• Journal of the Korean Society of Visualization
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• v.21 no.1
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• pp.67-73
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• 2023

In the study, pool boing critical heat flux (CHF) was experimentally investigated depending on the length of heaters. A smooth silicon oxide surfaces are used as the boiling surfaces. As the results of pool boiling experiments based on distilled water in ambient pressure condition, the CHF decreased as the length of the heater increased. By the high speed imaging, it was shown that the number of vapor columns increased as the length of the heater increased. Comparing the number of vapor columns and the CHF according to the heater length, the change in the CHF according to the heater length was analyzed based on the hydrodynamic instability.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.126-133
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• 2023

Objectives: This study was conducted to find out the prevalence and risk factors of anemia according to shift work. Methods: Data from the Korean National Health and Nutrition Survey (2016-2020) were used. 9,787 workers were divided into shift workers and non-shift workers. The work type between 6AM-6PM was defined as day work, and other work types were defined as shift work. A chi-square test was used to indicate the distribution of risk factors expected to affect shift work in both frequency and percentage. Multiple logistic regression analysis was performed to find out the relationship between anemia prevalence and shift work. Results: As a result of analysis, multiple logistic regression analysis of anemia prevalence and shift work, the OR (95% CI) of male workers on shift work was 2.186 (1.139 to 4.194) and there was a statistically significant difference. Conclusions: In conclusion, anemia in male shift workers should be considered a possibility of health problems. In the future, research based on various data collection should be conducted for research to reveal various causes or diseases of anemia in the future.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.285-286
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• 2023

우리 나라는 오래 전부터 민방위 차원에서 각 지역에 대피소를 선정해두고 정부 해당 부처의 게시판으로 알리고 있다. 그러나, 민방위 훈련이 거의 실시되지 않는 터라 대부분의 국민들은 어느지역에 어떤 대피소가 마련되어 있는지 알지 못한다. 최근에는 민방위 뿐만 아니라 바닷가 해일에 대비하기 위한 대피소도 늘어나고 있는데 이를 알고 있는 국민 또한 많지 않다. 따라서 이 연구에서는 현재 위치 주변에 어떤 대피소가 있는지와 가장 가까운 대피소까지의 길을 안내하는 긴급 대피소 안내 앱을 개발한다. 그 외에 이 앱은 지역별로 최근 발송된 재난 문자를 검색하는 기능도 제공한다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.204-212
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• 2019

The optimal application rate of a controlled release fertilizer (CRF) on the growth, yield, and seeding time of rice grown on seedling trays was investigated. The experimental field was located at $37^{\circ}22^{\prime}10^{{\prime}{\prime}}N$ latitude and $127^{\circ}03^{\prime}85^{{\prime}{\prime}}E$ longitude in Hwaseong, Gyeonggi-do, Republic of Korea. The soil in the paddy field was a clay loam. The CRF used in the experiment contained $300g\;kg^{-1}$ of nitrogen, $60g\;kg^{-1}$ of phosphate, and $60g\;kg^{-1}$ of potassium, respectively. The CRF was applied at the rate of 0, 200, 300, 400, 500, and 600 grams on rice seedling tray compared with the field application based on soil testing (control), respectively. The CRF can be applied as single application(which can replace basal fertilizer application and two top dressing application) directly to the seedling tray, and showed the minimum release at the seedling period. Considering the plant growth, nitrogen use efficency and yield of rice, the optimal application rate of developed CRF was 500 g per seedling tray and the yield of rice at this application rate was $4.92{\sim}5.04Mg\;ha^{-1}$. The regression formula between the rice yield and application rates of CRF was as follows ; "$Y=0.0002{\chi}^2+0.0963{\chi}+411.6$($R^2$ : 0.9922) in 2010 and $Y=8E-6{\chi}^2+0.2723{\chi}+344.04$($R^2$:0.9864) in 2011, Y : Rice yield ($Mg\;ha^{-1}$), ${\chi}$ : Application rate (grams) of controlled release fertilizer". The optimum application rates of CRF per rice seedling tray by regression formula was 498 grams in 2010 and 513 grams in 2011.

• Journal of Ocean Engineering and Technology
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• v.23 no.2
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• pp.53-57
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• 2009

Unmanned surface vehicles (USVs) conduct various missions while exchanging information with control centers. Maritime security, coastal surveillance, and sea surface and undersea inspections are included in the important missions of USVs. To carry out these missions, large amounts of information are required from sensors, such as cameras, radars, and sonars. High bandwidth wireless communication is necessary to send this information to the control center in real time. In general, USVs are made using small boats. The motions of small boats are easily influenced by sea waves and the magnitude of changes in the attitude is large and the period of the changes is short in comparison with large ships. Thus, the direction of an antenna beam pattern for a wireless communication system in a USV can change rapidly, and with a large magnitude. In addition, since the reflection of electromagnetic waves on the sea surface is not negligible, the effect of multipath noises on the wireless communication system must be considered carefully. There are also several other elements that negatively affect wireless communication systems in USVs. This paper presents the wireless communication environment to be considered in the design and implementation of wide bandwidth communication systems for USVs. Short test results for wireless communication on the sea are also given.

• Annals of Clinical Neurophysiology
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• v.2 no.2
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• pp.89-94
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• 2000

Purpose : Carpal tunnel syndrome (CTS) is a disorder of median nerve at wrist. It is usually diagnosed through clinical manifestation and nerve conduction study (NCS). However, sometimes, NCS does not provide a reliable evidence to reach the diagnosis. Thus, authors performed this study to determine whether NCS was correlated with specific parameters measured on magnetic resonance imaging (MRI) which might become a potential complemental diagnostic tool. Methods : We performed MRI in 34 wrists of 18 patients with clinical manifestations of CTS and pathologic nerve conduction values and analyzed them at levels of the distal radioulnar joint, pisiform and hook of hamate, Results : Increase in the cross-sectional area of the median nerve at the pisiform level and flattening, increased signal intensity, and contrast enhancement of the median nerve at levels of the pisiform and hook of hamate were statistically significant. Change in cross sectional areas between the distal radioulnar joint and hamate and the signal intensities at levels of pisiform and hamate were well correlated with the median nerve conduction velocity. Conclusions : Characteristic MRI findings in CTS reported previously were well demonstrated and some of MRI parameters are well correlated with nerve conduction study. MRI, despite cost, may help in evaluating CTS.

• Health Policy and Management
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• v.30 no.3
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• pp.418-429
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• 2020

Background: This study aims to analyze the cost and the length of stay (LOS) of acute myocardial infarction (AMI) patients with coronary artery stenting according to the characteristics of individuals and institutions. Methods: The data was collected from Korean National Health Insurance Service's customized database in 2010 and 2015. Chi-square test, t-test, analysis of variance, and multilevel analysis were performed. Results: The intraclass correlation coefficients for cost were 7.02% in 2010, 5.61% in 2015 and for LOS were 3.17%, 1.40%, respectively. The average costs were 9,067,000 won in 2010 and 9,889,000 won in 2015 (p<0.0001). However, the cost in 2015 was lower than the cost applying increased fee. The costs increased in aged 50-59 years, 60-69 years, and aged ≥70 years versus in aged under 49 years. The cost was higher in Charlson comorbidity index (CCI) 3 to 4 and ≥5 than in CCI 0. The costs were lower in male, medical aid recipients, metropolises, and local hospitals in other regions in 2010. LOS decreased from 8.1 days in 2010 to 7.4 days in 2015. It decreased in male, high income group, and the group of admission via emergency room. However, it increased in higher ages and medical aid recipients, and it also increased when CCI rose. The Internal Herfindahl Index was related to LOS in 2010. Conclusion: The variation of hospital level was small compared to the patient level. Therefore, it is important to implement applicable policies at the patient level in order to reduce cost and LOS of AMI patients.

• Journal of Korean Neurosurgical Society
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• v.60 no.6
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• pp.755-762
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• 2017

Objective : The purpose of this study is to describe the detailed surgical technique and short-term clinical and radiological outcomes of lateral lumbar interbody fusion (LLIF) and in situ lateral screw fixation using a conventional minimally invasive screw fixation system (MISF) for revision surgery to treat rostral lumbar adjacent segment disease. Methods : The medical and radiological records were retrospectively reviewed. The surgery was indicated in 10 consecutive patients with rostral adjacent segment stenosis and instability. After the insertion of the interbody cage, lateral screws were inserted into the cranial and caudal vertebra using the MISF through the same LLIF trajectory. The radiological and clinical outcomes were assessed preoperatively and at 1, 3, 6, and 12 months postoperatively. Results : The median follow-up period was 13 months (range, 3-48 months). Transient sensory changes in the left anterior thigh occurred in 3 patients, and 1 patient experienced subjective weakness; however, these symptoms normalized within 1 week. Back and leg pain were significantly improved (p<0.05). In the radiological analysis, both the segmental angle at the operated segment and anterior disc height were significantly increased. At 6 months postoperatively, solid bony fusion was confirmed in 7 patients. Subsidence and mechanical failure did not occur in any patients. Conclusion : This study demonstrates that LLIF and in situ lateral screw fixation may be an alternative surgical option for rostral lumbar adjacent segment disease.

• Korean Journal of Medicinal Crop Science
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• v.20 no.4
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• pp.270-276
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• 2012

This study was performed to enhance contents of low molecular weight ginsenoside Rh2 and Rg3 using an ultra high pressure and steaming process in wild cultured-Root in wild ginseng. For selective increase in contents of Rg3 and Rh2 in cultured wild ginseng roots, an ultra high extraction was applied at 500MPa for 20 min which was followed by steaming process at $90^{\circ}C$ for 12 hr. It was revealed that contents of ginsenosides, Rb1, Rb2, Rc and Rd, were decreased with the complex process described above, whereas contents of ginsenoside Rh2 and Rg3 were increased up to 4.918 mg/g and 6.115 mg/g, respectively. In addition, concentration of benzo[${\alpha}$]pyrene in extracts of the cultured wild ginseng roots treated by the complex process was 0.64 ppm but it was 0.78 ppm when it was treated with the steaming process. From the results, it was strongly suggested that low molecular weight ginsenosides, Rh2 and Rg3, are converted from Rb1, Rb2, Rc, and Rd which are easily broken down by an ultra high pressure and steaming process. This results indicate that an ultra high pressure and steaming process can selectively increase in contents of Rg3 and Rh2 in cultured wild ginseng roots and this process might enhance the utilization and values of cultured wild ginseng roots.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.952-964
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• 2016

The prototype generation IV sodium-cooled fast reactor (PGSFR) has been developed by the Korea Atomic Energy Research Institute. This reactor uses sodium as a reactor coolant to transfer the core heat energy to the turbine. Sodium has chemical characteristics that allow it to violently react with materials such as a water or steam. When a sodium-water reaction (SWR) occurs due to leakage or breakage of steam generator tubes, high-pressure waves and corrosive reaction products are produced, which threaten the structural integrity of the components of the intermediate heat-transfer system (IHTS) and the safety of the primary heat-transfer system (PHTS). In the PGSFR, SWR events are included in the design-basis event. This event should be analyzed from the viewpoint of the integrities of the IHTS and fuel rods. To evaluate the integrity of the IHTS based on the consequences of the SWR, the behaviors of the generated high-pressure waves are analyzed at the major positions of a failed IHTS loop using a sodium-water advanced analysis method-II code. The integrity of the fuel rods must be consistently maintained below the safety acceptance criteria to avoid the consequences of the SWR. The integrity of the PHTS is evaluated using the multidimensional analysis of reactor safety-liquid metal reactor code to model the whole plant.