Ba-Ferrite를 이용한 자기 연마재 개발

김희남,송승기,정윤중,윤여권,김희원,조상원,심재환 한국안전학회 2003 한국안전학회지 Vol.18 No.2

The magnetic polishing is the useful method to finish some machinery fabrications by using magnetic power. This method is one of the precision techniques and has an aim for clean technology in the transportation of the pure gas in the clean pipes. The magnetic abrasive polishing method is not so common in the field of machine that it is not known to widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. Therefore, in this paper we deals with the development of the magnetic abrasive with the use of Ba-Ferrite. In this development, abrasive grain WA has been made by using the resin bond fabricated at low temperature. And magnetic abrasive powder was fabricated from the Ba-Ferrite which was crushed into 200 mesh. The XRD analysis result shows that only WA abrasive and Ba-Ferrite crystal peaks were detected, explaining that resin bond was not any more to contribute chemical reaction. From SEM analysis, we found that WA abrasive and Ba-Ferrite were strongly bonding with each other.

중국 국유기업에 대한 국경간 M&A 방안

金汝善,宋錫彦 濟州大學校 法과政策硏究所 1999 法과 政策 Vol.- No.5

멀티캐스트 ATM망에서 대체가상경로의 설정을 위한 유전 알고리듬

김여근,송원섭,곽재승 한국경영과학회 2000 韓國經營科學會誌 Vol.25 No.2

Multicasting is the simultaneous transmission of data to multiple destinations. In multicast ATM networks, the effect of failures on transmission links or nodes can be catastrophic, so that the issue of survivability is of great importance. However, little attention has been paid to the problem of multicast restoration. This paper presents an efficient heuristic technique for routing backup virtual paths in multicast networks with link failure. Genetic algorithm is employed here as a heuristic. In the application of genetic algorithm to the problem, a new genetic encoding and decoding method, and genetic operators are proposed in this paper. The other several heuristics are also presented in order to assess the performance of the proposed algorithm. Experimental results demonstrate that our algorithm is a promising approach to solving the problem.

무선 LAN RF 송수신 분석 및 시뮬레이션에 관한 연구

윤여송,김학선 한밭대학교 정보통신전문대학원 2003 정보통신전문대학원 논문집 Vol.1 No.1

본 논문에서는 IEEE 802.l1b와 IEEE 802.11a의 규격집으로부터 RF송수신 시스템의 설계를 위한 최소성능 요구 조건의 파라메터들을 제시하였으며,이 파라메터들로부터 RF송수신 시스템의 설계 과정에서 요구되어지는 최소성능 요구조건을 산출하였다. 그 산출된 값으로부터 RF송수신 시스템을 구성하기 위한 최적의 조건을 갖는 부품을 선정하여 agilent ADS로 시뮬레이션을 했다. 이러한 분석결과와 시뮬레이션 결과는 실제 무선 LAN 설계시 유용하게 사용될 수 있을 것이다. This paper presents design requirements of RF transceiver to achieve minimum required performance from specifications of IEEE 802.11b and IEEE 802.1la. The requirement and parameters will be used in the design process of IEEE 802.11 RF transceiver. After selecting components having optimal condition to develope RF trsnsceiver have been designed using an Agilent ADS(Advanced Design System). The results of analysis simulation can be used for a real wireless LAN design.

마비형 뇌성마비환자의 뇌파 및 임상양상

윤여훈,송홍기,김형철,이병철,이숙자 대한신경과학회 1996 대한신경과학회지 Vol.14 No.1

제2형 당뇨병 환자에서 체내 총항산화능 측정의 의의

윤여일,윤석기,김선규,김용현,남일송,차건영,황의원,김영선 순천향의학연구소 2001 Journal of Soonchunhyang Medical Science Vol.7 No.2

Background: The diabetic patients are at significantly increased risk of developing vascular disease. It's etiology may involve oxidative damage by free radiacals and protection againse such damage can be offered by antioxidants. We investigated that oxidative stress as assessed by measurement of total antioxidant status may play a role in development of diabetes mellitus. Method: We measured total antioxiant status using merchandised kit, glycated hemeglobin(HbA1c) in 46 type 2 diabetes mellitus patients and 50 healthy matched control subjects. Result: The total antioxidant status(TAS) was 2.10(±0.04) mmol/L in uncontrolled type 2 DM patients, 2.60(±0.03) in controlled type 2 DM patients and 2.70(±0.16) in healthy control subjects. TAS was significantly lower(P<0.05) in uncontrolled type 2 DM patients, but no significant association between in controlled type 2 DM patients and healthy control subjects. The TAS was 2.00(±0.17) mmol/L in complicated type 2 DM patients and 2.10(±0.29) uncomplicated type 2 DM patients. There was no significant associations between complicated type 2 DM patients and uncomplicated type 2 DM patients. Conclusion: Poor glycemic control is associated with reduced TAS in type 2 DM patients. TAS was thought indirect index that predict glycemic control of type 2 DM patients.

상악골 비구개관 낭종의 치험예

이상철,김여갑,류동목,송우식 경희대학교 1989 慶熙醫學 Vol.5 No.2

강산 및 강알칼리 음독에서 냉각 용액을 사용한 희석 요법과 중화 요법의 가능성

이중의,송형곤,김동훈,권운용,곽영호,서길준,윤여규 대한응급의학회 2001 대한응급의학회지 Vol.12 No.3

Background: There is no effective treatment modality for caustic agent ingestion. Dilution and neutralization are prohibited because of the risk of secondary thermal injury. This experiment is designed to evaluate the amount of dilution and neutralization heat and to gauge the applicability of dilution and neutralization therapy using cold solutions to suppress the peak temperature. Methods: This is an in-vitro chemical experiment. HCl, CH3COOH, NaOH, and NH4OH are selected as representatives of strong and weak acids and strong and weak alkali, respectively. 20℃, 11.6M, 5.8M, and 2.9M solutions of each acid and alkali are made and mixed using a magnetic stirrer at a room air temperature of 28℃. The peak temperature, the duration above 40℃, and the heat amount are measured or calculated. Results: When a 11.6M HCl or NaOH solution is diluted with same amount of water, 32 or 18cal. per mL of HCl or NaOH is produced, respectively. HCl produces a significant peak temperature, but NaOH does not. The lower the concentration, the lower the amount of heat production. 11.6M CH3COOH and NH4OH solutions don't produce dilution heat.11.6M and 5.8M solutions of all acids and alkali produce destructive neutralization heat. However, 2.9M solutions produce neutralization heat which might be controllable. When a 11.6M HCl or NaOH solution is neutralized with a -10℃ 2.9 M NaOH or HCl solution, respectively, the peak temperature produced is below 40℃ and seems to add little thermal damage to viable tissue. Conclusion: Dilution and neutralization with a cold solution in cases of strong acid or alkali ingestion is a promising method to avoid thermal injury.

파라콰트 중독에서의 항산화치료

권운용,조유환,송형곤,김명천,이중의,서길준,윤여규 대한응급의학회 2001 대한응급의학회지 Vol.12 No.4

Background: Paraquat causes severe tissue toxicity when ingested, but has no effective treatment modality. We have shown that high dose vitamin C has effective antioxidant activities against the paraquat intoxication in a previous animal experiment. This study was designed to evaluate the effect of antioxidant therapy with high dose vitamin C and vitamin E in human cases of paraquat intoxication. Methods: From August 1999 to August 2001, 19 paraquat intoxication patients who visited the emergency department of the Seoul National University Hospital and the Kyounghee University Hospital were enrolled to this study. They were devided into two groups, a control group(9 patients) and a study group(10 patients). The control group received only conservative managements including gastro-intestinal decontaminati-on. The study group received conservative managements plus the antioxidant therapy which was composed of vitamin C 24 gm/day intravenously and 20 gm/day orally, and vitamin E 1.6 gm/day orally. Results: In the study group, 5 of 10 patients(50%) survived, but all patients of the control group died(p=0.003). There were no significant differences in age, sex, and usage of gastric lavage and activated charcoal between the two groups. Difference in ingested amount of paraquat between the two groups could not be analyzed due to the inexact and subjective measuring methods based on patients' histories. Conclusion: Antioxidant therapy with high dose vitamin C and vitamin E is effective in vival rate in paraquat intoxicated patients.

間歇的 運動에 의한 脫水 및 水分攝取의 生理的 效果

朴哲浩,朴吉俊,李相于,金永明,朴贊熙,玄松子,呂南會,朴相甲,金榮俊 東亞大學校附設스포츠科學硏究所 1989 스포츠科學硏究論文集 Vol.7 No.-

This study aims at revealing the physiological responses of dehydration (DH) and rehydration (RH) in intermittent exercises at the work intensity of 70% HR max. First, with general student public, three times of exercise (each for 20 minutes) at the given work intensity were taken, with a break for 25 minutes respectively. Their heart rate, rectal temperature and plasma electrolyte concentration both DH and RH were measured. Second, in two groups of athletes and non-athletes, 9 rounds of exercise (for 100 minutes) and 8 breaks (for 60 minutes) were taken, with RH forced 10 times to compensate for the subjects' water loss. Their change in sweat loss and plasma electrolyte concentration as well as the IVDP(Intensive Voluntary dehydration Phenomenon) were experimented. The summary of this research follows. 1) Mean heart rate and rectal temperature in intermittent exercises were higher at DH than at RH, growing up at the increasing level of DH. 2) RH saw no change in the plasma concentration of Na+, K+ and Cl-, while DH observed a significant increase. 3) HCO₃made a significant decrease at DH before growing up. 4) Mg++ had no change, while Ca++ increased significantly at RH and DH. 5) Lactate showed an increase with significance at RH and DH, especially greater at DH. 6) Osmotic pressure increased meaningfully at DH. 7) Anion gap increased significantly at DH and RH. 8) On the other hand, when the forced RH was held, the group of athletes had greater sweat loss per body surface area than that of non-athletes. 9) The athletes' plasma concentration of Na+ and Cl- revealed a clear decrease. 10) There was seen no significant change in the plasma concentration of K+, Mg++ and Ca++ in both groups. 11) The IVDP occurred at the RH of 2.3ℓfor athletes and more than 2.5ℓfor no-athletes.