• Journal of Radiation Protection and Research
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• v.38 no.1
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• pp.22-28
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• 2013

The skyshine effect is an essential and important phenomenon in the shielding design of the high energy accelerator. In this study, a new estimation method of neutron skyshine was proposed and was verified by comparison with existing methods. The effective dose of secondary neutrons and photons at the locations that was far away from high-energy electron accelerator was calculated using FLUKA and PHITS Monte Carlo code. The transport paths of secondary radiations to reach a long distance were classified as skyshine, direct, groundshine and multiple-shine. The contribution of each classified component to the total effective dose was evaluated. The neutrons produced from the thick copper target irradiated by 10 GeV electron beam was applied as a source term of this transport. In order to evaluate a groundshine effect, the composition of soil on the PAL-XFEL site was considered. At a relatively short distance less than 50 m from the accelerator tunnel, the direct and groundshine components mostly contributed to the total effective dose. The skyshine component was important at a long distance. The evaluated dose of neutron skyshine agreed better with the results using Rindi's formula, which was based on the experimental results at high energy electron accelerator. That also agreed with the estimated dose using the simple evaluation code, SHINE3, within about 20%. The total effective dose, including all components, was 10 times larger than the estimated doses using other methods for this comparison. The influence of multiple-shine path in this evaluation of the estimation method was investigated to be bigger than one of pure skyshine path.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2006.09a
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• pp.45-60
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• 2006

최근 국제적으로 생물자원의 중요성이 재인식됨에 따라 이들에 대한 체계적이고 안정적인 정보의 구축 및 활용이 국가경쟁력의 척도로 간주할 정도로 중요성이 커지고 있는 실정이다. 또한, 우리나라는 국토의 64%가 산림으로 되어 있어서 다양한 생물종이 서식하는데 매우 적합한 조건을 갖추고 있다. 이에 따라 산림청과 국립수목원은 국가식물자원정보시스템에 이어 곤충정보에 대한 정보화 사업을 2001년부터 추진해오고 있으며 이 결과로 현재 33만여 점에 곤충표본정보가 구축되기에 이르렀다. 현재까지 국내 유수 곤충표본보유기관 22개 기관이 본 사업에 참여하여 다양하고 내실 있는 정보구축이 이루어져 왔으며 이를 통해 명실 공히 국가적인 곤충자원정보망을 갖추게 되었다. 곤충DB의 국가적인 사업이 추진된 지 6년차에 이르는 2006년도에는 정보통신부의 지원을 받아 14개 표본보유기관이 참여하여 곤충표본DB구축을 중점 추진할 계획이다. 2006년도의 목표량은 곤충표본정보 17,000점으로 기존구축자료 이외에 추가가 필요한 표본정보위주로 구축될 예정이다. 또한, 이미 구축된 곤충표본자원의 활용도와 가치를 높이기 위해서는 더욱 다양하고 많은 자료의 표본을 추가하여 DB화를 추진함은 물론 이들 각각의 정보들을 식물정보와 연계하여 분석 가능토록 하고 GIS시스템을 도입하여 명실공히 국가적인 곤충자원정보의 종합관리가 될 수 있도록 추진하고 있다. 본 사업이 충실히 수행될 경우 국가 주요 생물자원 중 하나인 곤충정보의 DB확대 구축을 통한 전체적인 현황파악 및 체계적인 관리가 가능해 질 것이며, 이와 관련하여 정보화적인 측면, 경제적 측면, 사화 문화적 측면에서 다양한 효과가 기대되며 앞으로도 이에 대한 내실 있는 운영을 위해서는 정부차원의 종합적인 지원 및 관리가 요구되는 시점으로 판단된다.pm3.42$, 저층수 $23.43\pm3.38$이었으며, 전반적으로 해역별 수질기준 I등급 내지는 II등급을 유지하고 있었고, 공간적으로는 외해측으로 갈수록 외해수와 혼합 확산되어 양호한 수질을 나타내었다. 장기적인 변동특성은 세그룹으로 구분되어진다.기 실험결과 용출용매로 증류수와 해수를 이용했을 때, 제강 슬래그에서 용출되는 납, 구리, 카드뮴, 수은의 용출 경향의 차이를 확인할 수 있었고 이에 따라서, 납, 구리, 카드뮴의 용출 유해성은 낮기 때문에 해양구조물로의 제강슬래그 유효이용은 적합할 것으로 판단되었다.im80%$로 계산되었다. 열형광선량계로 측정된 방사선량은 각각 1.8, 1.2, 0.8, 1.2, 0.8 (70 cm 거리) cGy로 측정되었으며, 환자의 복부 표면에서의 서베이메터를 이용한 측정량은 10.9 mR/h였다. 차폐구조물의 사용 시 전체 치료 동안에 태아선량은 약 1 cGy 정도로 평가되었다. 결론 : AAPM Report No.50의 자료에 따르면, 임산부의 방사선 치료 시 태아의 방사선 피폭선량은 5 cGy 이하일 경우에 방사선 피폭에 따른 태아의 위험이 거의 없는 것으로 제시되고 있다. 본원에서 차폐 구조물을 설치하였을 경우에 측정된 태아선량은 약 1 cGy로 측정되었고, 고안된 차폐구조물은 태아에 도달하는 방사선량을 감소시키기에 적합한 설계임이 입증되었다. 아니라 일반종합병원에서도 CTX-M형 ESBL 생성 E. coli와 K. pneumoniae가 존재하며 확산 중임을 시사한다. 앞으로 CTX-M형 ESBL의 만연과 변종 CTX-M형 ESBL의 출연을 감시하기 위한 정기적인 연구와 조사가 필요한 것으로 생각한다., A2-1, B1-1, B2-1의 경우, 강우 일수 감소 이전과 연 유출량 변화는 거의

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.884-891
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• 2016

A secondary injection system in a diesel engine has benefits: it can be controlled independently without interrupting engine control, it can be adapted to various layouts for exhaust systems, and it pose no reductant dilution problems compared to post injection systems in the combustion chamber or other supplemental reductant injections. In a secondary injection system, the efficiency of the catalyst depends on the method of reducing the supply. The reductant needs to be maintained and optimized with constant pressure, the positions and angles of injector is a very important factor. The concentration and amount of reductant can be changed by adjusting secondary injection conditions. However, secondary injection is highly dependent upon the type of injector, injection pressure, atomization, spray technology, etc. Therefore, it is necessary to establish injection conditions the spray characteristics must be well-understood, such as spray penetration, sauter mean diameter, spray angle, injection quantity, etc. Uniform distribution of the reductant corresponding to the maximum NOx reduction in the DeNOx catalyst system must also assured. With this goal in mind, the spray characteristics and impingement plate types of a secondary injector were analyzed using visualization and digital image processing techniques.

• Journal of the Korean Geophysical Society
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• v.10 no.1
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• pp.1-12
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• 2007

A method to quickly estimate broadband moment magnitudes (Mwp) to warn regional and teleseismic tsunamigenic earthquakes is tested for application of the method to the different seismic observation environment. In this study, the Mwp is calculated by integrating far-field P-wave or pP-wave of vertical component of displacement seismograms in time domain from earthquakes, having magnitude greater than 5.0 and occurred in and around the Korean peninsula from 2000 to 2006. We carefully set up the size of the time window for the computations to exclude S wave phases and other phases following after the P wave phase. The P wave velocities and the densities from the averaged Korean crustal model are used in the computations. Instrumental correction was performed to remove dependency on the seismograph. The Mwp after the instrumental correction is about 0.1 greater than the Mwp before the correction. The comparison of our results to the those of foreign agencies such as JMA and Havard CMT catalogues shows a higher degree of similarity. Thus our results provide an effective tool to estimate the earthquake size, as well as to issue the necessary information to a tsunami warning system when the effective earthquake occurs around the peninsula.

• Journal of Internet of Things and Convergence
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• v.6 no.2
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• pp.65-72
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• 2020

The study aims to measure and analysis the spatial equity of Medical welfare facilities for older persons and services, and, based on this, to seek the plan to secure the fairness. To this end, the research was carried out by converging the studies of geography and regional development for the equity of social welfare studies and space arrangement on types and functions of Medical welfare facilities for older persons. The main results of the study showed that, first, in case of the spatial arrangement(desire-to-service), Medical welfare facilities for older persons are located in all areas of cities(Si) and counties(Gun) but mostly existing in cities. Second, in case of the equity of regional distribution of Medical welfare facilities for older persons, it can say the equity in Gun is higher than Si, comparing the regions of Si and Gun. Third, in case of spatial equity of sanatorium for older persons, the spatial equity of care facilities for older persons showed statistical difference depending on the time required to reach the facility, but no difference on distance. This study made various suggestions based on the results of the above research, and suggested the necessity of convergence studies grafting technologies such as AI and the Internet of Things.

• Journal of Korea Water Resources Association
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• v.48 no.2
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• pp.115-126
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• 2015

In recent years, debris flow disaster has occurred in multiple locations between high and low mountainous areas simultaneously with a flooding disaster in urban areas caused by heavy and torrential rainfall due to the changing global climate and environment. As a result, these disasters frequently lead to large-scale destruction of infrastructures or individual properties and cause psychological harm or human death. In order to mitigate these disasters more effectively, it is necessary to investigate what causes the damage with an integrated model of both disasters at once. The objectives of this study are to analyze the mechanism of debris flow for real basin, to determine the PMP and run-off discharge due to the DAD analysis, and to estimate the influence range of debris flow for fan area according to the scenario. To analyse the characteristics of debris flow at the real basin, the parameters such as the deposition pattern, deposit thickness, approaching velocity, occurrence of sediment volume and travel length are estimated from DAD analysis. As a results, the peak time precipitation is estimated by 135 mm/hr as torrential rainfall and maximum total amount of rainfall is estimated by 544 mm as typhoon related rainfall.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.151-151
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• 2013

무기물 기반, Si-based 태양전지에 비해 가볍고 저렴하다는 관점에서 유기태양전지에 대한 연구가 진행되고 있다. 유기태양전지는 Si-based 태양전지에 비해 그 효율이 낮다는 점이 문제로 제기되어 왔지만, 억셉터와 도너의 nanocomposite 구조인 bulk-heterojunction (BHJ) 구조가 개발이 되면서 유기물의 짧은 엑시톤(exciton) 거리를 극복할 수 있게 되어 그 효율이 비약적으로 증가되는 결과를 낳았다. 또한 넓은 범위의 파장을 흡수 할 수 있는 작은 band-gap을 갖는 물질이 개발됨으로써 유기 태양전지의 효율은 점차 증가하고 있다. 최근에는 독일 회사인 Heliatek에서 12%가 넘는 유기태양전지를 발표함으로써 유기태양전지가 Si-based 태양전지를 대체할 수 있는 차세대 에너지 공급원으로의 가능성을 충분히 보였다. 이런 유기 태양전지는 하부 투명전극인 인듐주석산화물(ITO)/정공이동층(PEDOT:PSS)/광흡수층/전자이동층(LiF)/낮은 일함수를 갖는 상부전극인 Al 구조의 일반적인 구조; ITO/전자이동층/광흡수층/정공이동층/높은 일함수를 갖는 상부전극(Ag), 전하의 이동방향이 반대인 역구조 태양전지, 두 가지로 분류할 수 있다. 하지만 소자 안정성의 관점에서 일반적인 구조의 태양전지는 ITO/PEDOT:PSS 계면에서의 화학적 불안정성과, 낮을 일함수를 갖는 상부전극이 쉽게 산화되는 등의 문제가 있어 상부전극으로 높은 일함수를 갖는 전극을 사용하는 역구조 태양전지가 더 유리하다. 이러한 역구조 태양전지에서 효율을 높일 수 있는 요인 중 하나는 전자이동층에 있다. 광흡수층에서 형성되어 분리된 전자가 전극으로 이동하기위해서는 전자이동층을 거쳐야 한다. 하지만 이 전자이동층 내에서의 전자 이동속도가 느리다면, 즉 저항이 크다면 광흡수증과의 계면에서 Back electron trasnfer현상으로 재결합이 일어나게 되어 전극으로 도달하는 전자의 양이 줄어들게 되고, 이는 유기태양전지 효율을 낮추는 요인이 된다. 전자이동층 자체의 저항뿐만 아니라, 전자이동층의 표면 거칠기(morphology) 또한 유기 태양전지의 효율을 좌우하는 요인 중 하나이다. 광흡수층과 전자이동층의 계면에서 전자의 이동이 일어나는데, 전자이동층의 표면 거칠기가 크게되면 그 위에 박막으로 형성되는 광흡수층과의 계면저항이 증가하게 되고, 이는 광흡수층에서 전자이동층으로의 원활한 전자이동을 저해함으로써 소자 효율의 감소를 일으키게 된다. 따라서 우리는 전자이동층인 ZnO 박막의 스퍼터링 조건을 변화시킴으로써 ZnO 층의 두께에 따른 광투과도, 전기전도성 변화 및 유기태양전지의 효율변화와, 표면 거칠기에 따른 광변환 효율 변화를 관찰하고자 한다.

• Fire Science and Engineering
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• v.31 no.5
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• pp.63-69
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• 2017

This study describes the development of a long-distance hose for ultra-high pressure operation, which can be used in conjunction with an ultra-high pressure pump and can be effectively applied to the fire suppression of high-rise buildings and a long, large tunnels. Also, it has phosphorescent properties, which can help to secure the withdrawal route of the fire-fighters when they are threatened by the fire. We developed an ultra-high pressure hose aiming at a pressure of 3 MPa and a flow rate of 2000 lpm and developed an ultra-high pressure fire hose that can withstand this very high pressure by using a double jacket, triple polyurethane coating and warf (Wp) of 52. In order to ensure the performance of the developed ultra-high pressure hose, its structure, appearance, leakage at high pressure, length and elongation were inspected by a certified certification agency, who also subjected it to a peeling test, friction test, breaking pressure test and free fall test. Also, it was studied in addition to the luminescent high-pressure hose for fire-fighting. In the phosphorescence test, the luminance measurement value was more than the reference value of the luminance test after 40 minutes, which confirmed that its performance was satisfactory for fire-fighting products. In the future, if such an ultra-high pressure fire hose were commercialized and applied in the field, it could contribute to securing improved fire suppression and safer exit from fires, as compared to the fire hoses currently used in the suppression of fires in skyscraper buildings and long tunnels.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.638-644
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• 2018

Relay systems have recently gained attentions because of its capability of cell coverage extension and the power gain as the one of key technologies for 5G. Relays can be exploited for small-cell base stations and the autonomous network, where communication devices communicate with each other cooperatively. Therefore, the relay technology is expected to enable the low power and large capacity communication. In order to maximize the benefits of using a limited number of relays, the efficient relay selection method is required. Especially, when two nodes exchange their data with each other via relay, the relay selection can maximize the average data rate by the spatial location of the relay. For this purpose, the average data rate is analyzed first according to the relay selection. In this paper, we analyzed the average data rate when two nodes exchange their data via dual-hop decode and forward relaying considering the interference by the concurrent transmission under Nakagami-m fading channel. The correctness of the analysis is verified by the Monte Carlo simulation. The results show that the concurrent transmission is superior to the non-concurrent transmission in the high required data rate region rather than in the low required data rate region.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.143-149
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• 2019

In this study, a U-shape composite beam was developed to be effectively used for a steel parking lot which is 8m or lower in height. When the U-shape composite beam was applied to a steel parking lot, essential considerations were story-height and long-span. In addition, due to the mixed structural system with reinforced concrete and steel material, the U-shape composite beam needed to have a structural integrity and reliable performance over demand capacity. The main objective of this study was to investigate the performance of the structure consisting of the reinforced concrete (RC) slab and U-shape beam. A U-shape composite beam generally used at a parking lot served as a control specimen. Four specimens were tested under four-point bending. To calculate theoretical values, strain gauges were attached to rebar, steel plate, and concrete surface in the middle of the specimens. As the results, initial yielding strength of the control specimen occurred at the bottom of the U-shaped steel. After yielding, the specimen reached the maximum strength and the RC slab concrete was finally failed by concrete crush due to compressive stress. The structural performance such as flexural strength and ductility of the specimen with the increased beam depth was significantly improved in comparison with the control specimen. Furthermore, the design of the U-shape composite beam with the consideration of flexural strength and ductility was effective since the structural performance by a negative loading was relatively decreased but the ductile behavior was evidently improved.