분사연마작업에서 발생되는 호흡성 및 총 에어로졸에 대한 개인시료포집방법간의 비교연구

홍대용,백종민,DaleStephenson,TerrySpear,MarieSeymour 한국산업보건학회 2003 한국산업보건학회지 Vol.13 No.2

행 기반 저장소에서 컬럼 접근 최적화

홍대용,이상원 한국정보과학회 2013 데이타베이스 연구 Vol.29 No.2

In order to access a column value in traditional row-store DBMSs, its starting position should be identified. Even in most modern row-wise DBMS such as Oracle and PostgreSQL, all the preceding columns in a tuple to which a column under access belongs need to be scanned in order to calculate the offset of the column. With this approach, there exist two performance problems,especially when columns to be accessed are physically located at the rear part of long tuples: 1)many CPU instructions are required to calculate the offset and 2) excessive CPU cache misses are encountered from accessing other columns irrelevant to the query. In this paper, we propose an optimization technique for accessing columns in row-store DBMSs and describe our implementation using an open source DBMS, PostgreSQL. Specifically, in our scheme, the offset of each column is pre-calculated and stored in an array of column offset in the tuple header, and from the offset information, a column data can be accessed only by obtaining its offset from the array. According to our simple experiment using a table from TPC-H benchmark, our scheme can outperform the existing one by up to 50 percent. And this remarkable performance improvement can be explained by the reduced CPU instructions used in calculating the column offset, and increased cache efficiency by reducing main memory accesses while scanning the tuple. To make the calculation simpler, proposed structure would increase size of the table, but improves cache efficiency when scanned pages are not cached in CPU. Therefore, it will be effective to systems that queries are intensively executed on specific hot-data or main memory DBMS. 전통적인 행 기반 데이터베이스에서 특정 컬럼에 접근하기 위해서는 컬럼의 위치를 나타내는 오프셋을 구해야한다. Oracle이나 PostgreSQL과 같은 DBMS는 질의에 의해 요청된 컬럼의 오프셋을 구하기 위하여 선행하는 컬럼들의 길이를 더한다. 이때 선행하는 컬럼들의 길이는 컬럼의 헤더로부터 구할 수 있다. 이러한 방식은 적은 수의컬럼에 접근할 때에도 필요한 컬럼 뿐 아니라 다른 컬럼에 접근하면서 많은 CPU 명령어 수행을 필요로 하며, 튜플길이가 긴 경우 불필요한 데이터 캐시 미스를 유발한다. 본 논문에서는 행 기반 저장소에서의 컬럼 접근 최적화기법을 제안하고, 이를 오픈소스 DBMS PostgreSQL를 사용해서 구현하였다. 구체적으로, 컬럼 접근 최적화를 위해각 컬럼들의 오프셋 위치를 미리 계산해서, 튜플 헤더 부분에 배열 구조로 위치시키고 컬럼 접근시 오프셋 값을이용해서 해당 컬럼 데이터를 바로 접근하게 하였다. TPC-H 벤치마크의 특정 테이블을 사용한 실험 결과, 제안기법은 기존 방식에 비해 최대 50%까지 성능 개선을 확인하였다. 이러한 성능 향상은 컬럼 오프셋 위치를 구하는데필요한 CPU 명령어 감소와, 메모리 접근 횟수를 줄임으로써 캐시 효율이 증가하는 것에 기인한다. 제안한 방식은단순한 계산을 위하여 테이블의 크기를 증가시키지만 탐색중인 페이지가 CPU에 캐시 되지 않은 경우 캐시 효율증가를 기대할 수 있다. 따라서 특정 Hot data가 자주 사용되는 환경이나 메인 메모리 DB에서 효과 적일 것이다.

^(32)P-postlabelling法을 이용한 有機溶劑 작업장 근로자의 遺傳毒性 評價

홍대용,김장락,이장호,문중갑,이한우,김동일,박성학,정주화,이홍근 한국환경독성학회 1994 환경독성보건학회지 Vol.9 No.1

To evaluate the genotoxicities of workers exposed to glue and glue cleaning solution, ambient air monitoring of working place, animal study and human monitoring were carried out. By GC-MS analysis, air samples collected from shoesmaking plant were found to be toluene, xylene, cyclohexane, n-hexane, methyl ethyl ketone, trichloroethylene, butylacetate, isopropyl alcohol. Glue and glue cleaning solution from shoesmaking plant were applicated topically to the CD-1 mice. DNA was isolated from skin 24 hr following the application and analysed for DNA-adducts using the nuclease P₁ version of ^(32)P-postlabelling assay. RAL (Relative Adduct Labelling, adducts/10^(8) nucleotides) was significantly increased in a dose-dependent manner in the glue cleaning solution treated mice skin. Peripheral blood DNA-adducts of workers exposed to glue and glue cleaning solution were also analysed by the same method, but there were not significant differences in the peripheral blood DNA-adducts level between exposed and control workers. In addition, glue cleaning solution from shoes factory was evaluated for mutagenicity in the Salmonella plate incorporation assay using strains TA 100 and TA 1535 in the presence and absence of Arochlor 1254-induced rat liver S_(9). There was evident mutagenicity for cleaning solution in TA 100 regardless of S_(9), but TA 1535 showed positive only in the absence of S_(9) when predicted by Stead model of mutagenicity prediction (p=0.0000). The urine concentrates from workers and controls were also assayed for mutagenicity towards strain TA 100 of Salmonella typhimurium in the presence of S_(9) using Kado's microsuspension assay, but their mutagenic activities were not found to be significant. These data suggest that shoesmaking workers are exposed to genotoxic compounds and need to be monitored by testing the mutagenicity of human urines. However, ^(32)P postlabelling application requires further validation for the routine monitoring of human exposure.

運動과 아나볼릭스테로이드(Testex)가 Rat에 있어서 水泳時 持久力 및 여러 臟器에 미치는 影響

洪大容,鄭善太,崔鶴曦 대한보건협회 1986 대한보건연구 Vol.12 No.2

The use of anabolic steroids to increase muscle mass has become widespread despite International Olympic Committee (IOC) gave order not to use these potent drugs to enhance performance. The present study was undertaken to determine the effects of 4 weeks administration of Testex (testosterone propionate) upon levels of performance, organ weights in adult albino rats. Animals were injected daily(I.M) with a placebo (corn oil), low dose(.5mg/kg) or high dose(5mg/kg) of Testex and subjected 5 days/week to one of 2 treatments: sedentary housing, or forced-swimming. At final day all animals allowed to swim, until to death to check the endurance time and rapidly extracted internal organs(heart, liver, kidney and testes) after being drowned to weigh the weights. Heart, weights increased in exercised rats. Heart muscle was significantly affected in rats injected low doses in both sedentary and swimming groups. Endurance time was prolonged by exercise significantly. The effect of Textex to endurance time was significant in sedentary group but not in exercised group.

당대 (當代) 교유인들의 (交游人) 기록

홍대용,성대중,노경,박준원,이덕무,유득공,박제가,이서구,남공철,한석호,한재렴 한국한문학회 1988 韓國漢文學硏究 Vol.11 No.-

經路分析을 通한 健康信念模型에 關한 硏究

洪大容,최학의,鄭善太 慶尙大學校 1985 論文集 Vol.24 No.1

A theoretical framework of "Health Belief Model" were used to examine the factors which are assumed to impact upon health belief and preventive action. The survey was carried out from Oct. 1 to 30, 1984 with a representative sample of middle and high school students (N=1.868) by structured questionaire. The results of zero-order correlation analysis, multiple regression analysis and path analysis were as follows : 1) The simple correlation analysis reveals that the variables affecting the preventive action are school grade(p<0.05), sex(p<0.05), area (p, 0.05), parent's education level (p<0.05). The results indicated that the higher school grade is, the more the preventive action is and urban area shows higher preventive action than rural area. Girl students showed higher preventive action than boy students. Parent's education level was proved to be effective on the preventive action, too. But pre-recommendation of preventive action showed non significant relationship with the preventive action, therefore it was not proved that the cue to action variables are important to explain health behavior. 2) According to the results obtained by multiple regression analysis, the threat about disease is affected by sex (β=0.1913), area (β=-0.0801), economic level (β=-0.0480) and academic a chievement (β=-0.0648) at very significant level (p<0.001). The perceived benefits of preventive action, considered to be as positive health belief variable turns out to be affected by parent's education level (β=0.0062), economic level (β=0.0661), academic achievement (f=-0.0330) and the knowledge about disease (β=0.1075) at very significant level (p<0.001). In this results, we can find the difference between positive health belief and negative health belief. On the contrary to the threat about disease, education was doing a very important role on the perceived benefits of preventive action. 3) The factors affecting the Preventive action were Proved to be school grade (β=-0.1138), sex (β=-0.0839), area (β=0.0866), economic level (β=-0.0438), the threat about disease (β=0.0439) and the Perceived benefits of preventive action (β=0.0424) (p<0.001). In point, we can find the preventive action is affected more by the threat about disease than by the perceived benefits of preventive action. Therefore it can be stressed that the promotion of the health behavioral change can be achieved effectively by negative health belief than by positive health belief in a city or rural area except metropolitan city. So we can say the different approaching method is needed according to the circumstances of each area to attain the desired end. 4) The path analysis shows the same results of the multiple regression analysis. Among the variables (individual characteristic variables, cue to action variable, health belief variables), only sex and health belief variables are affected more by causal effect than by non-causal effect. And the hypothesis, the health behavior are affected by health belief, is proved to be ture.

실내 NO₂농도 및 NO₂개인 폭로량에 영향을 미치는 요인에 관한 연구 : Centering University and Personnel in Pusan 부산지역 모 대학교 및 교직원과 학생을 대상으로

김동일,김준연,홍대용 동아대학교 의과대학 부설 산업의학연구소 1992 산업의학연구소 논총 Vol.- No.1

부산의 도심지역에 위치한 모 대학교 및 교직원과 학생을 대상으로 1990년 2월 1일부터 3월 31일까지 NO₂개인 폭로량과 그들이 활동하는 강의실, 연구실, 실험실, 사무실 등의 실내 NO₂농도를 측정하였다. 동시에 NO₂농도에 영향을 미칠 것으로 기대되는 난방형태, 난방기 가동시간, 환기형태, 조사장소의 면적, 연료소비량, 흡연습관 등의 변수에 대한 조사를 실시하여 NO₂에 대한 영향정도를 평가하기 위해 영향인자를 독립변수로 하여 다분류 해석법을 시행하였다. 본 연구에서 얻어진 결과는 다음과 같다. 1. 실내 NO₂총 평균농도는 27.5±20.2 ppb 였으며, 각 건물마다 NO₂평균농도는 차이가 있었다 (p<0.05). 2. 난방기를 가동하는 장소에서 가동하지 않는 장소보다 NO₂농도가 높았으며, 발열식 보다 대류식 난방기를 사용하는 곳에서 NO₂농도가 더욱 높았다(p<0.05). 3. 창문을 열어서 환기를 하는 것이 실내 NO₂농도를 낮추는 데 효과가 가장 컸다. 4. 실내 NO₂개인 폭로량은 평균 57.8±41.0 ppb 였으며, 건물의 위치에 따라 NO₂개인 폭로량에 차이가 있다(p<0.05). 5. 교직원이 학생보다 NO₂개인 폭로량이 많았다(p<0.05). 6. 난방기를 가동하는 곳에서 근무하는 사람들은 가동하지 않는 곳에서 근무하는 사람들보다 NO₂개인 폭로량이 많았다(p<0.05). 7. 난방기 가까이에서 근무는 사람은 난방기에서 떨어진 사람보다 NO₂개인 폭로량이 많았다(p<0.05). 8.실내 NO₂에 영향을 미치는 정도는 각 건물간 영향이 가장 컸으며, 다음이 난방형 형태, 환기형태 순이었다. 9. NO₂개인 폭로량에 영향을 미치는 정도는 각 건물간 영향이 가장 컸으며, 다음이 난방형태, 난방기로부터 거리 순이었다. 10. 겨울철 실내에서 난방기를 가동할 때에는 환기(특히 창문을 이용)를 하는 것이 실내 NO₂농도를 낮추는 데 효과적이며, 난방기로부터 되도록 떨어져 생활하는 것이 NO₂개인 폭로량을 줄이는 데 효과가 큰 것으로 나타났다. Indoor air quality is very important to human wellbeing because people spend much of their time indoors, in some cases indoor air quality is remarkably different from that of outdoor. Many energy conservation strategies for residences involve reducing house air exchange rates. Reducing the air exchange rate of house can cause an increase in pollutant levels if there is an indoor pollution source. Recently nitrogen dioxide( NO₂) has been regarded as one of the important indoor air pollutants. In this study, indoor NO₂levels were measured to provide the fundamental data for evaluation and control on the health effect relevant to NO₂levels. The levels of NO₂were measured by the Palmes method on 279 subjects in a university located in Pusan city from February to March 1990. The results of the study were summarized as follows: 1. The mean indoor NO₂level was 27.5±20.2 ppb. 2. Personal NO₂exposure level was 57.8±41.0 ppb. 3. The mean indoor NO₂level was significantly higher at room with heater than without heater and significantly lower at vented room than in unvented room. 4. The personal NO₂exposure level was significantly higher at group with heater than without heater. 5. The factors affecting indoor NO₂concentration and personal exposure levels were location(by building), heating facility, mode of ventilation, residents(by building), distance from heater by the multiple classification analysis. Therefore, it is concluded that artificial ventilation and distance away from heater were effective means for reducing indoor NO₂levels and personal NO₂exposure levels.

일부 크롬 폭로 근로자들에 있어서 변이원성 지표로서의 소핵검사

윤형렬,김장락,홍대용 大韓産業醫學會 1993 대한직업환경의학회지 Vol.5 No.1

This study was conducted to investigate the possibility of utilizing micronucleus test for buccal mucosa and blood lymphocyte as an indicator for the evaluation of chromium mutagenicity in workers(n=40) exposed to chromium trioxide(CrO₃) and controls(n=40) in Pusan and Changwon cities form April 1 to August 30, 1992. Urine chromium concentration was measured by atomic absorption spectrophotometer. Self-recorded questionnaire were used to collect information on the relevant characteristics of the study subjects. The results were as follows. 1. The mean frequencies of micronucleus in buccal mucosa, blood lymphocytes and average urine chromium concentration of chromium platers were significantly higher than those for controls(p<0.01). 2. The mean frequencies of micronucleus in buccal mucosa and blood lymphocyte of chromium platers by smoking habit were significantly higher than those of controls(p<0.01). However, the difference of mean frequencies of micronucleus between smokers and non-smokers were not statistically significant(p>0.05). 3. The frequencies of micronucleus in buccal mucosa and blood lymphocyte were highly correlated(r=0.7706). Some of the other variables were also correlated, for example, urine Cr concentrations and frequencies of micronucleus in blood lymphocyte(r=0.7259), urine Cr concentrations and frequencies of micronucleus in buccal mucosa(r=0.6247), age and work duration(r=0.4032), work duration and frequencies of micronucleus in buccal mucosa(r=0.3603), age and frequencies of micronucleus in blood lymphocyte(r=0.3260), work duration and frequencies of micronucleus in blood lymphocyte(r=0.3231), age and frequencies of micronucleus in buccal mucosa(r=0.2760). 4. According to the results of multiple classification analysis, frequencies of micronucleus in buccal mucosa were statistically associated with occupation and work duration, frequencies of micronucleus in blood lymphocyte associated with occupation and work duration, and urine Cr concentrations associated with occupation. The results suggested that micronucleus test in buccal mucosa and blood lymphocyte could be used as a biological indicator for evaluating toxic effects of chromium.

산업역학에서 산업위생의 역활

김정만,홍대용 카톨릭대학 산업의학 센타 산업의학연구소 1990 韓國의 産業醫學 Vol.29 No.4

鉛暴露 作業者의 鉛中毒 早期發見을 위한 集團檢診法 改善方案에 관한 硏究

홍대용,김장락,정주화,최현림,윤형렬 慶尙大學校 1995 論文集 Vol.34 No.1

This study was carried out to evaluate the feasibility of current lead indicators used in screening lead who were sspeted to have been exposed to lead were selected as 'case'and 207 female workers from non-lead industry were selected for 'control'. The results obtained were as follows: 1. The mean values of blood lead for case and control were 31.4㎍/dl, 22.2㎍/dl,respectively. The difference observed in the mean concentration between case and control was statistically signifi-ant(P<0.01) 2. The mean values for blood ZPP by hematofluorometer for case and control were 31.3㎍/dl, 25.4㎍/dl,respectiely. And difference between two groups was statistically significant(P<0.01). 3. No statistically significant correlation was found between working duation and blood lead, blood ZPPlovel. 4. According to the simple correlation analysis,ZPPand urine lead were found to be statistically correlated with blood lead(P<0.01) 5. According to the discriminant analysis using blood lead as a dependent variable, it showed 89.1% predictability when using 40㎍/dl as a cutting value which is used as a screenig cutting value for industry workers health examination, while 81.8% for 30㎍/dl,77.54% for 20㎍/dl, respectively. 6. Lead related simptons which is used for screening the lead ntoxicated patients were used as a dependent variables in multiple regression analysis to find useful lead indicator. And significant independent variables were found to be ZPP, Age, and Hct. 7. Above results suggest that objective evalution of feasibbility of several lead indicators should be developed to correct the disutility of current lead screeng system in Korea.