• 약학회지
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• 제42권6호
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• pp.627-633
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• 1998

Impurity profiling analysis of methamphetamine seized in Korea was investigated for the evidential and intelligent purpose. Samples were extracted with ethylacetate which contai ns internal standard of dioctylsebacate under basic condition and extracts were analyzed by GC-FID. Ephedrine, chloroephedrine & 1,2-dimethyl-3-phenylaziridine were identified impurities in illicit methamphetamine by GC-MS. These impurities revealed that most of abused methamphetamine in Korea were synthesized from ephedrine as a starting material. For the classification of samples. firstly, 24 impurity peaks were selected after inspection of every peak in 50 samples as the specific markers of impurities. Secondly, corresponding peak retention time and area ratio to the internal standard were calculated and database was created with values of 24 peaks by in-house program. Finally, cluster analysis was attempted with the resultant profiles using the STAR plot, which was based on the Euclidian distance for evaluating similarity among samples. A total of 76 samples were divided into 8 different groups within 90% statistical similarity and inter-batch samples showed similar impurity patterns by this procedure. In conclusion, the analysis of impurities is a suitable index for estimation the common or different origin of methamphetamine sample.

• 한국응용과학기술학회지
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• 제2권2호
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• pp.47-53
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• 1985

Correlation among the wax-pigment composites which is base vehicles for the crepas was investigated in terms of fadeness. The base wax synthesized and pigments are compounded with petroleum lubricant and exposed under carbon arc individually. The yellowing phenomenon was appeared on the reference papers coated with the spindle oil which was then exposed. The papers were again extracted with distilled water and pH of them were ranged between 6.2-6.5. Color difference from Adam-Nickerson equation, ${\vartriangle}E$ of base wax is 0.15 and that of spindle oil are varied from 0.66 to 15.62. Since the main components of the petroleum lubricant are aromatic hydrocarbons which have absorptions characteric of UV ranging from 240 to 280 nm, fadeness characteristics of the composites are largely depend upon the change of molecular structure of spindle oil by absorbing UV. Thus the spindle oil having the following physical properties has the better resistance of fadness and is recommended to use in compounding the base wax-pigment composites: ${\cdot}$ main component: paraffinic hydrocarbon ${\cdot}$ pour point: below - $15^{\circ}C$ ${\cdot}$ UV absorption characteristics: ${\lambda}max.$ : 268-290nm ${\cdot}$ absorbancy: below 0.1(0.03ml of sample/50ml of $CHCl_3$)

• 한국응용과학기술학회지
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• 제10권2호
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• pp.41-47
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• 1993

Chitin was isolated from crab shells by modified Hackman's method, which was treated again with aqueous sodium hydroxide solution to give alkali chitin(sodium alkoxide of chitin). And after, the alkali chitin is allowed to react with monochloroacetic acid to synthesize 6-O-(carboxymethyl) chitin [CM-Chitin] under diminished pressure. In order to synthesize high performance CM-Chitin as hygroscopic agent, it was measured that the yield and degree of subsititution of each CM-Chitin according to molar ratio(monochloroacetic acid equivalent mol/N-acetyl-D-glucosamine residue) and their moisture-absorption and moisture-release properties were measured and compared with those of hyaluronic acid. The moisture-absorption and moisture-release properties of CM-Chitin, especially 0.8 in degree of substitution, were found quite similar to those of hyaluronic acid. The preliminary results show that CM-Chitin might be used as hygroscopic agent instead of hyaluronic acid in field of cosmetics.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.8-10
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• 2005

In a general purpose inverter, a dead-time compensation strategy is very important for reducing torque ripples and acoustic noises of motors. However, in the case of small capacity inverter, the accurate dead-time compensation is hard to be obtained because a removal of the switching noise in a feedback current signal is difficult on condition of low-cost implementation. In this paper, the operation characteristics of the general purpose inverter applied the dead time compensation algorithm using an instantaneous back calculation of the phase angle of the current are presented.

• 한국통신학회논문지
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• 제15권4호
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• pp.341-352
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• 1990

본 논문에서는 nx64Kb/s의 다윈 트래픽 수용에 있어서 분리 수용, 부분 혼합 수용, 완전 혼합 수용등의 세가지 형태의 스위치망을 제시하고 다원 트래픽의 호손을 계산 알고리즘을 사용하여 트래픽 혼합비에 따른 각 호소율계산하고 그 특성을 분석하며, 주어진 서비스 등급에서 만족되는 트래픽처리 용량을 알아 본다. 완전 혼합 수용 형태의 스위치는 비교적 적은 양의 중대역 트래픽을 갖는 ISDN 트래픽을 수용할 수 있으며, 중대역 트래픽양이 증가된 경우의 ISDN 트래픽을 수용하기 위해서는 부분 혼합 수용 형태나 분리 수용 형태의 스위치가 필요하다. 앞으로 이러한 연구결과는 다윈 트래픽을 수용하는 ISDN 스위치망 설계에 이용될 수 있을 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.828-830
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• 2003

AVR은 동기발전기의 출력전압을 부하변동에 관계없이 일정하게 제어하며 발전기 및 시스템 보호를 위한 각 종 제어 알고리즘을 구비하고 있다. 종래의 아나로그타입 AVR은 제어설정이 불편하고 제어신뢰성이 떨어지기 때문에 점차 디지털 타입으로 교체되고 있다. 본 연구는 선박발전기에 적용하기 위한 디지털 AVR 개발에 관한 것이다. TI사의 TMS320LF2407 CPU를 사용하여 제어 H/W를 개발했으며, 과여자/저여자제어, Droop제어, 무부하/역률제어 등 다양한 제어기능을 S/W로 구비하여 부하에 따른 적용의 유연성을 높였다. 그리고 전력회로는 IGBT를 사용하여 고속 스위칭 제어함으로써 SCR 방식에 비해 제어 속응성을 개선하였다. 개발 된 제품은 AVR, 직류전원공급장치 및 부하나 계통의 사고시 보호를 위한 전류부스트(CBS)기능을 포함하고 있다.

• KSBB Journal
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• 제18권4호
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• pp.312-317
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• 2003

Glycine의 배양액 첨가에 의해 Pseudomonas aurantiaca S-4380 유래 재조합 levansucrase의 세포 외 분비가 촉진된다는 것을 알 수 있었다. 배지액에 존재하는 glycine 농도에 비례 의존적으로 균체 내에서 발현된 효소의 분비량이 증가되었고, 세포의 성장은 억제됨을 알 수 있었다. SDS-PAGE 분석결과 0.5％, 1.0％ glycine 첨가로 배양시간이 증가하면서 세포내의 단백질 배양액으로 분비됨을 알 수 있었다. Levansucrase를 분비시키기 위한 최적화된 조건은 pH을 6.9-7.0으로 조절하면서 1.0％ glycine을 배양초기 첨가하였을 때 배양말기에 단백질의 급격한 분해 없이 145 U/mL의 효소 활성도를 나타내었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1447-1448
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• 2007

고출력 펄스 전원으로 PFN Marx 펄스 전원공급장치를 설계 및 제작하였다. PFN Marx는 커패시터와 인덕터 그리고 스파크 갭과 전원을 공급하는 전원공급장치와 전류 인덕터로 구성하여 제작을 하였다. 여기에 사용하는 스파크 갭 스위치는 개스를 채우는 방식으로 개스의 압력을 조정하여 스위치의 스위칭 전압을 조정하여 준다. PFN Marx는 커패시터와 인덕터가 직병렬로 구성이 되며 펄스폭과 PFN의 임피던스를 결정하는 중요한 요소이다. PFN Marx 펄스 전원공급장치를 시뮬레이션 및 제작하여 시험을 하였다. 요구되는 사양은 전압 수십 kV, 펄스 폭수백 ns이다. 본 논문에서는 PFN Marx 펄스전원장치의 설계 및 시험에 대하여 고찰하고자 한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.483-488
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• 2013

The psychoacoustic quality of ABS is now considered more important than before as the focus of recent ABS function is expanded to basic function from typical emergency function. Thus, the automotive parts manufacturing companies are actively working to improve NVH (Noise, Vibration, and Harshness) in ABS module. In terms of time, test place, and cost, however, it is very inefficient to have all the operating noise validation test in real vehicle configuration especially for partially improved ABS module. To contribute to reducing the development period and to grasping the improvements faster, this research presents the study of a correlation to predict ABS operating noise inside vehicle via HILS rig test. The regression equation in this paper was statistically drawn from using Minitab S/W, and based on that equation, the noise spectrum of vehicle interior was analogized.

• 한국수소및신에너지학회논문집
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• 제33권5호
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• pp.566-573
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• 2022

In this study, the mechanical properties of the polymer electrolyte membrane according to the temperature were studied. The test specimens of polymer electrolyte membrane were heat treated at 40℃, 60℃, 80℃, 100℃, and 120℃, and then the tensile tests were performed. As results of this study, the residual stress of the polymer electrolyte membrane was removes by the heat treatment and the elastic modulus decreased due to the decrease in internal energy. In addition, in the plastic region, the mechanical properties and crystallization rate of the polymer electrolyte membrane increased in proportion according to increase of the heat treatment temperature.