• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1266-1276
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• 2018

In this paper, three-dimensional neutronic calculations were performed in order to calculate the dependency of CRW on the temperature of fuel and moderator and the moderator void. Calculations were performed using the known MTR_PC computer codes in the core configuration 61 of TRR. The dependency of CRW on the fuel temperature in the range of $20-340^{\circ}C$ and the moderator temperature of each control rods were studied. Based on the positions of the control rods, the calculations were performed in three different cases, named case A, B and C. By the results, the worth of each control rods increases by increasing of the coolant temperature in all methods, however, the total CRW is somewhat independent of the fuel temperature. In addition, the results showed that the variation of CRW versus density depends on the positions of the control rods and the most change in CRW in the coolant temperature, $20-100^{\circ}C$ (279 pcm), belongs to SR4. Finally the effect of void on CRW was studied for different void fraction in coolant. The most worth change is about $2 for 40% void fraction related to SR1 and SR3 in case B. For 40% void fraction, the total CRW increases about $7.5, $6 and $7 in cases, A, B and C, respectively.

• Journal of Advanced Marine Engineering and Technology
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• 제38권2호
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• pp.123-132
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• 2014

The maritime sector is advancing with dedicated endeavor to reduce greenhouse gas in addressing issues with regards to global warming. Since 01 January 2013, the International Maritime Organization (IMO) regulation mandatory requirement for Energy Efficiency Design Index (EEDI) has been in place and should be satisfied by newly-built ships of more than 400 gross tonnage and the Ship Energy Efficiency Management Plan (SEEMP) for all ships type. Therefore, compliance to this necessitates planning during the design stage whereas verification can be carried-out through an acceptable method during sea trial. The MEPC-approved 2013 guidance, ISO 15016 and ISO 19019 on EEDI serves the purpose for calculation and verification of attained EEDI value. Individual ships EEDI value should be lower than the required value set by these regulations. The key factors for EEDI verification are power and speed assessment and their synchronization. The shaft power can be measured by telemeter system using strain gage during sea trial. However, calibration of shaft power onboard condition is complicated. Hence, it relies only on proficient technology that operates within the permitted ISO allowance. On the other hand, the ship speed can be measured and calibrated by differential ground positioning system (DGPS). An actual test on a newly-built vessel was carried out to assess the correlation of power and speed. The Energy-efficiency Design Index or Operational Indicator Monitoring System (EDiMS) software developed by the Dynamics Laboratory-Mokpo Maritime University (DL-MMU) and Green Marine Equipment RIS Center (GMERC) of Mokpo Maritime University was utilized for this investigation. In addition, the software can continuously monitor air emission and is a useful tool for inventory and ship energy management plan. This paper introduces the synchronization and identification method between shaft power and ship speed for EEDI verification in accordance with the ISO guidance.

• Journal of Radiation Protection and Research
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• 제46권2호
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• pp.66-79
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• 2021

Background: The Japan Atomic Energy Agency (JAEA) is specified in the Disaster Counter-measures Basic Act as a designated public corporation for dealing with nuclear disasters. Materials and Methods: The Nuclear Emergency Assistance and Training Center (NEAT) was established in 2002 as the activity base providing technical assistance to both national and local governments during nuclear emergencies. The NEAT has a robust structure and utilities and special installations, and it organizes training and exercises. Results and Discussion: Due to an offshore earthquake that caused a devastating tsunami in March 2011, a nuclear accident occurred at the Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Station. The NEAT responded by conducting off-site environmental radiation monitoring and contamination screening, dispatching special vehicles, offering telephone consultations, and calculating the dispersion of radioactive materials. An examination of the emergency response activities revealed that the organization was prepared for these types of disasters and was able to plan long-term response. Conclusion: As a designated public corporation, the JAEA technically supports the national government, the Fukushima prefectural government, and the Ibaraki prefectural government, all of which responded to the off-site emergencies resulting from the March 2011 Fukushima Daiichi accident

• Journal of Radiation Protection and Research
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• 제44권2호
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• pp.72-78
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• 2019

Background: In the calibration and testing laboratory of Korea Atomic Energy Research Institute, the old X-ray generator used for the production of reference X-ray fields was replaced with a new one. For this newly installed X-ray irradiation system, beam alignment as well as the verification of beam qualities was conducted. Materials and Methods: The existing X-ray generator, Phillips MG325, was replaced with YXLON Y.TU 320-D03 in order to generate reference X-ray fields. Theoretical calculations and Monte Carlo simulations were used to determine initial filter thickness. Beam alignment was performed in three steps to deliver a homogeneous radiation dosage to the target at different distances. Finally, the half-value layers were measured for different X-ray fields to verify beam qualities by using an ion chamber. Results and Discussion: Beam alignment was performed in three steps, and collimators and other components were arranged to maintain the uniformity of the mean air kerma rate within ${\pm}2.5%$ at the effective beam diameter of 28 cm. The beam quality was verified by using half-value layer measurement methods specified by American National Standard Institute (ANSI) N13.11-2009 and International Organization for Standardization (ISO)-4037. For each of the nine beams than can be generated by the new X-ray irradiation system, air kerma rates for X-ray fields of different beam qualifies were measured. The results showed that each air kerma rate and homogeneity coefficient of the first and second half-value layers were within ${\pm}5%$ of the recommended values in the standard documents. Conclusion: The results showed that the new X-ray irradiation system provides beam qualities that are as high as moderate beam qualities offered by National Institute of Standards and Technology in ANSI N13.11-2009 and those for narrow-spectrum series of ISO-4037.

• 건축역사연구
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• 제18권2호
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• pp.47-63
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• 2009

This study focused on changes in form and spatial uses of Urban Hanok in Bukchon, Seoul. There are 10 representative cases which have been renovated through the policy of 'Preservation & Regeneration of Bukchon' by Seoul metropolitan government and other experts. Changes in form and spatial uses of Urban Hanok in Buckon are as follows. First, Changes of scale. Trough removing extension parts, facade of renovated Hanoks are 'transformed' into recovering their identity. Using basements or lofts, intensive application of spaces is transformation which promotes the vitality of Hanoks. Second, changes of space organization. As Hanok changes its function from residence to commercial or cultural use, il a1so changes space character or reorganizes space organization. It is important that deciding function of Hanok has to adjust its scale and organization. Third, changes of construction performance. Through introducing new material and constructing method, performance of wall has been changed respecting its wooden structure and interior-exterior figure. However, technical studies must back it up not to destroy its value of eco-friendly architecture. Fourth, changes of facility systems, like floor heating system. They changes floor level of Hanok equally, and then sections of Hanok have became simple. Furthermore, inserting new facility space, such as boiler room, stand-up kitchen, bathroom and toilet, organization of space also changed. It is necessary that wise alternative proposal through the method of transformation or mutation must be presented. These four changes can be classification into method of 'transformation' and 'mutation'. Changes of scale are method of transformation and changes of space organization are method of mutation. Also, while changes of construction performance are mutation, changes of facility systems are transformation. Recently, as price of lots have been increased, a lot of Hanoks have been commercialized. Thc commercial energy threat 'the identity of Bukchon as residential area'. From now on, to operate 'identity' and 'vitality' complementary, it is necessary to make up for the preservation policy of Hanok and consolidate renovating standards of Hanok which correspond to character of particular region and building usage.

• 한국안전학회지
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• 제33권4호
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• pp.119-126
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• 2018

In recent years, as flood damage caused by heavy rains increased, the great-depth tunnel using urban underground space is emerging as a countermeasure of urban inundation. The great-depth tunnel is used to reduce urban inundation by using the underground space. The drainage efficiency of great-depth tunnel depends on the intake design, which leads to increase discharge into the underground space. The spiral intake and the tangential intake are commonly used for the inlet facility. The spiral intake creates a vortex flow along the drop shaft and reduces an energy of the flow by the wall friction. In the tangential intake, flow simply falls down into the drop shaft, and the design is simple to construct compared to the spiral intake. In the case of the spiral intake, the water level at the drop shaft entrance is risen due to the chocking induced by the flowrate increase. The drainage efficiency of the tangential intake decreases because the flow is not sufficiently accelerated under low flow conditions. Therefore, to compensate disadvantages of the previously suggested intake design, the multi-stage intake was developed which can stably withdraw water even under a low flow rate below the design flow rate. The hydraulic characteristics in the multi-stage intake were analyzed by changing the flow rate to compare the drainage performance according to the intake design. From the measurements, the drainage efficiency was improved in both the low and high flow rate conditions when the multi-stage inlet was employed.

• Nutrition Research and Practice
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• 제10권1호
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• pp.108-114
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• 2016

BACKGROUND/OBJECTIVES: Sustainable practices in foodservice organizations including commercial and noncommercial ones are critical to ensure the protection of the environment for the future. With the rapid growth of the foodservice industry, wiser usage of input sources such as food, utilities, and single use packaging should be reconsidered for future generations. Therefore, this study aims to investigate the customer's perceptions on sustainable practices and to identify the relationship among sustainable practices, social contribution and purchase intention. SUBJECTS/METHODS: The study was conducted using content analyses by reviewing articles on sustainable food service practices published domestically and abroad. Thereafter, data were collected with a face-to-face survey using a questionnaire and analyzed with factor analyses and multiple regressions. RESULTS: Sustainable practices classified with factor analysis consisted of 6 dimensions of green food material procurement, sustainable food preparation, green packaging, preservation of energy, waste management, and public relations on green activity, with a total of 25 green activities in foodservice operations. Consumers were not very familiar with the green activities implemented in the foodservice unit, with the lowest awareness of "green food material procurement (2.46 out of 5 points)", and the highest awareness of "green packaging (3.74)" and "waste management (3.28). The factors influencing the perception of social contribution by foodservice organizations among 6 sustainable practice dimensions were found to be public relations on green activity (${\beta}=0.154$), waste management (${\beta}=0.204$) and sustainable food preparation (${\beta}=0.183$). Green packaging (${\beta}=0.107$) and the social contribution of the foodservice organization (${\beta}=0.761$) had strong relationships with the image of the organization. The purchase intentions of customers was affected only by the foodservice image (${\beta}=0.775$). CONCLUSIONS: The results of this study suggest that sustainable practices by foodservice organization present a good image to customers and increase the awareness of valuable contributions that benefit the customer as well as the community.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2021년도 추계학술대회
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• pp.201-202
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• 2021

국제해운에서의 선박으로부터 배출되는 온실가스에 대한 규제는 가일층 강화되고 있으며 국제해사기구에서 수립한 온실가스 저감목표는 기술적 및 운항적 측면에서 해운선사에는 커다란 도전으로 작용하고 있다. 국제해사기구는 탄소집약도 기준 2008년 대비하여 2030년 까지 30% 및 2050년 까지 70%를 감축하고 총배출량 기준 50%까지 감축하는 것을 목표로 삼고 있다. 이의 실현을 위해 IMO는 단기 및 중장기 조치를 일부 채택하여 2023년부터 현존선에 대한 에너지효율 지표인 EEXI 적용과 일부 선형에 대한 EEDI 3단계 조기 적용 등의 기술적 조치 채택하였으며 선박의 탄소집약지수인 CII를 채택하여 운영적 측면도 온실가스 저감을 위한 조치를

• Advances in nano research
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• 제3권3호
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• pp.143-168
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• 2015

Initiation of crack and its growth simulation requires accurate model of traction - separation law. Accurate modeling of traction-separation law remains always a great challenge. Atomistic simulations based prediction has great potential in arriving at accurate traction-separation law. The present paper is aimed at establishing a method to address the above problem. A method for traction-separation law prediction via utilizing atomistic simulations data has been proposed. In this direction, firstly, a simpler approach of common neighbor analysis (CNA) for the prediction of crack growth has been proposed and results have been compared with previously used approach of threshold potential energy. Next, a scheme for prediction of crack speed has been demonstrated based on the stable crack growth criteria. Also, an algorithm has been proposed that utilizes a variable relaxation time period for the computation of crack growth, accurate stress behavior, and traction-separation atomistic law. An understanding has been established for the generation of smoother traction-separation law (including the effect of free surface) from a huge amount of raw atomistic data. A new curve fit has also been proposed for predicting traction-separation data generated from the molecular dynamics simulations. The proposed traction-separation law has also been compared with the polynomial and exponential model used earlier for the prediction of traction-separation law for the bulk materials.

• 디지털산업정보학회논문지
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• 제9권2호
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• pp.89-97
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• 2013

The green IT technology is being introduced in diverse sectors, especially in the data center and green computer sectors. Rack-type PCs, which have been developed by improving the computer hardware, are effective for data centers and large businesses, but they are not usually introduced in small organizations such as small and medium businesses and schools because they require high initial costs. Power-saving PC software enables the inexpensive power control, but the installation of the power-saving software in all computers in the organization is not an easy task. Computer users in the organization are usually not cooperative as they do not think the power-saving cost is directly related to themselves. In this paper, a technique wherein the server has a restriction in providing the IP address to the computers that has no power-saving software is proposed, so that users will cooperate in the PC power-saving system to avoid inconvenience. In order to provide restricted IP address periodically, the server makes a request of power-saving software installation check for user's PC. Proposed technique is more effective ways to save computer energy, because it does not depend on specific systems or organizations.