results of the unloading compliance method are J$\_$Q/=543.9kJ/㎡ for virgin materials. The values of J$\_$IC/ for the degraded materials at 300, 1800 and 3600hrs. are obtained 369.25kJ/㎡, 311.02kJ/㎡, 276.7kJ/㎡, respectively. The results obtained by the SZW method are compared with those obtained by the unloading compliance method. Both results are quite similar. Through the elastic-plastic fracture toughness test, it is found that the value of loc is decreased with an increase of the aging time.

• 한국잠사곤충학회지
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• 제41권3호
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• pp.174-179
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• 1999

The genetic relationships among six Cordyceps spp. were investigated based on internal transcribed spacer sequences of ribosomal DNA .A portion of the these genes was amplified by PCR. Approximately 590 base pairs were successfully amplified, cloned, sequenced, compared. The nucleotide sequence of the six amplified fragments were aligned by the clustal W program. As a result, Cordyceps militaris shared 87, 96, 98, 90 and 97% sequences homology with Paecilomyces japonica, Paecilomyces sp. J300, Paeciomyces farinosa. Paecilomyces sp. J500 and Cordyceps sinensis, respectively. Paecilomyces japonica also shared 87, 88, 92 and 87% sequence similarity with Paecilomyces sp. J300, Paecilomyces farinosa, Paecilomyces sp. J500 and Cordyceps sinensis, repectively.