• Journal of Powder Materials
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• v.18 no.5
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• pp.456-462
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• 2011

Yttrium oxide is one of the most thermo-dynamically stable materials, so that it is generally used as a dispersoid in many kinds of dispersion strengthed alloys. In this study, a nickel-base superalloy is strengthened by dispersion of yttrium oxide particles. Elemental powders with the composition of Ni-22Cr-18Fe-9Mo were mechanically alloyed(M.A.) with 0.6 wt% $Y_2O_3$. The MA powders were then HIP(hot isotactic press)ed and hot rolled. Most oxide particles in Ni-22Cr-18Fe-9Mo base ODS alloy were found to be Y-Ti-O type. The oxide particles were uniformly dispersed in the matrix and also on the grain boundaries. Tensile test results show that the yield strength and ultimate tensile strength of ODS alloy specimens were 1.2~1.7 times higher than those of the conventional $Hastelloy^{TM}$ X(R), which has the same chemical compositions with ODS alloy specimens except the oxide particles.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1571-1581
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• 2016

A novel method is proposed to construct the voltage stability boundary of power system considering different Reactive Power Control Mode (RPCM) of Doubly-Fed Induction Generator (DFIG) Wind Power Plant (WPP). It can be used for reflecting the static stability status of grid operation with wind power penetration. The analytical derivation work of boundary search method can expound the mechanism and parameters relationship of different WPP RPCMs. In order to improve the load margin and find a practical method to assess the voltage security of power system, the approximate method of constructing voltage stability boundary and the critical points search algorithms under different RPCMs of DFIG WPP are explored, which can provide direct and effective reference data for operators.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2106-2107
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• 1998

This paper analyzes the sources of EMI noise, and Presents the noise reduction method using the modulation of switching frequency. Modulating the switching frequency makes the noise of side bands by shattering emission spectrum, and then can reduce the size of EMI filter at input line of power supply.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.05a
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• pp.132-139
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• 1993

석탄가스화 공정과 복합발전 사이클을 결합한 IGCC 발전 시스템은 기존의 석탄연소 발전방식에 비해 열효율이나 공해배출 문제 등에서 월등히 우수한 특성을 가지므로 차세대 발전개념으로 크게 각광받고 있다. 이러한 이유로 선진공업국들은 70년대 석유 파동이래 IGCC 기술을 중점 개발하여 왔고, 머지않아 상업화에 도달할 전망이다. 국내적으로도 전기수요량의 급격한 증가와 엄격한 환경규제 등의 현실적 요인으로 인해 IGCC 발전에 관심이 집중되고 있으며, 이와 더불어 우리실정에 맞는 IGCC 공정기술의 개발이 시급한 실정이다.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.10a
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• pp.255-258
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• 2005

닭고기의 함수율이 증가함에 따라 저장 5일의 6% 처리구에서 TBARS 값이 0.067, 8%, 0.082, 10%, 0.093 mgMA/kg으로 계속 증가하는 경향을 나타내었다. 육색에서 명도(L*), 황색도(b*)는 함수율에 따라 일정한 경향을 나타내지 않았다. 함수율에 따른 총 세균수는 저장 3일 6% 처리구에서 2.87, 8%, 2.93, 10%, 2.90 log CFU/$cm^2$로 처리 간에 큰 차이를 나타나지 않았다. 저장 5일에서 6% 처리구는 3.03, 8%, 3.01, 10%, 3.13 log CFU/$cm^2$로 10% 처리구에서 약간 증가하는 경향을 나타냈으나 함수율에 따라 큰 차이를 보이지 않았다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.9
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• pp.467-472
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• 2001

In conventional zero-current-switching(ZCS) PWM converters, zero-current turn-off for main switch without increasing voltage/current stresses is achieved at a fixed frequency. The switching loss, stress, and noise, however, can\`t be minimized because they adopt auxiliary switches turned off and main switches turned on under hard-switching condition. In this paper, new ZCS-PWM converters of which all switches are always operating with soft-switching condition are proposed. Therefore, the proposed ZCS-PWM converters are most suitable for systems requiring high-power density Breadboarded ZCS-PWM boost converters using power MOSFET are constructed to verify theoretical analysis.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.587-588
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• 2006

The stress corrosion cracking (SCC) susceptibility of Alloy 600 MA, Alloy 600 TT, Alloy 800, and Alloy 690 TT were investigated in a deaerated 0.01 M solution of sodium tetrathionate using reverse u-bend test samples at $340^{\circ}C$. The results showed that SCC occurred in all alloys, excluding Alloy 690 TT. The SCC susceptibility decreased with an increase in the chromium content of the alloys. The results of the deposits and spectra taken from an energy dispersive X-ray system confirmed the existence of a reduced sulfur causing SCC.

• Progress in Superconductivity and Cryogenics
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• v.6 no.3
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• pp.16-20
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• 2004

YB $a_2$C $u_3$$O_{7-x}$ (YBCO) films were deposited on (100) SrTi $O_3$ single crystal substrates by a metal organic chemical vapor deposition (MOCVD) system of hot-wall type using single liquid source. Under the condition of the mole ratio of Y(tmhd)$_3$:Ba(tmhd)$_2$:Cu(tmhd)$_2$= 1:2.1:2.9. the deposition pressure of 10 Torr. the MO source line speed of 15 cm/min. the Ar/ $O_2$ flow rate of 800/800 sccm. YBCO films were prepared at the deposition temperatures of 780∼89$0^{\circ}C$. In case of the YBCO films with 2.2 ${\mu}{\textrm}{m}$ thickness deposited for 6 minutes at 86$0^{\circ}C$. XRD pattern showed complete c-axis growth and SEM morphology showed dense and crack-free surface. The atomic ratios of Ba/Y and Cu/Ba in the film were 1.92 and 1.56. respectively. The deposition rate of the film was as high as 0.37 ${\mu}{\textrm}{m}$/min. The critical temperature ( $T_{c.zero}$) of the film was 87K. The critical current of the film was 104 A/cm-width. and the critical current density was 0.47 MA/$\textrm{cm}^2$. For the thinner film of 1.3 ${\mu}{\textrm}{m}$ thickness. the critical current density of 0.62 MA/$\textrm{cm}^2$ was obtained.d.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.4
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• pp.762-765
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• 2008

Ephedrae herba(Ma-huang) has been used to treat respiratory conditions for over 5,000 years. The early 1990s, the herbal ephedra and other products containing ephedrine began to be promoted as weight loss aids in United States. The objective of this study was to evaluate the acute toxicity of hebal ephedra in rats. SPF Sprague-Dawley male and female rats were administered orally with herbal ephedra extract of 2,500 mg/kg(low dosage group), and 5,000 mg/kg(high dosage group). We daily examined number of deaths, clinical signs, body weights and gross findings for 14 days. No dead animal and no significant changes of body weights were found during the experimental period. In addition, no differences were found between control and treated groups in clinical signs, hematology, serum biochemistry, and other findings. In conclusion, herbal ephedra extract did not show any toxic effects and oral LD50 value was over 5,000 mg/kg in SD rats.

• Journal of Sasang Constitutional Medicine
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• v.9 no.1
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• pp.213-243
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• 1997

After studying about the formative process and theory concerning So-Yang In(少陽人)'s prescriptions, Some principles were founded. Those were summarized as follows. 1. Lee Jae Ma(李濟馬) established the theory and remedy about the So Yang In's diseases, and the formation of So Yang In's prescriptions was based on those theories and remedies 2. As the emprical prescription of So Yang In's diseases, ten pre-scriptions of Discussion of Cold-Induced Disorder(傷寒論) and nine of Won Myung dynasty period(元明時代) were described in Dong Eui Su-Se Bo Won(東醫壽世保元), and I could confirm that the formation of So Yang In's presciptions was based on those emprical prescriptions. 3. The pathological characteristics of emprical prescriptions of So-Yang In's diseases in Discussion of Cold-Induced Disorder(傷寒論) were completely corresponded with the principle of So Yang In's diseases, and we could know that emprical presciptions of diseases that were the base of So Yang In's prescriptions were selected by the principle of So Yang In's diseases. 4. In the serious cases of So Yang In's diseases, So Yang In's pre-scriptions were mostly made up of tonifying and nourishing yin medicine(補陰藥物) that dirrectly rufill the damaged Eum Chung Zi Ki(陰淸之氣). According to the above results, it could be concluded that Lee Jae-Ma(李濟馬) made So Yang In's prescriptions with emprical pre scri-ptions that were based on the theory of So Yang In's diseases and concluded that So Yang In's prescriptions were made up of tonifying and nourishing yin medicine(補陰藥物) in the serious cases of diseases.