객체지향데이타베이스에서 접근 패턴을 감안한 적응 선채취 캐슁 기법

사공준,남인길 大邱大學校 科學技術硏究所 1995 科學技術硏究 Vol.2 No.2

If the cache can accurately predict future disk references, access speed will be improved through the use of prefetching. In this paper, the various caching techniques are compared and the queries in an Object-Oriented DataBases are classified into several access patterns. Then we propose an Adaptive Prefetch Caching Method in which both the access patterns of queries and prefetching of the clusters are taken into account. The simulation results for the performance evaluation show that the proposed prefetchng method using the information of the access patterns in queries can achieve better cache performance.

치과주조용 비귀금속 합금의 금속 용출 수준

사공준,박수철,Sakong, Joon,Park, Soo-Chul 대한치과기공학회 2013 대한치과기공학회지 Vol.35 No.1

Purpose: This study was to assess the extents of the release of metals from the non-precious alloys used for dental casting by measuring the differences in the extents of the release of metals by types of alloys, pH level and elapsed time. Methods: Uniform-sized specimens(10 each) were prepared according to the Medical Device Standard of the Korea Food and Drug Administration(2010) and International Standard Organization(ISO22674, 2006), using four types of alloys(one type of Ni-Cr and one type of Co-Cr used for fixed prosthesis, and one type of Ni-Cr and one type of Co-Cr used for removable prosthesis). A total of 12 metal-release tests were performed at one-day, three-day, and two-week intervals, for up to 20 weeks. The metal ions were quantified using an Inductively Coupled Plasma-Atomic Emission Spectrometer. Results: The results showed that the extent of corrosion was higher in the ascending order of Jdium-$100^{(R)}$, Bellabond-$Plus^{(R)}$, Starloy-$C^{(R)}$, and Biosil-$F^{(R)}$. The lower the pH and the longer the elapsed time were, the greater the increase in metal corrosion. At pH 2.4, the release of Ni from Jdium-$100^{(R)}$, a Ni-Cr alloy, was up to 15 times greater than the release of Co from the Co-Cr alloy from two weeks over time, indicating that the Ni-Cr alloy is more susceptible to corrosion than the Co-Cr alloy. Conclusion: It is recommended that Co-Cr alloy, which is highly resistant to corrosion, be used for making dental prosthesis with a non-precious alloy for dental casting, and that non-precious alloy prosthesis be designed in such a way as to minimize the area of its oral exposure. For patients with non-precious alloy prostheses, a test of the presence or absence of periodontal tissue inflammation or allergic reaction around the prosthesis should be performed via regular examination, and education on the good management of the prosthesis is needed.

일부 지역주민의 수은 노출, 유입경로 및 건강영향

사공준,전만중,이경순,양원호,신덕용,정재욱 대한직업환경의학회 2011 대한직업환경의학회 학술대회 논문집 Vol.2011 No.11

수산물채취 잠수부의 작업특성과 잠수관련질환의 양상

사공준,SaKong, Joon 대한예방의학회 1998 예방의학회지 Vol.31 No.1

Diving related disease including decompression sickness is an important occupational health problem and diving fishermen remain a fairly hazardous occupation in Korea. To prevent diving related disease, we investigate diving patterns, incidence of diving related diseases, and contributing factors of 433 diving fishermen of three coast interviewing and mailing questionnaire in 1996. Mean age of divers was 39.7 years, ranged from 24 to 58 years, 92.8% of these were male, and 58.4% of divers were high school graduates. Mean duration of work as a diver was 12.9 years, ranged from 2 to 40 years. It was found that 70.4% of divers were using hookah system, 22.2% of helmet, and only 2.5% SCUBA. About half of them have learned diving skills from other divers. The peak season of diving was from April to June and mean working days were 20.3 days per month during the peak season. On the average, the divers dived 5-6 times, ranged from 1 to 10 times a day with 51.1 minutes of diving time, ranged from 20 to 120 minutes, at 30 m or 40 m in depth, and 35.5 minute of interval on surface. Most divers ascended slowly making decompression stop, yet the decompression profile used was not based on any scientific knowledge except for their own experiences. It appeared that each diving system had slightly different diving patterns. There were 282(65.0%) divers that suffered from DCS in 1995 and 31.2% of divers were given recompression therapy at a medical facility since they worked as diving fishermen. Skin and musculoskeletal complaints were common symptoms of DCS and 39% of divers experienced a voiding difficulty. In univariate analysis, females have an increased frequency of DCS(93% vs 66% for males). Old age, long duration of work, helmet diving, diving time, diving depth, repetitive diving, and blow up were all contributing factors to DCS. It was found that most diving patterns exceed no decompression limit and did not use the standard decompression table. This suggests that most of divers are at high risk of developing diving related disease with prolonged dives and lengthy repetitive diving in deep depth. Considering the diving patterns and economic aspect of professional diving, the incidence of DCS among diving fishermen in Korea will not decrease in the near future. These findings suggest that periodical health surveillance for divers, and education of health and safety are important for reducing the risk of diving related disease in the population of diving fishermen.

대구지역 택시기사들의 혈중 연농도

사공준,강복수,정종학,SaKong, Jun,Kang, Pock-Soo,Chung, Jong-Hak 대한예방의학회 1990 예방의학회지 Vol.23 No.3

배기가스내 연에 노출될 위험이 가장 큰 직업의 하나인 택시기사들의 혈중연농도를 측정하고 운전경력에 따른 연농도의 분포양상 및 그 상관요인을 규명하여 배기가스내의 연이 택시기사들의 건강에 미치는 영향 및 그로 인한 장애를 예방하기 위해, 1989년 8월 1일부터 동년 8월 31일까지 대구시에 소재한 택시회사 2개소의 남자기사 90명과 대구시내에 거주하는 대조군 50명을 대상으로 면접조사를 하고 정맥혈을 채취하여 원자화무염광로를 부착한 원자흡광광도계로 분석하였다. 택시기사들의 평균혈중연농도는 $26.34{\pm}6.53{mu}g/dl$, 대조군의 경우 $20.77{\pm}4.80{\mu}g/dl$로 유의한 차이가 있었다(p<0.01). 운전경력에 따른 혈중연농도는 유의한 차이가 없었으며 운전경력과 혈중연농도의 상관성은 거의 없었다. 흡연습관과 혈중연농도의 관계에서는 택시기사 및 대조군 모두에서 흡연군이 높은 혈중연농도를 나타내었으나 통계학적으로 유의하지는 않았다. Taxi drivers are exposed to vehicular exhaust aerosols which are a mar source of atmospheric lead pollution in Korea where lead additives are incorporated in petrol. To investigate the blood lead concentration, their correlation factors and influences on taxi drivers, samples were collected from 90 taxi drivers who were living in the Taegu City, during August, 1989. Blood lead concentration was estimated by the atomic absorption spectrophotometer (IL.551) equipped with flameless furnace atomizer (IL.665). The results were analyzed statistically and compared with control group selected urban population. The mean blood lead concentration of taxi drivers and control group were $26.34{\pm}6.53{mu}g/dl\;and\;20.77{\pm}4.80{\mu}g/dl$ respectively (p<0.01). No significant correlation was observed between the blood lead concentration of taxi drivers and driver career (r=0.093). There were no difference of statistical significance in the blood lead concentration of smokers and nonsmokers.

초등학생들의 혈중 수은 농도와 신경행동기능과의 관련성

사공준,전만중,윤성호,홍윤철,이철갑,김영기,하미나,권호장 大韓産業醫學會 2010 대한직업환경의학회지 Vol.22 No.4

Objectives: This study was conducted to examine the effect of blood mercury on neurobehavioral performance in Korean elementary school students. Methods: We measured the blood mercury concentration in 1,077 elementary school students from Seoul, Busan, Daegu and Gwangju, then the students underwent computerized neurobehavioral test. Results: The mean concentration of blood mercury of study subjects was 2.10 ㎍/L. An increased blood mercury was associated with an increased reaction time in digit addition and symbol digit. Conclusions: The blood mercury concentration of study subjects was very high compared to findings in a foreign country. We found several associations between blood mercury level and neurobehavioral performance. 목적: 이 연구는 우리나라 초등학생들의 혈중 수은 농도를 측정하고, 컴퓨터 신경행동검사를 실시하여 혈중 수은 농도가 신경행동기능에 미치는 영향을 평가하고자 하였다. 방법: 서울, 부산, 대구, 광주지역의 초등학생 1,077명을 대상으로 혈중 수은 농도를 측정하고, 컴퓨터 신경행동검사(단순반응시간, 선택반응시간, 숫자더하기, 부호숫자 짝짓기)를 실시하였다. 결과 : 연구대상자들의 평균 혈중 수은 농도는 2.10 ㎍/L였다. 신경행동검사 중 숫자더하기와 부호숫자 짝짓기에서 일정 수준의 혈중 수은 농도 이후부터 혈중 수은 농도가 증가함에 따라 반응시간이 증가하는 경향이 나타났으며 반응시간이 증가하기 시작하는 혈중 수은 농도는 숫자더하기에서 7 ㎍/L, 부호숫자 짝짓기에서 4 ㎍/L였다. 결론: 연구대상자들의 혈중 수은 농도는 외국의 결과에 비해 매우 높았다. 신경행동검사 항목 중 숫자더하기 및 부호숫자 짝짓기 검사에서 혈중 수은 농도와 관련성이 있었다. 그러나 인과관계를 증명하기 위해서는 추가적인 연구가 필요하다.

유기용제 노출자에 대한 신경행동학적 평가

사공준 가톨릭대학산업의학센타 산업의학연구소 2002 韓國의 産業醫學 Vol.41 No.1

자동차 페인트 도장공에 있어서 컴퓨터를 이용한 신경행동검사 수행기능의 평가

사공준,정종학,Sa, Kong-Joon,Chung, Jong-Hak 대한예방의학회 1994 예방의학회지 Vol.27 No.3

A cross-sectional study was performed to evaluate the effects of chronic low-dose solvent on neurobehavioral performance of 118 male car painters. A control group of 113 workers matched for age was selected from different sections of the factory. The mean age and the mean duration of employment were 33 years and 6.7 years in both groups. Mean years of education were 11.4 years in car painters and 11.8 years in controls. Each worker completed a medical and occupational questionnaire and four tests of Swedish performance evaluation system. These included simple reaction time, symbol digit, digit span and finger tapping speed. Althougth the mean duration of employment was 6.7 years, comparison of mean performance showed a significantly poorer performance on simple reaction time (p<0.05), symbol digit(p<0.01) and digit span(p<0.05) in car painters. In univariate analysis, age and educational level contributed to poorer performance on symbol digit and digit span. Smoking appeared to slow finger tapping speed in car painters. Performance of four tests of car painters exposed to high level of solvent was poorer than that of car painters exposed to low level. In multiple regression models, controlling for age, alcohol, smoking and shift work, solvent exposure was found to be associated with performance of simple reaction time, symbol digit and digit span and exposure to high level of solvent was related to poorer performance of symbol digit and digit span.

개인의 특성과 검사조건이 신경행동검사의 신뢰도에 미치는 영향

사공준,전만중,성낙정,김규태 大韓産業醫學會 2003 대한직업환경의학회지 Vol.15 No.2

목적: 대상자의 특성과 검사조건 중 성, 연령, 교육수준, 컴퓨터 친숙도, 검사간격 및 검사시간대의 차이가 신경행동검사의 재검사 신뢰도에 미치는 영향을 평가하였다. 방법: 의과대학생 85명(남자 45명, 여자 40명)과 병원근무자 35명(남자 23명, 여자 12명)을 대상으로 연령, 성 교육수준, 컴퓨터 친숙도를 조사하였다. 84명을 1개월 간격, 20명을 1년 간격, 16명을 3년 간격으로 검사 및 재검사를 실시하였으며 65명을 동일한 검사시간대에, 44명을 다른 시간대에 재검사를 실시하였다. 컴퓨터 신경행동검사로는 SPES-K 중 단순반응시간, 숫자더하기, 부호숫자 짝짓기, 숫자외우기 및 손가락 두드리기를, 면접식 신경행동검사 중 Benton 시각기억검사, 숫자부호 짝짓기, 숫자외우기, 목적점찍기 및 핀꽂기의 재검사 신뢰도를 요인에 따라 층화하여 비교하였다. 결과: 컴퓨터 신경행동검사 중 숫자더하기, 부호숫자 짝짓기, 숫자외우기 및 손가락 두드리기의 재검사 신뢰도가 다른 검사에 비해 연령과 성별의 영향을 적게 받았으며 손가락 두드리기의 재검사 신뢰도가 다른 검사항목에 비해 교육수준의 차이의 영향을 적게 받았다. 컴퓨터 신경행동검사항목 중 단순반응시간의 재검사 신뢰도가 다른 검사들에 비해 컴퓨터에 대한 친숙도에 따른 차이가 크게 나타났다. 부호숫자 짝짓기와 손가락 두드리기의 재검사 신뢰도는 다른 검사에 비해 검사간격의 영향을 적게 받았으며 컴퓨터 신경행동검사 중 숫자더하기, 숫자외우기와 손가락 두드리기 및 면접식의 숫자부호 짝짓기의 재검사 신뢰도가 다른 검사들에 비해 검사시간대 차이의 영향을 적게 받았다. 결론: 향후 산업장 근로자들을 대상으로 한 신경행동검사를 선택하는데 있어 면접식 신경행동검사에 비해 컴퓨터 신경행동검사의 재검사 신뢰도가 상대적으로 안정적으로 나타났으며 이는 우리 나라 근로자의 특성과 산업보건제도에 적합한 신경행동검사 배터리의 구성에 도움이 될 것으로 생각된다. Objectives: This study was conducted to select neurobehavioral tests that are more reliable and less affected by subjects characteristics and test conditions. Methods: Five computerized and five traditional neurobehavioral tests and retests were administered to 85 medical school students and 35 hospital workers. The computerized tests consisted of the Simple Reaction Time, Addition, Symbol Digit, Digit Span, and Finger Tapping Speed, while the traditional tests comprised the Benton Visual Retention test, Digit Symbol, Digit Span, Pursuit Aiming, and pegboard. In addition, the effects of various factors on the reliability of the neurobehavioral tests, including age, sex, educational level, computer familiarity, test intervals, and test time of day, were also evaluated. Results: Among the computerized neurobehavioral tests, the reliability of Addition, Symbol Digit, Digit Span, and Finger Tapping Speed were not affected significantly by age, sex, test interval, or computer familiarity. It was found that Finger Tapping Speed is not affected by educational level. When the time of retest was incongruous with the time of the first test, test-retest reliability was lower in most neurobehavioral tests except computerized Addition, Digit Span, and Finger Tapping Speed, and traditional Digit Symbol. Conclusions: These results suggest that the computerized Addition, Symbol Digit, Digit Span, and Finger Tapping Speed, and the traditional Digit Symbol are more satisfactory for our purposes. These results should facilitate selection of the most appropriate tests for periodical evaluation of the central nervous system of workers exposed to neurotoxic substances in Korea.

면접 및 컴퓨터 신경행동검사의 신뢰도평가

사공준,정종학,전만중,신말숙 大韓産業醫學會 2000 대한직업환경의학회지 Vol.12 No.4

목적 : 신경독성물질에 폭로되는 근로자들의 중추신경계장애를 조기에 발견하기 위한 도구로서 우리 나라 근로자들의 특성과 산업보건제도에 적합한 신경행동검사를 선택하기 위하여 면접과 컴퓨터 신경행동검사의 신뢰도를 평가하였다. 방법 : 의과대학생 85명과 병원근무자 35명을 대상으로 SPES중 단순반응시간, 숫자더하기, 부호숫자 짝짓기, 숫자외우기 및 손가락 두드리기를, 면접식 신경행동검사 중 숫자부호 짝짓기, 숫자외우기, 목적점찍기, 핀꽃기 및 trenton 시각기억검사의 신뢰도를 검사-재검사법을 이용하여 평가하였다. 결과 : 컴퓨터 신경행동검사 중 숫자더하기 평균반응속도의 신뢰도(재검사 신뢰도계수 0.90)가 가장 높았으며 손가락 두드리기(재검사 신뢰도계수 열수 0.89, 우수 0.85), 부호숫자 짝짓기(재검사 신뢰도 계수 0.82) 및 숫자외우기(재검사 신뢰도계수 0.74)의 순서로 신뢰도가 감소하였다 면접식 신경행동검사 중 숫자부호 짝짓기의 재검사 신뢰도계수가 0.86, 목적점찍기의 재검사 신뢰도계수가 0.72로서 trenton 시각기억검사(재검사 신뢰도계수 0.64), 핀꽃기(재검사 신뢰도계수 0.64) 및 숫자외우기의 총점(재검사 신뢰도계수 0.60)에 비해 다소 높았다. 결론 : 신경행동검사의 신뢰도를 검사-재검사를 통하여 평가한 결과 인지기능영역에서는 컴퓨터 부호숫자 짝짓기, 숫자외우기와 면접식 숫자부호 짝짓기가, 운동기능영역에서는 손가락 두드리기의 신뢰도가 다른 검사항목에 비해 상대적으로 높은 것으로 평가되었으며 이러한 결과는 신경행동검사의 선택에 도움이 될 것으로 생각된다. Objectives : Thls study was conducted to select more reliable neurobehavioral tests that are compatible with the characteristlcs of Korean workers and their health management system. Methods : To compare the reliability of neurobehavioral tests, test and retest of five computerized and five traditional neurobehavioral tests administered to 85 medical school students and 35 hospital workers. The computerized tests include Simple reaction time, Addition, Symbol digit, Digit span, and Finger tapping speed, while the traditional tests include the trenton visual retention test, Digit symbol, Digit span, Pursuit aiming, and Pegboard. Results : Computerized Addition was found to have the highest test-retest reliability (0.90) of and followed by Finger tapping speed (nondominant hand, 0.89, dominant hand, 0.85), Symbol digit(0.82), and Digit span(0.74). Only two traditional tests, Digit symbol(0.86), and Pursuit aiming(0.72), showed test-retest reliability coefficient greater than 0.70. Conclusions : These results suggest that the computerized Additions, Symbol digit, Fingel tapping speed, and traditional Digit symbol are more satisfactory for our purposes. These results may allow a reasonable selection of the most appropriate tests for periodical evaluation of central nervous system of workers exposed to neurotoxic substances in Korea.