• Journal of the Korean Society of Radiology
• /
• v.12 no.7
• /
• pp.801-806
• /
• 2018

Germanium crystals have a dead layer that causes efficiency deterioration because the layer is not useful for detection but strongly weakens the photons. Thus, when the data provided by the manufacturer is used in the detector simulation model, there is a slight difference between the calculated efficiency and the measured efficiency.The shape and dimensions of the high purity germanium (HPGe) detector were determined by CT scans to accurately characterize the shape for the Monte Carlo roll simulation. It is found that the adjustment of the dead layer is a good match with the relative deviation of ${\pm}3%$ between the measurement efficiency and the simulation efficiency at the energy range of 50 - 1500 keV. Simulation data were compared by varying the thickness of the dead layer. The new Monte Carlo simulations were compared with the experimental results to obtain new blank layer thicknesses. The difference in dead layer results for the 1.5 mm thick end cap simulation model in 1.4 and 1.6 mm thick End Cap simulation models was a systematic error due to the accuracy of the end cap dimensions. After considering all errors including statistical errors and systematic errors, the thickness of the detector was calculated as $1.02{\pm}0.14mm$. Therefore, it was confirmed that the increase in the thickness of the dead layer causes the effect to be effected on the efficiency reduction.

• Journal of the Korean Institute of Gas
• /
• v.23 no.4
• /
• pp.1-9
• /
• 2019

Large-scale industrial boilers operating at high temperature and high pressure, have a large amount of water, and a large amount of energy is released at the time of explosion. Currently, most industrial boilers use gas fuel such as LNG and LPG, etc. and fuel exists in the same space as equipment, so there is a high possibility of secondary damage such as fire or explosion in the event of a boiler accident. Both special care and management are required to operate the very dangerous equipment that causes casualty 2.51 per accident. For boilers of a certain size or more, the Korea Energy Agency conducts inspections in accordance with the Energy Usage Rationalization Act, KS, and public notice of the Ministry of Industry, Trade and Resources. In this research, based on the results of the inspection, the hazard factorss are configured, and a questionnaire is conducted to the inspector, the equipment manager, the maintenance person, and the person in charge of the manufacturer. We analyzed the results by using AHP (Analytic Hierarchy Process). As a result of analysis, generally recognized hazard factorss are not good management, measurement failure, specification failure, water leak, leak analysis, but connection, welding, scale, and corrosion, etc. are relatively less important. It is judged that the adverse factors that are recognized to be highly important among all groups and careers are already well managed, but less important and adverse factors should be well managed to ensure that the safe usage of the boiler.

• 재활복지
• /
• v.17 no.4
• /
• pp.339-370
• /
• 2013

This study is to suggest necessary improvements of inconvenient elements as well as the ergonomic design standard to develop disabled cars by evaluating the types of needs and observing the behavior characteristics on their car use and the survey on the complaints of the disabled drivers and their guardians in the use of disabled car. The results of this study are as follows. First, both the disabled drivers and their guardians are found to feel high inconvenience and low satisfaction with the cars they use now. Second, the disabled owner-drivers also answered in a same way as guardians. They find the most difficulty in moving the supporting equipment to get into and out of a car. Both the owner-drivers with disabilities and guardians complained of lack of handiness they face when they wear the seat belts and sitting on the seats. In view of this, a disabled car to be developed should have ergonomic design for its seats and the safety of the seatbelt as well as trouble-free supporting equipment helping them move. Third, rather than owner-drivers with handicaps, guardians expressed more difficulties and less contentment with the cars for the disabled, which is reckoned to lead to the changes of perspectives on development of cars for the disabled breaking away from existing viewpoints focusing on the accessibility to the vehicles. Fourth, both owner-drivers and guardians showed higher interests in driving and other safety and convenience measures than in using supporting equipment to get into and out of vehicles, implying that rather than the accessibility to get into and out of a car, convenience should primarily be taken into account for the design of the disabled car. Fifth, the auto-manufacturer is to give prior thought to user convenience when developing a car in practice. For this, the developer may have the disabled car users join the process of development as well as asking experts for help and participation.

• International Area Studies Review
• /
• v.20 no.2
• /
• pp.25-46
• /
• 2016

In order to newly expand and define the concept of "strategic servitization" based on Industry 4.0, this study tried to evaluate the existing status of domestic and foreign servitized manufacturing and investigated the servitization cases of some leading overseas companies. In addition, we chose 250 samples of manufacturing firms listed on KOSDAQ and collected a vast amount of data regarding servitized manufacturing, such as the current status about new businesses, profit model, and financial fluctuations of each company. Based on these data, we classified the main types of manufacturing-service convergence into a $2{\times}2$ framework and derived a new strategic servitization model for each type of signature. Furthermore, we divided the sample corporations into three groups, which are pure manufacturer, servitized firm, and strategic servitized firm, and through the mutual comparison of the real sales amounts and the estimated sales amounts by time-series extrapolation analysis, we statistically proved that the service sales of strategic servitized firms give positive impacts on ROA when compared with those of the other two groups. Finally, we selected 12 leading domestic strategic-servitized firms, interviewed them in depth, and not only organized the issues during this process and their solutions by categories but also suggested the policy demands for strategic servitization.

• Journal of the Korean Society of Urban Environment
• /
• v.18 no.4
• /
• pp.401-408
• /
• 2018

EQPS (Effluent Quality Prediction System, Dynamita, France) was applied to analyze the appropriateness of the design of a bioreactor in A sewage treatment plant. A sewage treatment plant was designed by setting the design concentration of the secondary clarifier effluent to total nitrogen and total phosphorus, 10 mg/L and 1.8 mg/L, respectively, in order to comply with the target water quality at the level of the hydrophilic water. The retention time of the 4-stage BNR reactor was 9.6 hours, which was 0.5 for the pre-anoxic tank, 1.0 for the anaerobic tank, 2.9 for the anoxic tank, and 5.2 hours for the aerobic tank. As a result of the modeling of the winter season, the retention time of the anaerobic tank was increased by 0.2 hours in order to satisfy the target water quality of the hydrophilic water level. The default coefficients of the one step nitrification denitrification model proposed by the software manufacturer were used to exclude distortion of the modeling results. Since the process modeling generally presents optimal conditions, the retention time of the 4-stage BNR should be increased to 9.8 hours considering the bioreactor margin. The accurate use of process modeling in the design stage of the sewage treatment plant is a way to ensure the stability of the treatment performance and efficiency after construction of the sewage treatment plant.

• Journal of the Korean Data Analysis Society
• /
• v.20 no.6
• /
• pp.3087-3099
• /
• 2018

Due to the constant changes of companies' global networks, the expansion of global e-commerce as well as the market-oriented global supply chain management, global enterprises are strategically selecting and entering into viable countries able to become global footholds. Therefore, this study aims to scrutinize the trend of changes in the global networks of Korean companies by analyzing the current overseas countries over the past decade. From the analysis, it has been found that there is a significant difference in the priorities of targeting countries among shipping, manufacturing and logistics companies. Logistics companies preferred to enter Germany first while they attached to a lower priority to Singapore. Manufacturing companies had a lower priority to advance to India, while they preferred to advance to Mexico; however, shipping companies were analyzed to prefer to enter the US. In addition, all of these companies identified the importance of securing volume and network by entering overseas markets to achieve economies of scale and scope and to maintain global competitiveness. Joint overseas expansion of manufacturers with shipping and logistics companies can be recommended to facilitate the entry and thus, enhance global competitiveness and service capabilities and also secure new growth engines.

• Journal of the Korean Solar Energy Society
• /
• v.39 no.1
• /
• pp.59-66
• /
• 2019

BIPV or BAPV installation applied to building is increasing through public utility mandates enterprise. Solar PV energy generates only during the day, but if it is operated in convergence with ESS, which stores electrical energy, it can restrain the fossil energy used in buildings throughout the day. A solution is to converge with PV system and ESS. However, PV systems and ESS connected to the power grid in parallel can cause problems of electrical stability. A study was conducted on the case of failure to detect islanding operation under the parallel operation of PV generation and ESS that are connected in parallel to power grid. Experiments conducted various non-islanding detections under the operating conditions. In the experiment results, when one PCS - PV inverter or ESS inverter - was operating under the islanding condition, it stopped working within 0.5 seconds of the Korean grid standard. However, when both of PV inverter and ESS inverter were operating at the same time under the islanding situation, the anti-islanding algorithm did not operate normally and both inverters continuously supplied power to the connected RLC loads. islanding detection Algorithm developed by each inverter manufacturer has caused this phenomenon. Therefore, this paper presented a new test standard for islanding detection.

• Journal of Korean Academy of Oral Health
• /
• v.42 no.4
• /
• pp.199-203
• /
• 2018

Objectives: The market for bottled water is increasing steadily in South Korea. Bottled water contains several naturally occuring minerals, such as calcium, magnesium, sodium, and fluoride. Fluoride is proven to be effective in preventing dental caries. In South Korea, the maximum permissible concentration of fluoride is 2 ppm for bottled water and 1.5 ppm for tap water. The aim of this study was to investigate the fluoride content of different commercially available brands of bottled water in South Korea, and compare the measured fluoride concentration to the concentration written on the label of each brand of bottled water. Methods: Twenty-seven of the 59 different brands of bottled water produced in South Korea were investigated in this study. Three bottles of each brand were purchased from supermarkets, marts, and convenience stores in each region of Korea in August 2016. For each bottled water brand, the fluoride content was measured three times using a fluoride-ion selective electrode (Orion ionplus Fluoride Electrode 9609, Orion Research, USA). The calibration curve was generated using 0.2 and 2 ppm standard solutions, and confirmed using a 1 ppm standard solution. Results: The mean fluoride content of the 27 brands of bottled water was $0.374{\pm}0.332mg/L$ (range=0.040 to 1.172 mg/L). The fluoride content was labeled by the manufacturer, on each of the tested brands of bottled water. In eight brands, the labeled fluoride content differed from the experimental data. The minimum to maximum fluoride content measured from 10 brands showed a variation of 0.3 mg/L or more when compared to the labeled fluoride content. Conclusions: This study investigated the fluoride content of various brands of bottled water produced in South Korea and compared the measured fluoride levels with fluoride information on the bottle labels. To ensure that consumers are suitably informed regarding their exposure to fluoride, correct labelling of fluoride content in bottled water is important.

• Journal of the Korean Society of Radiology
• /
• v.12 no.7
• /
• pp.833-844
• /
• 2018

Dual energy X-ray absorptiometry is mainly used as an X-ray test method. For equipment manufactured GE and Hologic, cross-calibration analyses (CCA) of machines from the same manufacturer and between units from different manufacturers have been conducted, but the CCA of equipment manufactured in Korea are inadequate. Through CCA, we present a formula of the intersections between the Korean medical equipment company (KEC) with GE and Hologic manufactured DXA, and among the KEC DXA. The CCA was conducted for the European Spine Phantom on DXA from four KEC and three global medical equipment company (GEC) manufacturers. We compared bone mineral density (BMD) values and calculated the CCA equation by linear regression analysis. The standard-deviations (SD) of the BMD values were highest for the Dexxum T for the low, medium, and high spine, which were 0.030, 0.029, and 0.037, respectively. The smallest SD in the low and medium vertebrae were 0.005 and 0.004 for the Horizon Ci, respectively, and 0.005 for the Osteo Pro Max in the high vertebrae. Based on the intersection equations of the KEC DXA established in this study, CCA of various KEC DXA should be established for more accurate follow-up of BMD tests in clinical environments.

• Korean Journal of Heritage: History & Science
• /
• v.45 no.3
• /
• pp.100-113
• /
• 2012

In the midst of recent active excavation, lots of Silla(新羅) roof-end tiles are unearthed in Yeongnam area(嶺南地域). These are confirmed the same tile frame as the Silla tiles excavated in Gyeongju(慶州). It is represented by the Silla tiles excavated in Ingaksa Temple(麟角寺) excavation research. Roof-end tile with arabesque design(唐草文平瓦當) etc. including roof-end tile with lotus design(蓮花文圓瓦當) are judged to be the tile frame produced by the same frame of roof-end tile that was excavated in Gyeongju, Wolseong(月城) and Hwangyongsa Temple(皇龍寺址). There are three kinds of cases concerning the transportation of tile manufacture ; the roof-end tile manufactured in Gyeongju directly moved to each region, only tile frame moved to site to be manufactured there, and tile manufacturer moved to site to manufacture there. This article considers the case of the roof-end tile manufactured in Gyeongju that was directly moved to each region. In case of the Silla tiles excavated in region especially Ingaksa Temple, the aspects of tiles in accordance with different era show the repeated coexistence, expansion and maintenance. This situation is significant as a clue to understand the supply from Gyeongju not as temporary, but as continuous. On the other hand, if the Gyeongju tiles flowed directly into each region, and if the road was built of gravels and the means of transportation was cart, the damage from movement must never be prevented. On the contrary, transportation through waterway might be advantageous due to the reduction of labor and damage rate and the easiness of loading. Accordingly, it tells us why the ruins where roof-end tiles were excavated located near big and small rivers or streams. Of course there are some ruins located in a fixed distance, but the distance may be enough to endure the impact put on tiles from the overland movement. Therefore, in case of direct inflow form long distance, transportation must be finished by overland movement after waterway movement.