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오연희,이현경,이원재,이성우,박수성,윤혜원,임문환,심재철,김용탁,김성숙,김정란 동국대학교 경주대학 1993 東國論集 Vol.12 No.-
Acute torsion of the ovary and ovarian mass is a recognized surgical emergency, but rarely has the diagnosis been made preoperatively on the basis of imaging studies. The sonographic findings in 14 cases of surgically proven torsion of the ovary and ovarian mass are described. Mostly cystic ovarian mass, engorged vessel, dilated uterine tube, beak-like echo(torsion site), smooth mass wall thickening an free-fluid collection in cul-de-sac are described. More significant in terms of specificity were the demonstration in 6 cases(42.9%) of the smooth mass wall thickening and in 8 cases(57.1%) of a free fluid in the cul-de-sac. We report the sonographic findings of ovary and ovarian mass torsion that may suggest the preoperative diagnosis of this condition.
산업단지 및 일반생활 지역의 공기 중 톨루엔에 대한 개인노출 및 생체시료의 상관성 분석
이병준(Byoungjun Lee),허 정(Jung Heo),정다영(Dayoung Jung),김순신(Sunshin Kim),류현수(Hyeon-Su Ryu),최민지(Min-Ji Choi),솨이지엔페이(Jian-Fei Shuai),임성국(Sung-Guk Im),양원호(Wonho Yang) 한국환경보건학회 2017 한국환경보건학회지 Vol.43 No.4
Objectives: The purpose of this study was to assess the correlation relationship between personal exposure and urinary hippuric acid in biological monitoring for airborne toluene in an industrial complex and in general environments. Methods: Personal exposure to toluene and its metabolite, hippuric acid, in urine were simultaneously measured in occupational environments area near an industrial complex and in general environments. The study subjects were divided into three types: 137 workers who use organic solvents in the workplace, 210 residents living near a dyeing industrial complex, and 379 residents living in general environments. The toluene exposures of workers and residents were measured by a passive sampler for four days. The urine of participants was sampled when the passive samplers of personal exposure were collected. Results: The toluene and hippuric acid concentrations of workers were the highest, followed by the concentrations of residents living near a dyeing industrial complex and residents living in general environments. The coefficient of correlation between the concentrations of toluene and hippuric acid among workers was 0.749 (p<0.01) in the workplace. On the contrary, correlations between the concentrations of toluene and hippuric acid among residents living near a dyeing industrial complex and residents living in general environments were all not significant. The relationship between the concentrations of hippuric acid and toluene in three types could be described by the exponential growth model. Conclusions: This study analyzed the relationships between toluene exposure and the concentrations of hippuric acid in urine in high, middle, and low exposure environments, and could be described by the exponential growth model.
Demagnetization Scheme for Avoiding Magnetic Mines Under the Exposure of Earth Magnetic Field
Im, Sang Hyeon,Lee, Ho Yeong,Chung, Hyun Ju,Park, Gwan Soo IEEE 2018 IEEE transactions on magnetics Vol.54 No.3
<P>Demagnetization of warship is needed to reduce residual magnetization to avoid the detection of magnetic mines. However, after demagnetized, it could be magnetized again by the earth magnetic field during the operation. In order to accomplish a robust deperming protocol to avoid the influence of earth magnetic field after demagnetization, this paper proposes a demagnetization protocol which utilize the interaction field inside the material to maintain magnetization state of a small coercive particles. By using the Preisach modeling combined with finite-element method, it was confirmed that the proposed protocol reduces the effect of the earth magnetic field and it was verified by the experimental measurements. Coincident results in different coercive materials showed an effectiveness of this protocol.</P>
Reduction of Eddy Current Loss in Metal Sheath of 154 kV Transmission Cable
Sang Hyeon Im,Ki Byung Kim,Gwan Soo Park 한국자기학회 2020 Journal of Magnetics Vol.25 No.2
The power cables in underground transmission lines consist of a conductor, an insulator, and a metallic sheath. The metallic sheath serves to protect the cable from external physical impacts. When a large fault current is applied to the transmission line owing to an accident, the metallic sheath prevents the fault current from penetrating into the transmission-line current and thus enhances the reliability of the transmission line. However, owing to the alternating current flowing through the conductor, an eddy current is generated in the sheath and a loss occurs. Thus, the overall transmission efficiency is reduced. In this paper, an eddy current loss in a metallic sheath was analyzed using an analytical method, and the results thus obtained were verified by comparing them with those obtained using the finite element method. In addition, a design was proposed for reducing the eddy current loss.
A Study on the magnetic field of eddy current caused by the rolling of the Ship
Sang Hyeon Im 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2
In warships made of ferromagnetic materials, permanent magnetic fields generated during the manufacturing process, induced magnetic fields due to changes in the Earth"s magnetic field, and eddy current magnetic fields due to fluctuations of underwater bodies are generated. The above magnetic fields cause damage by magnetically sensitive mines using high-sensitivity magnetic field sensors equivalent to thousands to tens of thousands of the earth"s magnetic field. In order to remove the permanent and induced magnetic fields that account for the majority of the above magnetic fields, research on demagnetization and devices to reduce the permanent and induced magnetic fields of ships is being actively conducted, and damage caused by mines is effectively reduced by reducing the magnetic field of underwater vehicles. However, the relative weight of the eddy current magnetic field is increasing as the permanent and induced magnetic fields are reduced through demagnetization and demagnetization processes. Therefore, in order to prevent damage to the ship by mines, it is necessary to predict the eddy current magnetic field generated by the fluctuation of the ship and generate a magnetic field to offset it. However, if the correct offset current is not passed, the magnetic field measured from the outside becomes larger, which may increase the possibility of damage. In order to prevent such a situation, it should be possible to accurately measure the eddy current when the ship fluctuates. Therefore, it is necessary to quickly and accurately respond to the generated eddy current magnetic field, so immediate calculation by formulas rather than FEM simulation analysis is required. In this paper, the formula for calculating the eddy current in the equivalent model of the ship is summarized. In addition, the eddy current calculation method was verified by simulating the ship"s fluctuations through the 2D FEM program, analyzing the eddy currents generated accordingly, and comparing the analyzed results with the calculated results. 〈그림 본문참조〉