강구조용 내화도료의 기술 현황

변정식(Jeong Sik Byun) 한국강구조학회 2014 韓國鋼構造學會誌 Vol.26 No.5

신발제조업체의 접착제 사용에 따른 직접·간접폭로 근로자들의 복합유기용제 폭로량과 자각증상 비교

변정식,김정윤,조영채,김동현,Byun, Jeong-Sik,Kim, Jeong-Yun,Cho, Young-Chae,Kim, Dong-Hyun 한국산업보건학회 1995 한국산업보건학회지 Vol.5 No.1

This study was performed to find out the exposure level of mixed organic solvents, excretion of urinary hippuricacid and subjective symptoms according to the exposure of organic solvents of female workers who works on 5 shoes manufacturing industries in Taejon City from 24, september to 20, october 1993. The studied groups were divided into 3 groups that were consist of direct exposure group(48 workers), indirect exposure group(49 workers) and non-exposure group(68 workers) to the organic solvents. The exposure levels of toluene of direct exposure group which $89.86{\pm}56.20ppm$ had higher than that of indirect exposure group which had $40.23{\pm}47.21ppm$. In the exposure level of mixed organic solvent(R-value), direct exposure group was $2.84{\pm}1.53$ and exceeded approximatly 3 times the R-value. Whereas, indirect exposure group was not exceeded the R-value as $0.80{\pm}0.61$. In the excretion level of urinary hippuric acid, direct exposure group was $1.78{\pm}1.25g/l$, indirect exposure group was $1.22{\pm}0.93g/l$ and non-exposure group was $0.51{\pm}0.18g/l$ respectively. Therefore both direct exposure group and indirect exposure group were significantly higher than non-exposure group(P<0.01). In the correlation between toluene levels and urinary hippuric acid level, the direct exposure group had positive correlation(R=0.8309, P<0.01), also indirect exposure group had positive correlation(R=0.5859, P<0.05) and also in the correlation between the R value of mixed organic solvents and the urinary hippuric acid levels, the direct exposure group had positive correlation(R=0.4492, P<0.05), and indirect exposure group had ositive correlation(R=0.7911, P<0.01). In the complain rates of the worker's subjective symptoms at work, both direct exposure group and indirect exposure group were higher than non-exposure group(P<0.05, P<0.01). But the sujective symptoms of "floating sensation" of direct exposure group had significantly higher than indirect exposure group. In the percent of subjective symptoms complaints during the worker's daily life, both direct exposure group and indirect exposure group had generally more statistical significance than nonexposure group(P<0.01), direct exposure group had not statistical significant difference from indirect exposure group. As the results mentioned above, it has been analysed that the indirect at the adjacent manufaturing process are exposed to the considerable amount of solvent. Therefore, I think that there should be the betterment of surrounding through the complete working environment management to the occurrence source of the organic solvent, the changes of health management system to the indirect-exposed workers, and the systematic management of the special medical examination and the like.

네트워크 단절 개선을 위한 적응적 전달자 노드검색 기법

홍원기(Won-Kee Hong),변정식(Jeong-Sik Byun) 한국산업정보학회 2009 한국산업정보학회논문지 Vol.14 No.3

본 논문은 VANET에서 노드의 높은 이동성으로 인해 문제 되고 있는 네트워크 단절 문제를 개선하기 위한 네트워크 노드 검색 기법을 제안한다. VANET은 인프라의 도움 없이 차량 간 무선 통신을 기반으로 하는 다중 홉 방식의 애드혹 네트워크이며, 이는 기존 MANET과 매우 유사하다. 그러나 VANET은 고속의 이동성, 높은 노드 밀도, 잦은 토폴로지 변화 등의 특징으로 인해 네트워크 단절이 빈번하게 발생하며 네트워크 부하가 증가하는 문제를 가진다. 본 논문에서는 이러한 네트워크 단절을 해결하기 위해 적응형 전달노드 검색 알고리즘을 제안한다. 제안하는 프로토콜은 브로드캐스팅을 통해 네트워크 단절 발생 시에만 선택적으로 위험지역 외의 영역에서 노드를 재 검색함으로써 네트워크 단절과 네트워크 부하를 줄여줄 수 있다. 실험 결과 제안하는 프로토콜은 기존 방식에 비해 21.2%~39.9%의 네트워크 단절 개선을 보였으며, 응급 메시지 수신율에서는 22.3%~41.9% 향상을 가져왔다. We propose a network node search scheme to address the network fragmentation due to high node mobility in the VANET. VANET is very similar to MANET in that a multi-hop ad-hoc network is configured by wireless communication between vehicles without any network infrastructure. However, high speed mobility, high node density, and frequent topology change induce frequent network fragmentation so that overall network traffic can be increased. In this paper, new broadcasting protocol called an adaptive relay node search protocol is proposed to decrease the network fragmentation. It reduces the network fragmentation and network traffic by researching nodes outside the dangerous area only in case of network fragmentation. Simulation results show that the proposed protocol decreases network fragmentation by up to 39.9% and increase informed rate by up to 41.9% compared to the existing broadcasting protocol.

랫트의 생체내 카드뮴 단독투여 및 카드뮴과 셀레늄 병용투여에 따른 필수원소의 변화

김동현,변정식,조영채,이범식,김광환,김정윤 忠南大學校 環境問題硏究所 1995 環境硏究 Vol.13 No.-

This study was performed to find out the changes of essential elements as Cu, Fe, Zn, and Ca in blood, liver, kidney and testis of rats. The experimental rats were divided into 4 groups that were consisted of control group(groupⅠ), 3.0㎎Cd/kg group(groupⅡ), 3.0㎎Cd +1.0㎎Se/kg group(groupⅢ) and 3.0mgCd+2.5mgSe/kg group(groupⅣ). Each group was intraperitoneal injection with difference dose of cadmium and selenium such as 3.0mgCd/kg, 3.0mgCd+1.0mgSe/kg and 3.0mgCd+2.5mgSe/kg. Rats were killed at the time of 3 day and 28 day, and Cd, Se, Cu, Zn and Ca concentration in several organs were determined by Atomic Absorption Spectrophotometry and inductively Coupled Plasma. Cadmium content in blood, liver, kidney and testis were significantly increased in the Cd alone injection group than Cd mixed with selenium injection groups. But, copper content were not significantly differences in control and each experimental group. Iron content were significantly increased in the Cd alone injection group than others groups. Zinc and calcium content were significantly decreased in the Cd alone injection group than other groups. On the other hand the essential element content in Cd mixed with selenium injection group were almost equaled with those of control group than Cd alone injection group.

모 주물공장 근로자의 작업공정별 분진폭로량, 자각증상 및 건강진단판정 비교

이범식,조영채,변정식,김동현,원선혜,김정윤 忠南大學校 環境問題硏究所 1995 環境硏究 Vol.13 No.-

The relationship among dust exposure dose, special health diagnosis results and subjective symptom questionaire survey for 109 casting foundry workers supervised by a local laber office has been studied from august to october 1993. Subjective symptom, dust exposure dose and health examination evaluation of respective working processes have been analized and concluded as follows; 1. Metal fume concentration in melting process measured 3.21±1.46㎎/㎥ is under threshould limit value(TLV;5.0㎎/㎥), casting sand dust measured in molding and desanding process is 5.8 ±3.41㎎/㎥ and 9.69 ±2.64㎎/㎥ which is 3-5 times higher than TLV(2.0㎎/㎥), metal fume, welding fume and metal dust in finishing process measured 9.34 ±1.32, 13.73 ±16.97 and 10.17 ±3.50㎎/㎥ respectively, which are also 2-3 times higher than TLV(5.0㎎/㎥). 2. The complain rate subjective symptoms appeal evaluated for finishing process are 35.9%, 46.2%, 27.2% and 42.2% for eye smptoms, respiractory, skin, general symptom respectively and the rates above express the highest values and the complain rates for melting process are 24.4%, 37.5% and 35.7% for eye smptoms, respiratory and mental system respectively and for molding and desanding it is 24.3%. 3. Perceived occupational disease rate is found 0.9% with are out of 109 worker surveyed who have been exposed in metal fume of finishing process. 4. 33.0% of workers surved are found to require close examination, the worker of hepatopathy suspected are 21.4% which is the highest and 3.7% for circulatory disturbance suspected. 5. The statistically significant variables in general chracteristics that affect health examination evaluation are smoking(P<0.001), respirator put-on (P<0.05) and working career(P<0.05). 6. Cough(P<0.001), "headache"(P<0.05) and "easily skin exchange by slight stimulation" (P<0.05) are statistically significant to the subjective symptom variables affect health examination evaluation.

궤양성 대장염 환자 및 위절제술을 받은 환자의 소장 통과시간

김태호,이동호,김유선,송인성,정현채,최규완,김정룡,이국래,장동경,정준오,변정식 대한소화기학회 1998 대한소화기학회지 Vol.31 No.4

Background/Aims: Small bowel transit time (orocecal transit time) is an important parameter of intestinal function. The lactulose hydrogen breath test is a relatively simple, sensitive and noninvasive method for measuring orocecal transit time. The small bowel transit time is known to be influenced by many factors such as psychological stress and menstrual cycle. However, it is not obvious how resection or diseases of the stomach and colon affect on small bowel transit time. We compared orocecal transit time of patients with ulcerative colitis and who had received gastrectomy with that of healthy controls. Methods: We investigated orocecal transit time of 18 healthy persons, 12 patients who had received gastrectomy, 11 patients with active ulcerative colitis and 14 patients with inactive ulcerative colitis. After overnight fasting, lactulose 13 g with water 100 cc was ingested. Then, end-expiratory gas was collected every 15 minutes for 4 hours, The amount of hydrogen in the collected gas samples was measured by Trace Gas Analyzer (Quintron^(R)), Results: For normal Korean adults, the mean of orocecal transit time was 95±18.5 minutes (range: 60-135). The orocecal transit time in patients who had received gastrectomy and patients with ulcerative colitis is longer than that of healthy controls (p$lt;0.01). No statistical difference was found between patients with active and inactive ulcerative colitis. However, the orocecal transit time in active stage patients was prolonged by 35 minutes. Conclusions: The lactulose hydrogen breath test is a valuable rnethod to assess orocecal transit time in patients with variable gastrointestinal diseases. The underlying mechanism for these results are unclear, but it is suggested that some regulating factors of gastrointestinal motility are changed due to gastrectomy and inflammation of the colon. Further investigation is needed to elucidate the mechanism of the change of orocecal transit time.