수산물채취 잠수부의 작업특성과 잠수관련질환의 양상

사공준,SaKong, Joon 대한예방의학회 1998 Journal of Preventive Medicine and Public Health Vol.31 No.1

수산물채취 잠수부에서 발생하는 잠수관련질환을 예방하고, 조기치료에 필요한 기초자료로 활용하기 위하여 잠수부들의 작업환경과 잠수관련질환의 발생양상을 파악하는 단면조사연구를 시행하였다. 수산물채취 어업잠수부 433(서해안 130명, 남해안 220명, 동해안 29명, 기타 54명)을 대상으로 면접과 우편설문을 통하여 인구학적 특성, 취업상태, 잠수기술의 습득경로, 잠수부경력 등의 직업력, 성수기와 비수기의 작업일수, 작업수심, 작업 시기, 잠수방식, 작업횟수, 작업시간, 작업간 휴식시간, 상승시 수중체류 및 급상승의 경험 등 작업특성을 조사하고, 한해 동안 감압병에 이환된 경험과 재압치료 및 잠수관련질환 증상의 경험을 1996년 1월과 2월에 조사하였다. 잠수부들의 평균연령은 39.7세(24-58세), 남자가 92.8%, 고등학교졸업의 학력이 58.4%였다. 평균 잠수부 경력은 12.9년(2-40년), 잠수방식은 후카 70.4%, 헬멧 22.2%, 스쿠버 2.5%였다. 잠수부의 고용상태는 정규 고용 34.7%, 임시고용 54.0%였다. 잠수기술의 습득경로는 선배잠수부 48.5%, 군대 37.6%, 잠수교육기관 12.3%였다. 주된 작업시기는 4-6월이 56%로 가장 많고, 7-9월이 6.4%로 가장 적었다. 성수기의 한달 평균 작업일수는 20.3일, 비수기는 12.5일 이였다. 잠수작업횟수는 하루 5-6회 45.0%, 일회 평균작업 시간은 51.1분, 잠수간 평균휴식시간은 35.5분이었고, 잠수부의 83.6%가 상승시 수중체류를 하고 있으며 80.4%가 급상승을 경험하였다. 후카잠수부의 작업수심은 30m(43%)와 40m(40.4%), 헬멧잠수부는 30m 이하(75.0%), 스쿠버잠수부는 20m 이하(90.9%)에서 주로 작업하였다. 잠수횟수는 주로 후카잠수부가 3-6회(86.5%), 헬멧잠수부가 5-8회(79.9%), 스쿠버잠수부가 4회 이하(81.8%)였다. 잠수부의 65.0%가 지난 일년 동안에 감압병을 경험하였다고 응답하였으며, 잠수작업에 종사한 이후 조사시점까지 전체 잠수부의 31.2%가 재압치료를 받은 경험이 있었다. 감압병의 증상으로는 근골격계 증상과 피부증상이 많았고, 배뇨장애는 39%가 경험하였다고 응답하였다. 혼란효과를 고려하지 않은 단변량분석에서 남자보다 여자에서 감압병의 발생률이 높고, 연령이 증가할수록 감압병의 발생률이 증가하는 경향을 보였다. 잠수부경력이 길수록 감압병의 발생률이 높았으며, 임시 고용에 비해 정규고용의 감압병 발생률이 높았다. 잠수기술은 선배잠수부로부터 습득한 경우가 군대와 교육기관에서 습득한 경우 보다 감압병 발생률이 높았다. 후카잠수부에서 비해 헬멧잠수부의 감압병 발생률이 높았고, 스쿠버잠수부는 감압병을 경험하지 않았다. 작업수심이 깊을수록, 작업횟수가 많을수록 감압병의 발생률이 증가하였다. 급상승의 경험이 있는 군이 없는 군에 비하여 감압병 발생률이 높았다. 일일 평균 40m이상 수심에서 5회 이상 반복잠수를 하는 잠수부가 22.7%, 40m이상의 수심에서 60분 이상 작업하는 잠수부가 6.1%, 5회 이상 반복잠수를 하면서 60분 이상 작업하는 잠수부가 29.1%였다. 작업 횟수가 5회 이상인 군의 감압병 발생률이 4회 이하인 군에 비해 유의하게 높았다. 많은 수의 잠수부가 잠수관련질환에 이환되고 있으며, 감압규정이 무시되고 있는 잠수부의 근무여건을 고려하면 잠수관련질환은 앞으로도 지속적으로 발생할 것으로 예상되므로 2차예방에 보다 많은 관심이 필요하며 잠수관련질환의 발생과 유병에 관한 지속적인 연구, 정기적인 건강진단제도, 잠수장비에 관한 규정 및 안전과 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.

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.

잠수함 승조원에 있어서 항해에 따른 신경행동기능의 변화

사공준 ( Joon Sakong ),정형배 ( Chung Hyung-bae ) 국군의무사령부 1995 대한군진의학학술지 Vol.26 No.1

폐금속광산이 인근지역 주민건강에 미치는 영향

사공준 ( Joon Sakong ) 영남대학교 기초/임상의학연구소 2007 Yeungnam University Journal of Medicine Vol.24 No.2S

About 1,000 metal mines have been abandoned all over the country in the Korea. Major reasons for mine closure may be mainly due to poor economies of the commodity making mining unprofitable, and technical difficulties, Abandoned mines are known to contaminate soil, surface water, and private drinking water wells with toxic metals and arsenic (As), Little attention is given, however, to sites in rural areas with low population densities where natural, geologic sources of contaminants might also occur. Abandoned heavy metal mines have been identified as one of the major concerns because of their significant long-term environmental problems. The topic of abandoned mines is complex because of the associated financial and legal liability implications. 1) In the Korea, most of the metal mine were in operation from 1940s to 1970s, before ceasing operation because of the decline in world market price for the commodity. Mine-waste calcines (retorted ore) were produced during mining and these calcines were dumped into nearby mine. It is estimated that about 50,000 people reside in the nearby abandoned mines. Recently the Korean government decided to apply public health assessment for the investigation of increasing complaints of unusual symptoms or public concern among residents of vicinity of abandoned mines. Several health reports revealed significant elevation of blood lead, cadmium, mercury and urine arsenic levels exceeding the background level or recommended exposure level. Even though the heavy metal specific toxic symptoms were not found, the association was seen between high blood metal levels and the distance from dumping area to residential district, These findings emphasizes the need to test soil, corps and drinking water in the vicinity of abandoned mines to determine the extent of risk to human health and to reduce the estimated carcinogenic risk and the noncarcinogenic hazard.

ADAS CAN-FD 네트워크 응답시간 최적화 연구

사공준(Sakong Joon),안송이(Songyi An) 한국자동차공학회 2016 한국자동차공학회 학술대회 및 전시회 Vol.2016 No.11

구미지역 미용업 종사자들의 눈, 피부, 호흡기 증상 경험률

사공준(Joon Sakong),김만복(Man-Bok Kim) 한국인체미용예술학회 2013 한국인체미용예술학회지 Vol.14 No.3

This research investigated the prevalence of ocular, dermatologic, and respiratory symptoms caused by hairdressers' exposure to harmful chemical substance. It compared the degree of risk of experiencing symptoms between the hairdressers' group and the control group, and evaluated the relationship between hairdressers' types of work and work characteristics and the symptoms. Fifty-three beauty parlors located in Gyeongbuk Gumi city were extracted through convenience sampling. The subjects were then divided into the exposure group composed of 103 hairdressers, and the control group composed of 98 ordinary persons. This research showed that the ocular, dermatological, and respiratory system symptoms in the hairdressers' group were significantly higher than those in the control group. Moreover, the degree of risk in experiencing symptoms in the hairdressers' group was 2∼3 times higher in eye-related symptoms, 3 times higher in red spots in the skin-related symptoms, and 2∼3 times higher in respiratory system-related symptoms compared to those in the control group. To prevent occupational dyscrasia among hairdressers, it is necessary for them to wear personal protective equipments, wash hands after work, improve working environment, and develop mild beauty treatment products. Symptoms among workers should be early detected and management, such as task switching, should be taken.

초등학교 교실 실내공기 중 유해유기물질의 계절별 농도 변화에 관한 연구

사공준(Joon Sakong),곽홍탁(Hong-Taak Kwaak) 한국환경교육학회 2012 環境 敎育 Vol.25 No.3

The purpose of this study is to measure and analyze the seasonal concentrations of formaldehyde, the total volatile organic compounds (TVOCs), toluene (C?H?), benzene (C?H?), ethyl-benzene (C?H?C₂H?), xylene (C?H₄(CH₃)₂), and styrene (C?H?) in the both classrooms of newly-built school, as of September 2008, and control school. As a result, formaldehyde and volatile organic compounds among pollutants were just over 100μg/m<SUP>3</SUP>, standard level by law, both in the newly-built school and control school in June and high temperatures in September. As for the total volatile organic compounds (TVOCs), it exceeded 6 times and 3.6 times the standard level in the indoor air by law, 400μg/m<SUP>3</SUP>, in newly-built school and control school respectively, which was usually caused by new learning & teaching tools and clothes of students in March beginning new term. In case of benzene, nothing unusual was found as its highest concentration was 2.9μg/m<SUP>3</SUP> in both schools. However, the concentration of toluene, when its seasonal variation was measured, came to 390.5μg/m<SUP>3</SUP> in control school, reaching 400μg/m<SUP>3</SUP>, the standard level of the total volatile organic compounds, and to 688.0μg/m<SUP>3</SUP> in the newly-built school in March beginning new term. This shows that the concentration of toluene was significantly high in the newly-built school, reaching to 1.7 times the standard level, while the other hazardous organic compounds such as ethyl-benzene, xylene and Styrene, were similar in seasonal concentrations or no detected.

새차 실내공기 중 포름알데히드, 휘발성 유기화합물과 운전자의 인지기능

사공준(Joon Sakong),백성옥(Sung-Ok Baek),전만중(Man-Joong Jeon) 한국실내환경학회 2009 한국실내환경학회지 Vol.6 No.2

Studies on the indoor air quality inside newly producted vehicle have made mainly mention of the concentrations for indoor air pollutants or of subjective symptoms, such as irritated eyes and nose, headache and dizziness. That is, there has been no report about how poor indoor air quality inside newly producted vehicle affects vehicle drivers. We measured the indoor air pollutants inside newly producted vehicle and evaluated the neurobehavioral performance of drivers, using a computerized neurobehavioral test (color word vigilance), between a newly producted and a 11-year-old vehicle. Inside the newly producted vehicle, the formaldehyde concentration with closed window was 19.1㎍/㎥. The concentration of VOCs with closed window was 3.9㎍/㎥ for benzene, 316.7㎍/㎥ for toluene, 20.5㎍/㎥ for ethylbenzene, 47.7㎍/㎥ for m,p-xylene, 15.1㎍/㎥ for o-xylene, and 15.3㎍/㎥ for styrene. The neurobehavioral performance of drivers inside newly producted vehicle with the computerized neurobehavioral test was 11.05% lower than that for those inside 11-year-old control vehicle. These results suggest that the poor indoor air quality inside newly producted vehicle affects the neurobehavioral performance of driver and a proper evaluation of the indoor air quality inside newly producted vehicle is required into the health effects of pollutants with objective tool, in addition to the level of pollution.

경남지역 치과의원 의료폐기물 관리실태

김해진,사공준,Kim, Hae-Jin,SaKong, Joon 한국환경보건학회 2012 한국환경보건학회지 Vol.38 No.4

Objectives: The purpose of this study was to prevent health problems and environmental contamination resulting from inappropriate management of dental wastes and to provide reference data for revision and supplementation of dental clinic waste management guidelines. Methods: From 640 total of dental clinics registered in 16 cities and counties in Gyeongsangnam-do, 100 (60 in Changwon (Masan, Changwon), 29 in Gimhae, and 11 in Jinju) were included in this study. From July 2010 to September 2010, investigators visited the 100 dental clinics and conducted survey interviews using a structured survey questionnaire regarding disposal methods for liquid wastes (suction pump, spittoon container waste, used liquid disinfectants, and X-ray developer), and disposal methods for solid waste (suction pump, spittoon container waste, and general medical waste). Results: All the 100 dental clinics were found to treat liquid waste from suction pumps and spittoon containers in the same manner as general waste water. Nineteen percent of the clinics treated solid waste that was not filtered through the filter of a suction pump as general waste. Fifty or more percent of the clinics treated solid waste in spittoon containers as general waste. Seventy percent of the clinics used disinfectant solution, although most of them treated used disinfectants in the same manner as general waste water. Some clinics treated used X-ray developer and X-ray fixer in the same manner as general waste water. In most of the clinics, used drapes were washed within the clinic. Conclusions: It was found that waste water and dental wastes at some dental clinics were treated in inappropriately. Thus, in conclusion, the development of guidelines regarding proper management of liquid and solid dental waste at dental clinics is required, and hygiene and environmental training for workers at dental clinics is necessary.

축전지 공장 근로자들의 혈중 Zinc Protoporphyrin에 대한 코호트 연구

전만중,이중정,사공준,김창윤,김정만,정종학,Jeon, Man-Joong,Lee, Joong-Jeong,SaKong, Joon,Kim, Chang-Yoon,Kim, Jung-Man,Chung, Jong-Hak 대한예방의학회 1998 Journal of Preventive Medicine and Public Health Vol.31 No.1

To investigate the effectiveness of the interventions in working environment and personal hygiene for the occupational exposure to the lead, the blood zinc protoporphyrin (ZPP) concentrations of 131 workers (100 exposed subjects and 31 controls) of a newly established battery factory were analyzed. They were measured in every 3 months up to 18 months. Ai. lead concentration (Pb-A) of the workplaces was also checked for 3 times in 6 months interval from August 1987. Environmental intervention included the local exhaust ventilation and vacuum cleaning of the floor. Intervention of the personal hygiene included the daily change of clothes, compulsory shower after work and hand washing before meal, prohibition of cigarette smoking and food consumption at the work site and wearing mask. Mean blood ZPP concentration of the controls was $16.45{\pm}4.83{\mu}g/d\ell$ at the preemployment examination and slightly increased to $17.77{\pm}5.59{\mu}g/d\ell$ after 6 months. Mean blood ZPP concentration of the exposed subjects who were employed before the factory was in operation (Group A) was $17.36{\pm}5.20{\mu}g/d\ell$ on employment and it was increased to $23.00{\pm}13.06{\mu}g/d\ell$ after 3 months. The blood ZPP concentration was increased to $27.25{\pm}6.40{\mu}g/d\ell$ on 6 months (p<0.01) after the employment which was 1 month after the initiation of intervention program. It did not increase thereafter and ranged between $25.48{\mu}g/d\ell$ and $26.61{\mu}g/d\ell$ in the subsequent 4 results. Mean blood ZPP concentration of the exposed subjects who were employed after the factory had been in operation but before the intervention program was initiated (Group B) was $14.34{\pm}6.10{\mu}g/d\ell$ on employment and it was increased to $28.97{\pm}7.14{\mu}g/d\ell$ (p<0.01) in 3 months later(1 month after the intervention). The values of subsequent 4 tests were maintained between $26.96{\mu}g/d\ell$and $27.96{\mu}g/d\ell$. Mean blood ZPP concentration of the exposed subjects who were employed after intervention program had been started (Group C) was$21.34{\pm}5.25{\mu}g/d\ell$ on employment and it was gradually increased to $23.37{\pm}3.86{\mu}g/d\ell$ (p<0.01) after 3 months, $23.93{\pm}3.64{\mu}g/d\ell$ after 6 months, $25.50{\pm}3.01{\mu}g/d\ell$ after 9 months, and $25.50{\pm}3.10{\mu}g/d\ell$ after 12 months. Workplaces were classified into 4 parts according to Pb-A. The Pb-A of part I, the highest areas, were $0.365mg/m^3$, and after the intervention the levels were decreased to $0.216mg/m^3$ and$0.208mg/m^3$ in follow-up test. The Pb-A of part II which was resulted in lowe. value than part I was decreased from $0.232mg/m^3$ to $0.148mg/m^3$, and $0.120mg/m^3$ after the intervention. The Pb-A of part III was tested after the intervention and resulted in $0.124mg/m^3$ in January 1988 and $0.181mg/m^3$ in August 1988. The Pb-A of part IV was also tested after the intervention and resulted in $0.110mg/m^3$ in August 1988. There was no consistent relationship between Pb-A and blood ZPP concentration. The blood ZPP concentration of the group A and B workers in the part of the highest Pb-A were lower than those of the workers in the parts of lower Pb-A. The blood ZPP concentration of the workers in the part of the lowest Pb-A increased more rapidly. The blood ZPP concentration of the group C workers was the highest in part III. These findings suggest that the intervention in personal hygiene is more effective than environmental intervention, and it should be carried out from the first day of employment and to both the exposed subjects, blue color workers and the controls, white color workers. 혈중 ZPP 농도를 생물학적 모니터링 표지자로 사용하여 새로 설립되는 축전지 제조 공장에서 작업환경과 개인위생에 대한 개선조치의 영향을 관찰하기 위하여 연취급 근로자 100명을 대상으로 입사한 시기를 기준으로 3개의 군으로 구분한 후 채용시 측정된 혈중 ZPP 농도와 약 3개월 간격으로 12-18개월간 측정되어 보관된 기록 중 혈중 ZPP 농도 자료를 분석하였다. 각 군은 개선조치 시행전인 1987년 8월의 작업장의 기중 연 농도를 기준으로 $0.30mg/m^3$ 이상인 단위 부서들을 제 I 부서로, $0.30mg/m^3$ 미만인 단위 부서들을 제 II 부서로, 비교적 기중 연 농도가 낮을 것으로 예측되어 1988년 1월부터 새로 기중 연 농도가 측정된 단위 부서들을 제 III부서로, 그리고 작업장소가 일정하지 않고 이동하면서 근무하는 단위 부서들을 제IV부서로 대분하였고, 1987년 8월부터 약 6개월 간격으로 측정된 작업장의 기중 연 농도를 분석하였다. 또한 대조군 31명중 6개월째까지 관찰되었던 22명도 채용시와 6개월 후에 측정된 혈중 ZPP 농도의 변화를 분석하였다. 작업환경 및 개인 위생에 관한 개선조치를 1987년 8월 중순부터 시행하였으며, 주 1회 보건관리자를 통한 보건교육과 건강상담이 실시되었다. 부서별 기중 연 농도는 1987년 8월부터 약 6개월 간격으로 3회 측정된 결과, 제 I 부서는 처음에는 $0.365mg/m^3$였으나 작업환경개선조치 후 $0.216mg/m^3$, 1년후에는 $0.208mg/m^3$로 감소되었고, 제 II 부서는 처음에 $0.232mg/m^3$였는데 개선조치 후 $0.148mg/m^3,\;0.120mg/m^3$가 되었으며, 제 III 부서는 1988년 1월의 측정치가 $0.124mg/m^3$였고, 8월에는 $0.081mg/m^3$였다. 제 IV 부서는 1988년 8월에 $0.110mg/m^3$였다. 대조군에서의 혈중 ZPP 농도는 31명중 6개월째까지 관찰되었던 22명에서 채용시와 6개월 후가 각각 $16.45{\pm}4.83{\mu}g/d\ell$과 $17.77{\pm}5.59{\mu}g/d\ell$로 유의한 차이가 없었다. 공장이 가동되기 전에 입사한 A군에 있어서는 채용시 혈중 ZPP농도가 $17.36{\pm}5.20{\mu}g/d\ell$였고, 3개월째에는 $23.00{\pm}13.06{\mu}g/d\ell$였으며, 개선 조치가 시행된 직후인 6개월째에는 $27.25{\pm}6.40{\mu}g/d\ell$로 유의하게 증가되었고(p<0.01), 최고치를 나타내었다. 9개월째에 측정된 농도는 $25.48{\pm}5.17{\mu}g/d\ell$로 6개월째의 검사 농도보다 유의하게 감소된 결과를 나타내었다(p<0.05). 12개월째부터 3회의 측정치는 유의한 증가나 감소가 없이 대체로 비슷한 농도의 양상을 보였다. 공장이 가동된 후 개선조치가 시행되기 전에 입사한 B군의 경우에 있어서는 채용시에 혈중 ZPP농도가 $14.34{\pm}6.10{\mu}g/d\ell$였고, 개선조치가 시행된 직후인 3개월째에는 $28.97{\pm}7.14{\mu}g/d\ell$로 급격히 증가되었으며 통계적으로 유의하였다(p<0.01). 6개월째부터 4회의 측정치는 유의한 증가나 감소가 없이 비슷한 농도의 양상을 보였다. 개선조치가 시행된 후 입사한 C군에서는 채용시 혈중 ZPP 농도가 $21.34{\pm}5.25{\mu}g/d\ell$였고, 입사한 후 3개월째에는 $23.37{\pm}3.86{\mu}g/d\ell$로 유의하게 증가되었으며(p<0.01), 6개월째에는 $23.93{\pm}3.64{\mu}g/d\ell$의 농도를 보였고, 9개월째에는 $25.50{\pm}3.01{\mu}g/d\ell$로 유의한 증가를 보였다(p<0.01). 계속하여 3개월 뒤 측정된 12개월째에는 그 농도를 계속 유지하였으며, 서서히 증가하는 경향을 보였다. 부서별