• 한국전자파학회논문지
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• 제8권4호
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• pp.403-414
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• 1997

각종 원인에 기인하는 궤도별 우주폐기물의 분포는 우주환경에 있어서 위성통신 방송 및 통신신호의 전파전파 에 방해요소로 작용하게 된다. 본 논문에서는 수치해석적 접근에 의해 우주폐기물의 공간분포밀도와 사용 주파 수의 변화에 따른 EM파의 정규화 산란계수를 계산하고 우주폐기물에 의한 감쇠도 및 위상변화를 구하였다. 그 결과 우주폐기물에 의한 위성통신 방송선호 전파에 었어서 감쇠도는 베셀함수에 의해 표현된 전계 요소의 진폭 함수의 실수부에 의해 가장 큰 영향을 받게 되고 위상 변화량은 허수부에 의해 주로 결정됨을 분석하였다. 본 논 문의 결과는 우주폐기물의 기하급수적 증가에 따른 우주환경의 새로운 인식과 우주폐기물을 고려한 위성통신망 의 링크버짓 설계의 활용에 적합하다.

• Journal of Radiation Protection and Research
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• 제43권1호
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• pp.20-28
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• 2018

Background: Heat energy produced in nuclear reactors and nuclear fuel cycle facilities interactions modifies the physical properties of the shielding materials containing water content. Therefore, in the present paper, effect of the heat on shielding effectiveness of the concretes is investigated for gamma and neutron. The mass attenuation coefficients, effective atomic numbers, fast neutron removal cross-section and exposure buildup factors. Materials and Methods: The mass attenuation coefficients, effective atomic numbers, fast neutron removal cross-section and exposure buildup factors of ordinary and heavy concretes were investigated using NIST data of XCOM program and Geometric Progression method. Results and Discussion: The improvement in shielding effectiveness for photon and reduction in fast neutron for ordinary concrete was observed. The change in the neutron shielding effectiveness was insignificant. Conclusion: The present investigation on interaction of gamma and neutron radiation would be very useful for assessment of shielding efficiency of the concrete used in high temperature applications such as reactors.

• 한국문헌정보학회지
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• 제37권2호
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• pp.135-152
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• 2003

인터넷의 급속한 확산으로 디지털콘텐츠가 기하급수적으로 증가하고, 그 종류도 매우 다양해졌다. 분산 네트워크 환경하인 인터넷을 통해 디지털콘텐츠의 식별 및 검색을 용이하게 하기 위해서는 메타데이터의 조직과 관리가 필요하다. 본 연구는 여러 분야에서 다양하게 접근되고 있는 메타데이터 포맷의 데이터 요소를 비교 분석함으로써 상이한 메타데이터 포맷의 상호운용성 확보를 위한 기초 자료를 제공하고자 하였다. 포괄적으로 모든 영역에서 사용되고 있는 디지털콘텐츠의 메타데이터 포맷으로 Dublin Core, Semantic Header, MARC, IAFA Templates TEI Header를 선정하여 문헌고찰을 통하여 비교분석을 수행하였다.

• 스마트미디어저널
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• 제8권2호
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• pp.80-85
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• 2019

일반적으로 층간소음은 자유음장의 관점에서 데시벨(A)로 측정하고 있다. 논문에서 우리는 확산음장의 관점에서 층간진동가속도의 측정방법을 제안한다. 제안된 방법은 공동주택의 고유진동을 가속도로 측정하여 그 평균값 $20mm/s^2$를 기수의 등비수열로 나타내면, 진도계감도와 유사하게 진동체화식으로 표상할 수 있다. 이 이론을 토대로 본고는 진원지의 층간진동가속도를 HCI시스템에서 최적의 사용자 경험(UX)할 수 있도록 수식을 제시하였다.

• Structural Engineering and Mechanics
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• 제70권4호
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• pp.431-443
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• 2019

The present paper illustrates a numerical investigation on the failure behaviour of ring-stiffened cylinder subjected to external hydrostatic pressure. The published test data of steel welded ring-stiffened cylinder are surveyed and collected. Eight test models are chosen for the verification of the modelling and FE analyses procedures. The imperfection as the consequences of the fabrication processes, such as initial geometric deformation and residual stresses due to welding and cold forming, which reduced the ultimate strength, are simulated. The results show that the collapse pressure and failure mode predicted by the nonlinear FE analyses agree acceptably with the experimental results. In addition, the failure mode parameter obtained from the characteristic pressure such as interframe buckling pressure known as local buckling pressure, overall buckling pressure, and yield pressure are also examined through the collected data and shows a good correlation. A parametric study is then conducted to confirm the failure progression as the basic parameters such as the shell radius, thickness, overall length of the compartment, and stiffener spacing are varied.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4426-4430
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• 2023

In this article, Exposure Buildup Factor(EBF) and the Energy Absorption Buildup Factor(EABF) have been determined for blood, brain, and muscle using the Monte Carlo method which is represented by MCNP5 codes and compared with geometric progression(G-P) fitting method which is represented by Phy-X/PSD online platform. The novelty of the present work is used an energy source of less than 0.1 MeV to determine buildup factors using MCNP5 and using Phy-X/PSD for some human tissues. thus, the energy range used in this case study was 0.06-3 MeV for penetration depths covered 0.5-3 MFP. Results of MCNP5 and Phy-X/PSD are validated against reference values of water that were reported at ANS-6.4.3. present results of EABFs and EBFs for the previously mentioned human tissues appeared good agreement between MCNP5 in comparison with Phy-X/PSD, whereas, the maximum average relative deviation did not exceed 2.37%. results of our article can be used in different medical applications, such as brachytherapy, radiotherapy, and diagnostics.

• Journal of Nutrition and Health
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• 제36권3호
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• pp.280-286
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• 2003

Conjugated linoleic acid (CLA) consists of several geometric isomers of linoleic acid. CLA is found in foods derived from ruminants and exhibits strong anticarcinogenic effects in a variety of animal models. Matrix metalloproteinases (MMPs) play a key role in cancer progression. Specifically, MMP-2 and -9, which hydrolyze the basal membrane type IV collagen, are involved in the initial breakdown of collagen and basement membrane components during tumor growth and invasion. However, the effects of CLA on cancer cell motility and MMP expression and activity are not currently well known. Therefore, the present study examined whether CLA reduces the activity of MMP and cell motility in SW480 and SW620 cells, the human colon cancer cell lines. Gelatin zymography and Western blot analysis revealed that phorbol 12-myristate 13-acetate (PMA) induced the activity and protein expression of Mr 92,000 MMP-9 in both cell lines. To examine whether CLA inhibits the MMP activity, cells were incubated with 100 ngfmL PMA in the presence of various concentrations of CLA. PMA-induced MMP-9 activity was decreased by 20 $\mu$ M CLA in SW480 cells, and by 10 $\mu$ M and 20 $\mu$ M CLA in SW620 cells. Results from the Hoyden chamber assay showed that cell motility was increased by PMA and that PMA-induced cell motility was significantly decreased by 20 $\mu$ M CLA in SW480 cells. These results indicate that CLA may reduce the motility and MMP activity in human colon cancer cells.

• 정보교육학회논문지
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• 제8권4호
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• pp.501-510
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• 2004

최근 ICT 교육의 활성화에 따라 응용 SW(Software) 교육의 중요성이 더해지고 있다. 그런데 지식의 기하급수적인 팽창과 컴퓨터 기술의 급속한 발전에 따라 끊임없이 새로운 SW가 양산되고 있기 때문에 기존의 SW 학습 패러다임은 여러 가지 문제에 봉착하였다. 본 연구는 이와 같은 문제의식을 가지고 문제 상황에서 학습자 스스로 SW의 적절한 기능을 쉽게 찾아 학습하고, 이를 문제 사태에 적용, 효율적으로 해결할 수 있으며, 파지와 전이를 촉진시킬 수 있는 능력을 SW 적응력이라 정의하고, 이를 배양할 수 있는 SW 교수 학습 방법을 탐색하였다. 이를 위해 SW 사용성과 UI(User Interface)디자인을 위한 원칙등을 살펴보고, SW 적응력, UI 디자인 원칙에 따른 SW 학습 전략을 도출하였다. 또한 시범 실습식 SW 교수 학습 방법의 문제점을 살펴보고 SW 적응력 향상을 위한 탐구적 교수 학습 모형을 제안하였다.

• 한국치위생학회지
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• 제7권3호
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• pp.259-271
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• 2007

AIDS is increasing by geometric progression in the world with more seriousness and HIV/AIDS is still spreading. Thus, the study enforced a self-administered survey with 526 dental hygiennics students to carry out an upright recognition and education on AIDS by grasping knowledge and attitude of dental hygienics students who will work at dental hospitals or clinics after graduating in AIDS. As the result, the study got the following conclusion. 1. 51.1% of the students got knowledge on AIDS and the majority out of them got its knowledge through school(35.2%) or mass media(10.8%). 2. The average score of dental hygienics students' knowledge in AIDS was 87.67: The first-grade students(86.00), the second-grade students(88.88) and the third-grade students(88.37) (p=0.000). 3. They had an accurate recognition about AIDS' causes, its infection ways and interceptive methods of its infection way in knowledge of AIDS(p=0.000). 4. In their attitudes for AIDS, the average score was $57.43{\pm}$: The first-grade students(56.19), the second-grade students(57.70) and the third-grade students(58.70)(p=0.001). 5. In their attitudes for AIDS, the students($4.09{\pm}0.82$ scores) responded that they would prepare for AIDS' infection of their families(p=0.004) while, on the other hand, the students($4.06{\pm}0.82$ scores) responded that they wanted to avoid PWA's dental treatment(p=0.001). Therefore, it is judged that vocational education as a specialized worker as well as AIDS education should be realized since it was appeared that they had not enough thought as a mature professional worker. 6. Dental hygienics students who would work at dental hospitals or clinics after graduating were in the environment infected in all diseases and so most of the students($4.23{\pm}0.74$) responded that AIDS education should be included in curriculum.

• 한국정보통신학회논문지
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• 제7권7호
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• pp.1456-1461
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• 2003

최근 멀티미디어 환경에서 보다 진보된 가상현실의 환경을 요구하고 있다. 가상현실은 광범위한 응용분야를 창출할 수 있으며 여러 분야의 핵심적인 기술요소들이 통합되어야만 가상현실을 구현할 수 있고 기술적인 분야에서 커다란 전환을 가져오므로서 최근에 급속한 주목을 받아오고 있다. 동화상 정보 시스템에서 입체영상을 구축하기 위해서는 도서관내 전경 및 도서들의 2D 좌/우 이미지를 활용하여 가상현실 시스템 구조는 display, tracking, computation의 세 가지 구성 요소로 이루어지며, 또한 사운드 출력, 음성 출력, 음성 인식이 요구되어진다. 이러한 3D 가상현실 시스템을 이용하여 구조적 구상화, 설계, 교육과 훈련, 공간 탐험, 오락과 같은 많은 분야에 응용될 수 있다.