• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.1
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• pp.27-44
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• 1993

This study was performed to investigate the changes of mandibular condyle by low calcium diet and the effects of irradiation on the bone in osteoporotic state. In order to carry out this experiment, 80 seven-week old Sprague-Dawley strain rats weighing about 150 gm were selected and equally divided into one experimental group of 40 rats and one control group with the remainder. The experimental group and the control group were then subdivided into two group and exposed to irradiation. The two irradiation groups received a single dose of 20 Gy on the jaw area only and irradiated with a cobalt-60 teletherapy unit. The rats in the control and experimental groups were serially terminated by fours on the 3rd, the 7th, the 14th, and the 21st day after irradiation. After termination, both sides of the dead rats mandibular condyle were removed and fixed with 10% neutral formalin. The bone mineral density of mandibular condyle was measured by use of dual energy X-ray bone densitometer(model DDX-alpha, Lunn Corp., U. S. A.). The mandibular condyle was radiographed with Hitex HA-80(Hitex Co., Japan). Thereafter, the obtained radiographs were observed, and the mandibular condyle was further decalcified and embedded in paraffin as the general method. The specimen sectioned and stained with hematoxylin-eosin, PAS and Rabbit Anti-Human Tumor Necrosis Factor-a observed by a light microscope. The obtained results were as follows: 1. In the non-irradiated group with the low calcium diet, the bone mineral density of the condyle was markedly decreased after 14 days, and decrease the number of trabeculae of the condyle and resorption of the calcified cartilaginous zone were observed after 3 days. On microscopic observations, the number nd size of trabeculae were decreased after 7 days of experiment. 2. In the irradiated group with the low calcium diet, the bone mineral density of the condyle was markedly decreased after 14 days and resorption of the calcified cartilaginous zone and decrease the number and coarse of the trabeculae of the condyle were observed. These findings were extended rather than in non-irradiated group with low calcium diet. On microscopic observations, many osteoclasts were detected and the number and size of trabeculae were somewhat decreased after 7 days. Also there was degenerative changes of tissues of bone marrow on the 14th day but that condition was restored on the 21st day of experiment. 3. In the irradiated group with normal diet, the bone mineral density of the condyle was somewhat decreased with times and degree of decrease of the number of trabeculae was somewhat larger than in the non-irradiated group with normal diet. On microscopic observations, the tissues of bone marrow were atrophic and degenerative changes but that condition was restored on the 21st day of experiment. 4. In immunocytochemical findings, in the irradiated and non-irradiated groups with low calcium diet, negative or partial positive response to TNF was observed, but positive response in the normal diet groups.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.31 no.2
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• pp.31-42
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• 2013

A purpose of this study, after identifying the status and type of changes derived elements that make up the Seowon(書院); landscape space and the space of the during the recent World Heritage, focusing promote the newly introduced trees listed in the important value, authenticity and integrity aspects The results can be summarized as follows. The results can be summarized as follows. Appeared trees in various old documents are 10 species; Prunus persica (L.) Batsch, Prunus mume(Siebold) Siebold & Zucc., Salix koreensis Andersson. The planting space shows regularity of some degree depends on the status of the species, essentially 3 types of Juniperus chinensis L., Lagerstroemia indica L., Phyllostachys nigra(Lodd.) Munro are primarily located in inside of seowon(書院), Zelkova serrata (Thunb.) Makino., Salix koreensis Andersson is in out side of seowon(書院). 5 types of location space to species such as Juniperus chinensis L., Ginkgo biloba L. species are the most frequently appear and it can be national representative trees. Plants which have limited vitality is a factor to prove a history of seowon(書院), it is accord with authenticity aspects that it gives meaning of symbolic to canonized figure's preference Maintenance work carried out over the years has damaged to origin of tree and thoughtlessly planted without having to go through a thorough historical research has resulted in weakening the presence of the essential space. It should preserve to features originally it have is figure reflect the viewpoint of the transformed current private to reveal the history of the various places. In conclusion, this research continues to study at the spatial dimension like a building in limited to panted, and also determine the intrinsic value of the overall spatial configuration.

• Environmental and Resource Economics Review
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• v.25 no.2
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• pp.199-228
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• 2016

This study investigates the effects of economic factors and forest environments on rural residential area development in seven north central states of the U.S. by focusing on the relative importance of not only economic factors but also forest environments by forest type as core drivers of residential development. An empirical model of locations and magnitudes of population changes since 1950 in the north central region is first constructed, and then a panel model with fixed effects for counties is used to explain population growth by age group over time at the county level. Then a set of three equations is estimated for three major age groups, and a cross-sectional model is estimated for the last time period that regresses county-level environmental amenity variables on fixed effects coefficients for counties. Finally, an equation explaining changes in rural housing density is estimated. The results imply that immigrant age is a key factor influencing the choice of the place of residence and that the effects of environmental amenity factors on population growth and subsequent housing development in a county vary according to the age group.

• Journal of Trauma and Injury
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• v.25 no.4
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• pp.166-171
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• 2012

Purpose: In patients with traumatic hemoperitoneum or pelvic bone fracture who underwent angiography and embolization, we want to find the prognostic factors related with mortality. Methods: Patients(333 patients) who visited our hospital with traumatic injury from March 2008 to April 2012 were included in this study. Only 37 patients with traumatic hemoperitoneum or pelvic bone fracture underwent angiography and embolization. A retrospective review was conducted, and Glasgow coma scale (GCS), Revised trauma score (RTS), Injury severity score (ISS), initial laboratory finding and time interval, the amount of transfusion from the arrival at the ER to the start of embolization, and the vital signs before and after procedure were checked. Stastical analysis was conducted using the Chi square and Mann-Whitney U test. Results: In univariate analysis, the amount of transfusion, the base deficit before procedure, the systolic blood pressure before and after the procedure, the GCS, the RTS and the ISS were significantly associated with prognosis. In the multivariate analysis, the ISS and the base deficit had significant association with prognosis. Of the 37 patients who underwent angiography and embolization, 31 patients needed not additional procedure (Group A) while the other 6 patients needed an additional procedure (Group B). After procedure, a statistically significant higher blood pressure was observed in Group A than in Group B. As to the difference in blood pressure before and after the procedure, a statistically significant decrease in systolic blood pressure was observed in Group B, but an increase was observed in Group A. Conclusion: In traumatic hemoperitoneum or pelvic bone fracture patients who underwent angiography and embolization, GCS, ISS, RTS, transfusion amount before the procedure, initial base deficit and systolic blood pressure were factors related to mortality. When patients who underwent angiography and embolization only were compared with patients who underwent re-embolization or additional procedure after the first embolization, an increase in systolic blood pressure after embolization was a prognostic factor for successful control of bleeding.

• Journal of Korean Society of Transportation
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• v.25 no.1 s.94
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• pp.93-105
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• 2007

To raise transit ridership, it is necessary to expand transit facilities in long term Plans and to raise passengers' satisfaction by improving bus service qualify in short term Plans. In this study, the relationship between bus driver job satisfaction and Passenger service Performance is analyzed. The results of the study indicate that a driver s job satisfaction has an influence on accident rates. However, even when job satisfaction is not very high, if food resting facilities and Policies ave Provided then the Probability of an accident tends to decrease. To improve job satisfaction, several things should be done, such as stabilizing employment, creating fair company policies, improving overall employee welfare, and enhancing driver achievement from working. The satisfaction from salary is also an important factor and drivers are satisfied when they earn more money relative to other companies' drivers and when they aye satisfied with their salary increases. Therefore, creating appropriate monetary incentives would be a food policy for improving bus driver job satisfaction. This study serves as pilot research to make a foundation for further research about job satisfaction in the public transit field.

• Biomolecules & Therapeutics
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• v.8 no.2
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• pp.140-146
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• 2000

Recently, we reported that immunostimulation of primary rat cortical astrocyte caused stimulation of glucose deprivation induced apoptotic cell death. To enhance the understanding of the mechanism of the potentiated cell death of clucose-deprived astrocyte by immunostimulation, we investigated the effect of immunostimulation on the glucose deprivation induced cell death of rat C6 glioma cells. Co-treatment of C6 glioma cells with lipopolysaccharide (LPS, $1\;{\mu}\textrm{g}/ml$) and interferon ${\gamma}(IFN{\gamma},\;100U/ml)$ is serum free condition caused marked elevationo f nitric oxide production ($>50\;{\mu}M$). In this condition, glucose deprivation caused significant release of lactate dehdrogenase (LDH) from C6 glioma cells while control cells did not show LDH release. To investigate whether elevated level of nitric oxide is responsible for the enhanced LDH release in glucose-deprived condition, C6 glioma cells were treated with 3-morphorinosydnonimine (SIN-1) and it was observed that SIN-1 caused increase in LDH release from glucose-deprived C6 glioma cells. Treatment of C6 glioma cells with $25\;{\mu}M$ of pyrrolidinedithiocarbamate (PDTC) which inhibit Nuclear factor kB (NF-kB) activation, caused complete inhibition of nitric oxide production. Treatment of C6 glioma cells with NO synthase inhibitors, $N^{G}$-nitro-L-arginine (NNA) or L-$N{\omega}$-nitro-L-arginine methyl ester (L-NAME), caused inhibition of nitric oxide production and also glucose deprivation induced cell death of cytokine-stimulated C6 glioma cells. In addition, diaminohydroxypyrimidine (DAHP, 5 mM) which inhibits the synthesis of tetrahydrobiopterine (BH4), one of essential cofactors for iNOS activity, caused complete inhibition of NO production from immunostimulated C6 glioma cells. The results from the present study suggest that immunostimulation causes potentiation of glucose deprivation induced death of C6 glioma cells which is mediated at least in part by the increased production of nitric oxide. The vulnerability of immunostimulated C6 glioma cells to hypoglycemic insults may implicate that the elevated level of cytokines in various ischemic and neurodegenerative diseases may play a role in their pathogenesis.

• Journal of Preventive Medicine and Public Health
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• v.26 no.1 s.41
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• pp.20-36
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• 1993

Work-related low back pain is one of the major factors that cause the loss of working power especially in actively working age, therefore controlling the work-related low back pain is one of the major issues in the field of industrial safety and health. This study was performed for detecting the risk factors and proposing the efficient control program of the work-related low back pain. The subjects were male workers employed at the manufacturing industry in Pusan with longer than 6 months' working duration. The data was collected by self-reported questionnaire and interview from May 1 to October 31,1992. The contents of questionnaire were as follows:. the experience of low back pain within the recent one month, general characteristics(age, marital status, education level, religion, regular exercise), physical characteristics(height, weight), employment status(working duration, daily working hours, rest during work, satis(action fur the job), type of work and working environments(posture, forward bending, lifting and movement, satisfaction for table and chair). The result was analyzed for 608 entire respondents by case-control comparative method. The number of cases was 152 with a history of work-related low back pain, so the relative frequency of self-reported work-related low back pain was 25.0%, and the number of controls was 344 without any history of low back pain. As a result, two characteristics of the employment status(working duration, satisfaction fur the job) and all characteristics of type of work and working environments showed a statistical significance between the case and control groups(p<0.01). The Oddb ratios of these variables for Work-related low back pain were calculated. They were 7.88 for the satisfaction fur chair, 7.86 for lifting and movement,3.31 for satisfaction for table, and 2.22 fur bending forward(p<0.01). And for the multivariate logistic regression analysis confirmed that unsatisfaction for table was independent risk factor for Work-related low back pain. In summary, though this study was based upon the self-reported questionnaire and the subjective complaints, the satisfaction for chair, lifting and movement, satisfaction for table, and bending forward concerned with the type of work and working environments were considered as the main factors causing the work-related low back pain, and the work-related low back pain may be preventable by the ergonomic control of these factors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1337-1345
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• 2011

In pressurized water reactors (PWRs), the reactor pressure vessel (RPV) upper head contains numerous control rod drive mechanism (CRDM) nozzles. In the last 10 years, the incidences of cracking in alloy 600 CRDM nozzles and their associated welds has increased significantly. Several axial and circumferential cracks have been found in CRDM nozzles in European PWRs and U.S. nuclear power plants. These cracks are caused by primary water stress corrosion cracking (PWSCC) and have been shown to be driven by welding residual stresses and operational stresses in the weld region. Therefore, detailed finite-element (FE) simulations for the Korea Nuclear Reactor Pressure Vessel have been conducted in order to predict the magnitudes of the weld residual stresses in the tube materials. In particular, the weld residual stress results are compared in terms for nozzle location, geometry factor$r_o$/t, geometry of fillet, and adjacent nozzle.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.591-591
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• 2012

본 연구는 Transparent conducting oxide (TCO, 산화물투명전극)를 이용한 박막태양전지 효율향상에 관한 것으로, 이중의 TCO층(Double-stacked TCO layer)의 효과적인 광학 및 전기적 설계에 관한 것이다. 기존 박막 태양전지에서는 투명전극 TCO layer로서, ITO (Indium-Tin-Oxide), FTO (Fluorine- Tin-Oxide), 및 AZO(Aluminum-doped Zinc Oxide) 등을 사용해 왔다. 각 TCO layer마다 장점이 있지만 단점 또한 존재한다. ITO의 경우 높은 전기적 특성을 가지는 반면 수소 플라즈마에 취약하고 기계적 강도에 취약해 ITO 단일층만으로 박막 태양전지에 적용하는 것에 제한을 받는다. 한편, AZO의 경우 전기적 특성도 우수할 뿐만 아니라 수소 플라즈마에도 내구성이 강한 장점이 있지만, 일함수가 p형 반도체보다 낮아 Schottky junction이 되어, 높은 전위장벽이 형성된다. 이는 정공의 이동을 방해하고, 정공의 축적이 일어나서 순방향 전압을 인가할 때 많은 전류의 감소를 가져온다. 또한, AZO와 p형 반도체 사이의 높은 직렬저항으로 인해 광전압(Voc, Open circuit voltage)와 충실률 (FF, Fill factor)가 떨어진다는 단점이 있다. 본 실험에서는 ITO/AZO 2중구조의 TCO층을 적용하여 상기의 문제점을 해결하고자 한다. 이중 구조 TCO층은 Magnetron sputter system을 이용하여, 단계적으로 증착되었다. 빛이 입사하는 유리에 ITO를 제1전도층으로 증착하였는데, ITO는 입사광의 투과도와 전기전도성이 우수하다. 제2전도층으로는 AZO층을 이용하였으며, 실리콘 반도체층과 접하게 된다. AZO는 실리콘 증착시 발생하는 수소 플라즈마에 안정적이고, 물리적 강도 또한 우수한 장점이 있다. 이중 구조층위에 실리콘 광흡수층(Si absorber)을 증착하였으며, pin 구조를 가진다. 기존, 단일막 TCO층과 2중구조 TCO층을 이용하여, 실리콘 박막 태양전지를 구성하였다. 이때, ITO/AZO의 2중구조를 적용하였을 때 태양 전지 특성이 크게 향상된 결과를 얻을 수가 있었다. 특히, 전류밀도의 경우 ITO, FTO, AZO 각각 14.5 mA/cm2, 11.2 mA/cm2, 8.18 mA/cm2를 나타낸 반면 ITO/AZO 2중구조의 경우 약 17mA/cm2 로 크게 향상 되었고, 태양전지 변환 효율도 각각 7.5%, 6.9%, 4%에서 ITO/AZO 2중 구조의 경우 8.05%로 크게 향상되었다. 본 발표에서는 2중구조 TCO를 이용한 현공정에 적용 가능한 박막태양전지 효율향상 기법에 대해 논의하고자 한다.

• Journal of Food Hygiene and Safety
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• v.25 no.2
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• pp.143-147
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• 2010

Chronic exposure to Arsenic (As) causes significant human health effects including various cancers. Total As concentrations from 300 polished rice samples cultivated near the mining areas in Korea were analyzed to estimate a probabilistic assessment of human health risk from As-contaminated rice. The mean of total As concentrations in rice was 0.09 mg/kg and lognormal distribution model was set for total As concentrations. Human health risk for As in rice was estimated using gender-specific rice consumption data and average daily dose (ADD). While cancer risk (CR) and hazard quotient (HQ) were calculated using oral cancer slope factor (OCSF) and Reference dose (RfD) suggested by the U.S. EPA. Mean of CR posed by total As was 2.16 (for male) and 1.83 (for female) per 10,000. The HQ for general population from rice cultivated near the mining areas in Korea was below 1 as the $50^{th}$ percentile of general population. However, less than 10% of general population consuming rice cultivated near the mining areas would exceed 1.0. This result is similar with those from each gender-specific group.