• Progress in Superconductivity
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• v.10 no.1
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• pp.1-5
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• 2008

Magnetocardiography (MCG) is a non-contact, non-invasive, and harmless diagnostic tool to detect the abnormal electrical conductivities of the heart caused by the various coronary artery disease or cardiac muscular disease. The purpose of this study is to identify whether MCG signals and MCG parameter values vary depending on the location of sensor assembly. It will be an important reference for the standard measurement. Four healthy male subjects (33.3$\pm$6.3 years) participated in this study. Basal recording was made at 20 mm apart from the chest surface. All subjects were requested to take a regular breathe while MCG was taken. The gap between the chest surface and the bottom of the sensor assembly was 20, 40, 60, and 80 mm. Recording was made using 64 channel MCG system (Axial type, first order gradiometer) developed by Korea Research Institute of Standards and Science (KRISS). After resting for two minutes in a supine position on the bed in magnetically shielded room, MCG were recorded for 30 s. As the sensor location is getting away from the chest surface signal, the amplitude of R and T wave peak decreases to 70% (at 40 mm gap), 50% (at 60 mm), and 37% (at 80 mm) of the reference strength measured (y = $1.3903e^{-0.0169x}$, $R^2$ = 0.99; where y=amplitude remained after reduction, x=distance between chest surface and sensor location). The regression equations may be used as a good reference to calculate how much strength will be decreased by the distance. In MCG parameters, most values of parameters were decreased as the gap was increased. As an example, the current moment at T-wave peak reduced to 52% (at 40 mm gap), 33% (at 60 mm), and 19% (at 80 mm). However, the difference caused by the gap could be reduced by considering the distance when the MCG parameters were calculated. The study results can be used as a useful reference to design the baseline and the sensor location.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.17 no.2
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• pp.144-152
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• 2007

Diesel vehicles are a significant source of fine carbon particle emissions including polynuclear aromatic hydrocarbons (PAHs). Urinary 1-hydroxypyrene (1-OHP) is firmly established as a useful biomarker of PAHs uptake in human. To investigate the exposure effect of PAHs in miners according to using diesel truck which was for transportation of ore, we measured urinary 1-OHP as the PAHs exposure biomarker, and analyzed the relationship between urinary 1-OHP concentration and using diesel truck. The study was performed on 118 workers (56 miners in factories using diesel truck, 62 miners in factories non-using diesel truck) and 21 controls. Urine samples were obtained at the end of shift on the survey day. There was no significance in comparison with the mean concentrations on urinary 1-OHP by age, BMI, work duration, smoking, drinking and ventilation type. But significant difference were found among urinary 1-OHP concentrations on factories according to using diesel truck (p=0.000). The urinary 1-OHP mean concentration on underground miners using diesel truck ($0.54{\mu}mol/mol$ creatinine) was higher than those of surface miners using diesel truck ($0.33{\mu}mol/mol$ creatinine, p=0.028), underground miners non-using diesel truck ($0.32{\mu}mol/mol$ creatinine, p=0.001) and controls ($0.22{\mu}mol/mol$ creatinine, p=0.000). In comparison with using status diesel truck, the urinary 1-OHP mean concentration of underground miners using diesel trucks was higher than those of other mine status. The study results would be beneficial to future environmental and biological studies of PAHs exposure to diesel exhaust in mines.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.3
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• pp.286-292
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• 2016

Objectives: This study aimed to evaluate the effects of chronical exposure to high-level dusts on cellular immune function. Methods: The subjects were 110 male workers, among whom 60 were chronically exposed to high-level dusts in mica, limestone and iron mines. The remaining 50 were office workers. Ambient total, respirable dust and crystalline silica in the workplace were sampled using personal air samplers and analyzed according to NIOSH method 0500. Serum levels of hydrogen peroxide, lipid peroxide and superoxide misutase activity were measured using absorption chromatography. The subpopulations of CD4+, CD8+, natural killer cells (CD16+) and CD3+ T-lymphocytes were examined by two-color staining using monoclonal antibodies. Results: The concentration of hydrogen peroxide was significantly higher in exposed workers and superoxide dismutase activity was significantly higher in control workers. No significant difference in numbers of T-lymphocyte subpopulations were observed between exposed and control workers. A significant correlation in exposed workers was observed among total dusts, respirable dusts and crystalline silica. Hydrogen peroxide was significantly correlated with total dust (r=0.720, p<0.01), respirable dust (r=0.770, p<0.01) and crystalline silica (r=0.678, p<0.01). Concentration of hydrogen peroxide showed a significantly negative correlation with numbers of CD8+ cells (r=-0.274, p<0.01), CD3+ cells (r=-0.222, p<0.01) and natural killer cells (r=-0.556, p<0.01). Conclusions: These results suggest that chronical exposure to high-level dust affects cellular immune function and effects might mediate through reactive oxygen species and inflammatory response.

• Journal of Preventive Medicine and Public Health
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• v.28 no.1 s.49
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• pp.141-152
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• 1995

This study was performed to find out the influences of ethanol on the metabolism of trichloroethylene(TRI) in rats. TRI in corn oil at the dosage of 150, 300, 600 mg/kg was injected peritoneally once a day for two days to two groups. In one group ethanol(4 g/kg) was taken orally 30 minutes before TRI injection, and the other group ethanol was not. The results of experiments are as follows: 1. The contents of cytochrome P-450 and $b_5$ had inverse relationship with in-jected TRI amounts in both groups. 2. The activity of NADPH P-450 reductase was decreased slowly in TRI injected group related with TRI amount, but decreased drastically in the group pretreated with ethanol. 3. The activity of NADH $b_5$ reductase had relationship with injected nt amount , but the statistical significance was found only in the groups of 300 and 600 mg/kg of TRI injected without relevance to ethanol when compared with the group that was not injected. 4. The activity of ADH was more decreased and ALDH activity was more increased in groups that TRI injected and ethanol was pretreated with ethanol groups than in group without any treatment. These results suggest that ethanol may inhibit epoxide formulation, the first step of TRI metabolism, and change from TCE-OH to TCA also.

• Archives of Plastic Surgery
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• v.36 no.2
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• pp.229-232
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• 2009

Purpose: Kimura's disease is a relatively rare head and neck tumor that frequently occurs in young orientals accompanied with eosinophila. We shared our experience of two cases of Kimura's disease, treated by radical resection and post operative steroid therapy, so we report the correlation of eosinophil counts and disease progression. Methods: A 25 years old male came to the clinic with a mass localized to the right cheek inferior to the right auricle. We could not resect the mass totally. During the follow up period, we checked the eosinophil counts, and steroid therapy was started 7 months after the surgery. A 34 year old female came to the clinic with a mass localized inferior to the left auricle reaching from the posterior portion of the auricle to the left temporal portion. We tried to remove as much tumor as possible, save the temporal region, in regard to the impairment of blood supply to the auricle. After operation, steroid therapy was started. Results: In the first case, the tumor was easily approachable, and radical resection of the tumor with post operative steroid therapy was an effective treatment. In tumors located at difficult regions to remove, as in the second case, optimal debulking and post operative steroid therapy was also effective in treating Kimura's. There were no recurrences in both cases. Eosinophil counts were always reduced after surgery and steroid therapy, and during the period with low eosinophil counts, there was no recurrence of Kimura's disease. Conclusion: Surgery and post operative steroid therapy were effective in treatment of Kimura's disease, and we could assume eosinophil counts as a good indicator for evaluation of the prognosis of Kimura's disease during the follow up period.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.105-108
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• 2009

심장의 박동수 자율신경계에 있어서 매우 중요한 감성 지표가 되어 왔다. 정상인 심장박동수의 개인간 차이는 유의하게 다르지 않다. 그러나 심장병 환자는 건강한 사람들과 유의한 차이를 보이게 된다. 특히 허혈 초기에는 증상이 잘 나타나지 않기 때문에 일부러 심장에 부하를 주어서 허혈 유무를 판정하기도 한다. 부하를 주는 방법은 운동에 의한 운동부하검사, 약물에 의한 약물부하검사로 나뉜다. 신체조건 및 안정상 운동부하 검사가 불가능한 경우에는 약물을 이용한다. 심전도를 이용한 심장부하 연구는 많이 수행되어 왔으나 심자도 연구는 초기단계이다. 본 연구에서는 20 대 정상인 20 명과 협심증 환자들 27명에게 약물 부하를 유도하여 나타난 심박수, 심자도의 차이를 비교하였다. 또한 8 명의 정상인을 대상으로 가혹한 운동부하를 일으켜 최대 부하상태에선 안정 상태까지 이르는 과정을 심자도로 관찰하였다. 결과로서 운동부하 검사에서 야기되는 스트레스의 정도는 약물로 얻어지는 부하에 비해 유의하게 큼을 알 수 있었다. 또한 약물 스트레스는 정상인의 심장 전기생리학적 변화는 미미하지만 일부 허혈 환자들에게서는 유의한 차이를 보였다. 미약한 약물 스트레스에 대해 변화되는 정도가 심자도에 관찰되어 허혈 검사에 사용 가능성을 보였다.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.459-464
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• 2003

The source current distribution in a heart was reconstructed from the magnetocardiogram (MCG) and its clinical usefulness was demonstrated. MCG was measured using 40-channel superconducting quantum interference device (SQUID) gradiometers for a patient of Wolff-Parkinson-White (WPW) syndrome, which has an accessory pathway between the atria and the ventricles. Reconstruction of source current distribution in a plane below the chest surface was performed using minimum norm estimation (MNE) algorithm and truncated singular value decomposition (SVD), In the simulation, we confirmed that the current distributions. which were computed for the test dipoles, represented well the essential feature of the test current configurations, In the current map of WPW syndrome, we observed abnormal currents that would bypass the atrioventricular junction at a delta wave. However, we could not observe such currents any more after the surgery. These results showed that the obtained current distribution using MCG signals is consistent with the electrical activity in a heart and has clinical usefulness.

• Analytical Science and Technology
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• v.27 no.5
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• pp.248-253
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• 2014

This study aimed to evaluate the effects of exposure to manganese (Mn) and lead (Pb) on immune system. The subjects were 42 male workers, among whom 13 office workers (Group I) had never been occupationally exposed to heavy metals, 21 were worked in manufacturing factories (Group II) and 8 were welders (Group III). The mean blood Mn and Pb level by groups were significantly different. The numbers of CD19+ and total lymphocytes in Group I were significantly higher than those in other groups, but no significant differences were found in other T lymphocytes subpopulation. Mn and Pb concentrations showed negative correlation with T lymphocytes subpopulation, but Mn concentrations were statistical significances with T lymphocytes subpoplation except CD4+CD45RO+ and natural killer cell. Pb concentration was only statistical significance with total lymphocytes. Our results suggest that occupationally exposed to Mn and Pb can affect the cellular immune response.

• Journal of Biomedical Engineering Research
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• v.24 no.3
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• pp.159-165
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• 2003

We developed a 37-channel magnetoencephalogram (MEG) measurement system based on low-noise superconducting quantum interference device (SQUID) magnetometets, and operated the system to measure MEG signals. By using double relaxation oscillation SQUIDs with high flux-4o-voltage transfers, the SQUID outputs could be measured directly by room temperature preamplifiers and compact readout circuits were used for SQUID operation. The average field noise level of the magnetometers is about 3 fT/√Hz in the white region, low enough for MEG measurements when operated inside a magnetically shielded room. The 37 magnetometers were distributed on a hemispherical surface haying a radius of 125 mm. In addition to the 37 sensing channels. 11 reference channels were installed to pickup external noise and to form software gradiometers. A low-noise liquid helium dewar was fabricated with a liquid capacity of 30 L and boil-off rate of 4 L/d. The signal processing software consists of digital filtering, software gradiometer, isofield mapping and source localization. By using the developed system, we measured auditory-evoked fields and localized the current dipoles, demonstrating the effectiveness of the system.

• Journal of the Korean GEO-environmental Society
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• v.4 no.1
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• pp.19-28
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• 2003

Current methods for lateral thrust calculations are based on the classical formulations of Rankine or Coulomb. However, the previous studies indicate that lateral earth pressures acting on the wall stem, which is the function of deformation parameters of the backfill, are close to the active condition only in the top half of the wall stem and in the lower half of the wall stem, the lateral earth pressures are significantly in excess of the active pressures. This paper presents the compressible inclusion function of EPS which can results in reduction of static earth pressure by accomodating the movement of retained soil. A series of model tests were conducted to evaluate the reduction of static earth pressure using EPS inclusion and determine the optimum stiffness of EPS. Also, field test was conducted to evaluate the reduction of static earth pressure using EPS inclusion. Based on field test it is found that the magnitude of static earth pressure can be reduced about 20% compared with classical active earth pressure.