• 수산해양기술연구
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• 제45권1호
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• pp.46-55
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• 2009

To compare and evaluate the suitability and comfort levels of the environment on board a stern trawl training ship, KAYA(GT: 1737 tons, Pukyong National University), with the international standardization guide ISO 6954:2000(E), measurements of the hull vibration on accommodation areas and working areas of the training ship from July 8 to July 10, 2008 were completed upon KAYA's linear sea route. The vibrations along the z-axis were measured with the use of a 3-axis vibration level meter, which included a marine vibration card. Results show accelerations of the vibrations on the passenger's accommodation area to be 42.0-115.8(average: 78.0, standard deviation(SD): 21.0) mm/$s^2$, which is largely below the permissible upper limit, but 75 % of the observation points exceeded the permissible lower limit of 71.5 mm/$s^2$, indicating a comfortable environment. The accelerations of the vibration in a frequency of 10-24Hz lowering the visual performance were measured at 2.5-12.0(average: 7.6, SD: 3.1) mm/$s^2$. The crew s accommodation area experienced vibration accelerations of 42.9-82.3(average: 93.1, SD: 53.1) mm/$s^2$, which is generally below the permissible upper limit of 214.0 mm/$s^2$, and 62.5% of the observation points did not exceed the permissible lower limit of 107.0 mm/$s^2$, denoting a level of comfort. The acceleration of the vibration in a frequency of 10-24Hz were 4.7-28.3(average: 12.4, SD: 8.8) mm/$s^2$. On the crew s working area the accelerations were measured at 86.9-153.9(average 119.3, SD 18.0) mm/$s^2$. These values were generally below the permissible upper limit of 286.0 mm/$s^2$ and only 12.5% of the observation points did not exceed the permissible lower limit of 143.0 mm/$s^2$, the level at which a high level of comfort is maintained. The accelerations in frequency of 10-24Hz and 30Hz were 9.1-29.8 (average 13.8, SD= 4.5) mm/$s^2$ and 8.9-13.7 (average 11.8, SD 2.1) mm/$s^2$, respectively. In conclusion the boarding environment of the training ship was good in general although an improvement of the vibration condition partially needed on the crew s accommodation area near the engine room.

• Toxicological Research
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• 제18권1호
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• pp.65-71
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• 2002

A benchmark dose (BMD) approach has been evaluated us a replacement for the traditional NOAEL methodology currently being wed to assess the noncancer effects of toxicants. The endocrine disrupt-ing effect of endosulfan which showed decrement of sperm count and testicular testosterone level in animals, was currently reported. The amount of endosulfan used as pesticide in the country has been continuously increased. The aim of this study was to suggest the permissible intake level (PIL), corresponding to Accept-able Daily Intake (ADI), based on endocrine disrupting effect wing BMD. Various animal data were collected by consideration of critical effect showing endocrine disruption and an animal data for reproductive toxicity was selected. The Power model from BMD software for induction of $BMD_10$ having meaning which is the dose at the 95% lower confidence limit on a 10% response was used due to that the form of selected dose-response animal data was continuous data. The $BMD_10$ was estimated to be 0.393 mg/kg/day based on reproductive toxicity showing decrement of sperm count. The permissible intake level (PIL) was calculated by dividing the $BMD_10$ by the uncertainty factors of 100 with consideration of from animal to human and human variability. The PIL as 0.004 mg/kg/day was compared with traditional ADI as 0.006 mg/kg/day based on the incidence of marked progressive glomerulonephrosis and blood vessel aneurysm in males.

• 대한조선학회논문집
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• 제40권4호
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• pp.53-58
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• 2003

Design of the corrugated watertight bulkhead for a bulk carrier is principally determined by the permissible limit of Classification requirements. As the weight of upper and lower stool has considerable portion of the total weight of the transverse bulkhead, optimum design including the stool geometry and size will play an important role on economic shipbuilding. The purpose of this study is focused on the minimization of steel weight using the design variables, which are the shape and the size of the corrugation as well as the upper and lower stools. Discrete variables are used as design variables for the practical design. In this study, the evolution strategies (ES), which can highly improve the possibility of leaching the global minimum point, are selected as an optimization method. Usefulness of this study is verified by comparison with the proven type ship design. As objective function, total weight of the transverse bulkhead including the upper and lower stools is used.

• Environmental Engineering Research
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• 제21권3호
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• pp.247-255
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• 2016

Ten trace elements (Mg, Ca, V, Cr, Mn, Fe, Cu, Zn, Mo, and Cd) were determined in seven traditionally used wild medicinal plants of the Nagas in the North-East India viz Cynoglossum furcatum Wallich, Elsholtzia blanda Bentham, Lycopodium cernuum Linnaeus, Potentilla fulgens Wallich ex Hooker, Swertia macrosperma C.B. Clarke, Thalictrum foliolosum DC and Valeriana jatamansi Jones. Plant samples were dried, weighed, digested and analyzed for their mineral distribution level ranging from trace to major elements by graphite furnace-atomic absorption spectroscopy. All the medicinal herbs studied were found to contain the ten elements analyzed. The elemental concentration is given in mg/kg. Mg and Ca are present in high concentrations in both the roots and leaves of the plant samples. Among trace transition metals Fe had the highest concentration, followed by Mn, Cr, Cu, V, Zn, and Mo. Analysis showed that the toxic Cd element was at a lower concentration and is within the permissible limit of FAO/WHO, California standards and United States Pharmacopeia Limit for Nutritional Supplements.

• 해양환경안전학회지
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• 제13권4호
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• pp.107-112
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• 2007

선박에서 발생하는 진동은 여객의 안락감을 결정하거나 승조원의 근무환경에 미치는 영향이 크므로 매우 중요하다. 선박에서 발생하는 진동은 선박의 속도를 좌우하는 추진방식의 발달과 가장 밀접한 관계가 있다. 이와 갈이 추진력을 발생하기 위하여 선박의 기관실에는 디젤엔진의 연속적인 폭발과정에서 기인하는 강력한 진동이 발생하게 된다. 진동이 인체에 미치는 피해는 생리적인 피해와 심리적인 피해로 발생하게 된다. 진동 환경에 인체가 노출되는 경우, 선내의 진동에 대한 평가는 국제표준화지침인 ISO 6954:2000(E)에 의해 정하고 있다. 본 연구에서는 선박에서 진동이 인체에 미칠 수 있는 영향을 평가하기 위해 ISO 6934:2000(E)에서 규정하는 지침에 의해 선박진동의 영향이 가장 큰 기관실, 기관제어설, 각종선실 및 선교 등에서 발생하는 진동의 크기를 측정 비교하여 평가한다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2007년도 추계학술발표회
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• pp.139-144
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• 2007

선박에서 발생하는 진동은 여객의 안락감을 결정하거나 승조원의 근무환경에 미치는 영향이 크므로 매우 중요하다 선박에서 발생하는 진동은 선박의 속도를 좌우하는 추진방식의 발달과 가장 밀접한 관계가 있다. 이와 같이 추진력을 발생하기위하여 선박의 기관실에는 디젤엔진의 연속적인 폭발과정에서 기인하는 강력한 진동이 발생하게 된다. 진동이 인체에 미치는 피해는 생리적인 피해와 심리적인 피해로 발생하게 된다. 진동 환경에 인체가 노출되는 경우, 선내의 진동에 대한 평가는 국제표준화지침인 ISO 6954:2000(E)에 의해 정하고 있다. 본 연구에서는 선박에서 진동이 인체에 미칠 수 있는 영향을 평가하기위해 ISO 6954:2000(E)에서 규정하는 지침에 의해 선박진동의 영향이 가장 큰 기관실, 기관제어실, 각종선설 및 브리지 등에서 발생하는 진동의 크기를 측정 비교하여 평가한다.

• Earthquakes and Structures
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• 제16권4호
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• pp.437-453
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• 2019

This study investigates a new optimal placement method for viscous dampers between structures in order to prevent pounding of adjacent structures with different dynamic characteristics under earthquake effects. A relative displacement spectrum is developed in two single degree of freedom system to reveal the critical period ratios for the most risky scenario of collision using El Centro earthquake record (NS). Three different types of viscous damper design, which are classical, stair and X-diagonal model, are considered to prevent pounding on two adjacent building models. The objective function is minimized under the upper and lower limits of the damping coefficient of the damper and a target modal damping ratio. A new algorithm including time history analyses and numerical optimization methods is proposed to find the optimal dampers placement. The proposed design method is tested on two 12-storey adjacent building models. The effects of the type of damper placement on structural models, the critical period ratios of adjacent structures, the permissible relative displacement limit, the mode behavior and the upper limit of damper are investigated in detail. The results of the analyzes show that the proposed method can be used as an effective means of finding the optimum amount and location of the dampers and eliminating the risk of pounding.

• 소음진동
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• 제2권4호
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• pp.281-292
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• 1992

Two types of vibration problems are encountered in industrial field: active isolation and passive isolation. In a passive type of vibration isolation, a foundation of a delicated machinery such as TEM, SEM, inspection- probe test, photolithograph, etc. is designed to have a vibration amplitude lower than an acceptable limit. In an active type, the isolation is focused on the vibration reduction caused by the machine itself(pump, motor, press, compressor, etc.). The foundation for such a machine should be so designed as to reduce the transmitted vibration below the permissible level prescribed. At any case, a transmissibility and stability must to be considered. Since an active isolation type is aimed for a vibration source, it is useful to isolate the transmitted vibrations energy from a major vibration source at the specific location. In this paper, a designed methodology of double anti-vibration system has been examined in order to have low transmissibility and reliable stability. Also experiment of scale model behavior has been conducted. Finally, the experiment output of the transfer function is compared to the analytical data.

• 한국축산시설환경학회지
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• 제15권2호
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• pp.107-114
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• 2009

악취에 대한 민원이 많이 증가함에 따라 양돈장의 악취 발생에 대한 기초자료를 얻고자 2008년 6월에서 11월까지 2개의 양돈장(수원시, 화성시 소재)을 선정하여 임신돈사와 부지경계에서 발생하는 악취를 조사하였다. 수원시 소재 A농장의 부지경계에서 암모니아 발생농도는 평균 0.9 ppm 였으나, 조사기간 중 부분적으로 기준치 1 ppm을 초과하였다. 황화수소와 메틸머캅탄은 각각 0.37 ppb, 0.01 ppb로 기준치인 20 ppb와 2 ppb 이하로 조사되었다. 돈사의 암모니아 평균 농도는 3.22 ppm 였고 5 ppm 이하로 유지되다가 돈사가 밀폐되는 11월부터는 증가하기 시작되었다. 황화수소와 메틸머캅탄은 기준치 이하로 나타났다. 화성시 소재 B농장은 임신돈사내 암모니아 평균농도는 16.3 ppm 였고, 10월 이후부터 밀폐상태가 높아짐에 따라 급격히 증가되었다. 황화수소와 메틸머캅탄은 각각 26.66 ppb, 7.45 ppb로 높았다. 이와 같은 원인은 환기불량과 사육환경이 열악하여 돈사내 암모니아 발생농도가 높았으며 돈사외부로 배출된 암모니아와 돈사 옆에 있는 퇴비장에서 발생되는 악취가 혼합되어 부지 경계에서 암모니아 발생농도가 높은 것으로 나타나 돈사의 사육환경 개선과 신속한 분뇨처리 및 미생물제제의 올바른 사용이 필요할 것으로 판단된다.

• 한국환경보건학회지
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• 제33권6호
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• pp.506-512
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• 2007

This study was conducted to describe the exposure levels of welding fumes by the type of manufacturers, work process, welding type and the size of manufacturers, and to find out the trend of chronological changes of airborne welding fume levels. The subjects of this study were 509 manufacturers, consisting of 11 types of manufacturers, 3 work processes, 7 welding types, in Busan from January, 1997 to December, 2005. Airborne concentration of welding fume was determined by manual of National Institute for Occupational Safety and Health (NIOSH), and the data were analyzed by using SPSS 10.0 for Windows program. The mean concentration of airborne welding fume in all manufacturers was $1.29\;mg/m^3$ (Range: $0.01{\sim}3.00\;mg/m^3)$. The level of welding fume was the highest, as $1.96\;mg/m^3$, for manufactures of motor vehicles, trailers and semi-trailers, which was lower than $5.0\;mg/m^3$ of 8 hr-TWA in Korean permissible exposure limit for welding fume. There was a significant difference in the mean levels of welding fumes by work process, showing the highest in welding workshop ($1.39\;mg/m^3$), followed by pipeline welding workshop ($1.26\;mg/m^3$) and engineering workshop ($1.20\;mg/m^3$). Among welding types, the mean level of welding fume was the highest in the type of $CO_2$ & arc welding, as $1.46\;mg/m^3$, followed by $CO_2$ welding ($1.40\;mg/m^3$), shielded metal arc welding ($1.31\;mg/m^3$), spot welding ($1.27\;mg/m^3$), and so on. The highest mean level of welding fume was $1.58\;mg/m^3$ in work process of pipe line welding workshop for the manufacturers of basic iron and steel, and $2.27\;mg/m^3$ in the type of arc welding for the manufactures building ship and boats. By the size of manufacturers, the mean concentration of welding fume for manufactures in small scale with less than 50 workers was the highest as $1.45\;mg/m^3$ (Range: $0.07{\sim}3.00\;mg/m^3)$. The mean level of welding fume was the highest as $1.39\;mg/m^3$ both in 1997 and in 2005, showing a trend of fluctuating periodically within a range of $1.10{\sim}1.39\;mg/m^3$. The above results suggested that more effective control program for work environment producing welding fumes should be developed and applied since there were significant variations in welding fume levels by the type of manufacturers, work processes, welding types, the size of manufactures, and by year.