코로나 대전된 복합절연재료의 표면상태가 전위감소에 미치는 영향

황명환,정재희,조한구,송진호,이덕출 한국산업안전학회 1997 한국안전학회지 Vol.12 No.2

Especially, Fiber glass Reinforced Plastics(FRP) is the best composite insulating material which has been so far. Therefore, it's worthy of notice to investigate on the corona electrified composite insulating material by surface condition. And then some other materials will be focussed on. In this study, charge decay were measured with charging-time and grid voltage on FRP composite material surface in order to analyze the mechanism. As a result we have studied that the way of the composite glass fiber(GF) and Polymer and the condition of the contaminated surface was different. In case of the GF is mixed with vertical, charge decay speed is fast because the charge is easily leaked. On the other hand, the surface charge decay speed is depend on conductive or insulated of the contaminant.

방전 플라스마에 의한 CFC-12(CCl2F2)의 분해

황명환,우인성,조정국,강현춘,안형환,이한섭,강안수 한국산업안전학회 1999 한국안전학회지 Vol.14 No.3

Decomposition efficiency, power consumption, and applied voltage of CFC(Chlorofluorocarbon) were investigated by SPCY(surface induced discharge plasma chemical processing) reactor to obtain optimum process variables and maximum decomposition efficiencies. Decomposition efficiency of CFC-12 with various electric frequencies(5∼50㎑). flow rates (100∼1,000mL/min), initial concentrations(100∼1,000ppm), electrode materials(W, Cu. Al), electrode thickness(1, 2, 3mm) and reference gases(N₂, O₂, air) were measured and the products were analyzed with FT-IR. Experimental results showed that at the frequency of 10kHz, the highest decomposition efficiency of 92.7% for CFC-12 were observed at the power consumptions of 29.6W, respectively, and that decomposition efficiency decreased with increasing frequency above 20㎑ and decomposition efficiency per unit power were 3.13%/W for CFC-12. Decomposition efficiency was increased with increasing residence times and with decreasing initial concentration of pollutants. Decomposition efficiency was increased with increasing thickness of discharge electrode and the highest decomposition efficiency was obtained for the electrode diameter of 3mm. As the electrode material, decomposition efficiency was in order that tungsten(W), copper(Cu), aluminum (Al).

화재완화를 위한 소듐 루프 건물의 구획화

김병호,권상운,정경채,김광락,황성태 한국산업안전학회 1998 한국안전학회지 Vol.13 No.3

Analysis on the study for the sodium fire mitigation was carried out using the CONTAIN-LMR code. Sodium loop building was partitioned into the many cells, in which the safety venting systems were installed for the purpose of improving the sodium fire safety and minimizing its effect on the sodium loop building. The effects of sodium fire on sodium loop building partitioned into the many cells and not partitioned were investigated. The peak pressure and temperature of each cell accompanied by sodium fire in sodium loop building partitioned were lower than those of sodium loop building not partitioned. In the case of partitioning sodium loop building, the pressures, temperatures and aerosols into cells were transferred through propagation path of CONTAIN-LMR sodium fire model simulated by this study, and the effect of sodium spray fire on sodium loop building was mitigated by partitioning building. In addition, the excessive rise of pressure into cells was prevented by installing the over-pressure exhaust valve and under-pressure exhaust valve on the flow path between cells.

SbI3 를 첨가한 33.3 % Bi2Te3-66.7 % Sb2Te3 열전반도체의 전기적특성과 열전특성

현도빈,황종승,심재동,오태성,황창원 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.2

The temperature dependences of the electrical and thermoelectric properties of the SbI₃-doped 33.3% Bi₂Te₃66.7% Sb₂Te₃ single crystals have been measured at temperatures ranging from 77K to 600K. The scattering parameter of the 33.3 Bi₂Te₃-66.7% Sb₂Te₃ single crystals was determined as s = 0. With increasing the amount of SbI₃ dopant, the hole concentration of the 33.3% Bi₂Te₃-66,7% Sb₂Te₃ single crystal is decreased, resulting in the increment of the Seebeck coefficient and electrical resistivity, and the temperature for the maximum figure-of-merit shifted to lower temperature. A maximum figure-of-merit of 2.3×10^(-3)/K was obtained for 0.3 wt% SbI₃-doped specimen. It has been revealed that. the addition of SbI₃ as a donor dopant is useful in controlling the hole concentration of p-type 33.3% Bi₂Te₃ 66.7% Sb₂Te₃ alloy system.

제왕절개수술에서 저혈압 예방을 위한 수액의 비교 관찰 : 제 1 보:척수마취

심재철,김완식,박동호,황영희,김흥대,김지영,차영덕,서병태 대한마취과학회 1982 Korean Journal of Anesthesiology Vol.15 No.3

Rheomacrodex-D 10% W/V in dextrose (500 ml) was prophylactically infused before anesthesia over 15 to 20 minutes to prevent hypotension during spinal anesthesia in 20 patients undergoing elective Casarean section. Apgar scores and the incidence and severity of hypotension were compared to results obtained in 20 patients who were given 500 ml of Hartmann's solution. The results were as follows; 1) Mean arterial pressure decreased up to 20 torr from control values in patients hydrated with Hartman's solution and also changed significantly in patients given Rheomacrodex-D (p<0.05). 2) The incidence and severity of hypotension at 10 minutes, and 15 minutes, and 15 minutes after spinal anesthesia (p<0.05) was significantly less in patients given Rheomacrodex-D than in patients hydrated with Hartmann's solution 3) The Apgar scores, both at 1 minute and 5 minutes, were significantly higher (p<0.05, p<0.005) in infants born of mothers given Rheomacrodex-D than in infants whose mothers were given Hartmann's solution. 4) The cases of hypotension defined as a descrease in systolic arterial pressure lower than 100 torr or a decrease in mean arterial pressure to 25% from control values were 12 cases in 20 patients hydrated with Hartmann's solution and 6 cases in 20 patients given Rheomacrodex-D.

급성췌장염에 의한 췌장가성남종에서 내시경적 배액술후 발생한 췌장가성남종과 십이지장 및 대장에 발생한 내부 췌장루 1예

김연수,이문성,김진오,조영덕,이영홍,봉형근,조주영,이준성,심찬섭,황성규,전기원,변재호,장재영 대한소화기학회 1996 대한소화기학회지 Vol.28 No.1

진동형 분진 최소착화에너지측정장치에서 분진 응집현상이 미치는 영향

정재희,최충석,목연수,최광석,황명환,우인성,Yamaguma, M.,Kodama, T.,Cheung, W.L. 한국산업안전학회 1999 한국안전학회지 Vol.14 No.3

It is widely recognized that Hartmann tube for measuring the minimum ignition energy(MIE) of powder. But It requires long time and operational skills for measuring. As a variety of new fine powders are being produced day by day in industry, Japen has been developing a measurement system which employs a new method to create a dust/air mixture in a miniature combustion box. In this system, by vibration, the powder is successively fed downward through a hopper made up of metal mesh, and then it is formed into a thin, certain-like, dust/air mixture. With this new apparatus, three types of powder-Lycopodium, Anthraquinone, and Polyacrylonitrile-were tested and the data of MIE were compared with those of a conventional apparatus (the Hartmann tube). Two of them agreed satisfactory, but the other, Anthraquinone, showed quite different values. It is guessed that the agglomerations of the powder particles appear because of particle shapes, static-charge and humidity.

성인에서 발견된 십이지장 막양구조

박경규,박형근,김연수,이문성,김진오,조영덕,이영홍,봉형근,조주영,이준성,심찬섭,황성규,함정식,장재영,권귀향 대한내과학회 1997 대한내과학회지 Vol.53 No.2

Duodenal obstruction is the third leading cause of intrinsic obstruction of the alimentary tract in the newborn, the other causes are imperforate anus and esophageal atresia. If the obstruction is incomplete, as with a fenestrated duodenal membrane, the presentation of the symptoms may be delayed and the diagnosis overlooked. And so they are rarely diagnosed in the adult. Diagnosis can be made by contrast duodenography but is more definitive with endoscopy. This is the first case report of a 21-year-old female with duodenal membrane, associated with incomplete rotation of intestine and uterus bicornis, diagnosed by hypotonic duodenography and endoscopy, preoperatively, and successfully treated with duodenoduodenostomy.

병렬처리 시스템에서의 효율적인 동기최적화 기법에 관한 연구

황종선,김병두,박두순 한국생산성학회 1992 生産性論集 Vol.6 No.1

This paper discusses an effective synchronization algorithm. It is different from the existing synchronization methods by inserting appropriate synchronization instructions between statements according to different kinds of data dependences. The overhead caused by too many synchronization instructions in a loop can be a critical problem. Synchronization optimization is a method which discriminates and eliminates the redundant synchronization instructions in a loop. In this paper, a new synchronization optimization algorithm - ICPG (Improved Controlled Path Graph) - is developed, and the algorithm is extended to the case of nested loops. In case of nested loops, the existing methods were not safe because of the incomplete management in hyper-rectangle areas, etc. But, the errorneous methods are completely corrected in this paper. Finally, performance analysis using simulation on the UNIX operating system is carried out. It is shown that the ICPG algorithm is much more effective than the existing methods.

Fabrication of ex situ processed MgB₂ wires using nano carbon doped powder

Lee, C.M.,Park, J.H.,Hwang, S.M.,Lim, J.H.,Joo, J.,Kang, W.N.,Kim, C.J. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15

We fabricated ex situ MgB<SUB>2</SUB> wires using C-doped MgB<SUB>2</SUB> powder as a precursor in order to improve the core density of the wires and their C doping content. The C-doped powder was prepared with Mg, B, and nano carbon (NC) powders by the in situ technique and then MgB<SUB>2-x</SUB>C<SUB>x</SUB> (x=0, 0.01, and 0.03) wires were fabricated by the ex situ technique using the powder-in-tube method. The phase formation, lattice change, and microstructure were characterized and correlated with the T<SUB>c</SUB> and J<SUB>c</SUB> variations. We observed that the ex situ wire had a higher core density than the in situ wire, however its morphology consisted of agglomerated particles, indicating that sintering and grain growth did not occur completely, even though the sintering was conducted at high temperature (1000<SUP>o</SUP>C). As the C content increased, T<SUB>c</SUB> decreased, while the decrease of J<SUB>c</SUB> with increasing magnetic field became smaller. The J<SUB>c</SUB> of MgB<SUB>1.97</SUB>C<SUB>0.03</SUB> wire made by the ex situ technique was 3.34kA/cm<SUP>2</SUP> at 6.6T and 5K which is comparable to that of the in situ wire (4.81kA/cm<SUP>2</SUP> at 6.6T and 5K).