• Ocean Systems Engineering
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• v.12 no.1
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• pp.87-142
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• 2022

An analysis for the computation of Fatigue Damage Index (FDI) under the effects of the various combination of the ocean loads like random waves, current, platform motion and VIV (Vortex Induced Vibration) for a certain design water depth is a critically important part of the analysis and design of the marine riser platform integrated system. Herein, a 'Computer Simulation Model (CSM)' is developed to combine the advantages of the frequency domain and time domain. A case study considering a steel catenary riser operating in 1000 m water depth has been conducted with semi-submersible. The riser is subjected to extreme environmental conditions and static and dynamic response analyses are performed and the Response Amplitude Operators (RAOs) of the offshore platform are computed with the frequency domain solution. Later the frequency domain results are integrated with time domain analysis system for the dynamic analysis in time domain. After that an extensive post processing is done to compute the FDI of the marine riser. In the present paper importance is given to the nature of the current profile and the VIV. At the end we have reported the detail results of the FDI comparison with VIV and without VIV under the linear current velocity and the FDI comparison with linear and power law current velocity with and without VIV. We have also reported the design recommendations for the marine riser in the regions where the higher fatigue damage is observed and the proposed CSM is implemented in industrially used standard soft solution systems (i.e., OrcaFlex^*TM and Ansys AQWA^**TM), Ms-Excel^***TM, and C++ programming language using its object oriented features.

• The Korean Journal of Air & Space Law and Policy
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• v.25 no.1
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• pp.205-236
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• 2010

This article deals with international space law for the environmental protection in outer space especially for space debris arising from space activities. After studying 1967 Outer Space Treaty, 1968 Rescue Agreement, 1972 Liability Convention, 1975 Registration Convention and 1979 Moon Agreement, we could find few provisions dealing with space environment in those treaties. During the earlier stages of the space age, which began in the late 1950s, the focus of international law makers was the establishment of the basic rules of space law governing the states' activities in outer space. Consequently the environmental issues and the risks that might arise from the generation of the space debris did not receive priority attention within the context of the development international space law. Although the phrases such as 'harmful contamination', 'harmful interference', 'disruption of the environment', 'adverse changes in the environment' and 'harmfully affecting' in relation to space environment were used in 1967 Outer Space Treaty and 1979 Moon Agreement, their true meaning was not definitely settled. Although 1972 Liability Convention deals with compensation, whether the space object covers space debris is unclear despite the case of Cosmos 954. In this respect international lawyers suggest the amendment of the space treaties and new space treaty covering the space environmental problems including the space debris. The resolutions, guidelines and draft convention are also studied to deal with space environment and space debris. In 1992 the General Assembly of the United Nations passed resolution 47/68 titled "Principles Relevant to the Use of Nuclear Power Sources in Outer Space" for the NPS use in outer space. The Inter-Agency Space Debris Coordination Committee; IADC) issued some guidelines for the space debris which were the basis of "the UN Space Debris Mitigation Guidelines" approved by COPUOS in its 527th meeting. In 1994 the 66th conference of ILA adopted "International Instrument on the Protection of the Environment from Damage Caused by Space Debris". Although those resolutions, guidelines and draft convention are not binding states, there are some provisions which have a fundamentally norm-creating character and softs laws.

• Journal of The Korean Astronomical Society
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• v.27 no.1
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• pp.45-53
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• 1994

We present the calculation of X -ray spectra produced through Compton scattering of soft X-rays by hot electrons in the spherical shell geometry, using fully relativistic Monte Carlo simulation. With this model, we show that the power-law component, which has been observed in the low luminosity state of low-mass X-ray binaries (LMXBs), is explained physically. From a spectral. analysis, we find that spectral hardness is mainly due to the relative contribution of scattered component. In addition, we see that Wi en spectral features appear when the plasma is optically thick, especially in the high energy range, $E{\gtrsim}100keV$. We suggest that after a number of scattering the escape probability approaches an asymptotic form depending on the geometry of the scattering medium rather than on the initial photon spectrum.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.447-449
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• 1996

The main objective of this paper is to increase the efficiency, to eliminate the harmonics wave and to acomplish the zero voltage regulation of the output voltage. To accomplish the goal, DC-to-DC converter model with ERS(Energy Recovery Snubber) is developed. And, to realize the detail purpose, we are used ZVS soft switching snubber, ripple steering filter and, function control law etc.. So, we presented to show superior operation of this convertor with the zero voltage regulation function.

• Journal of Environmental Science International
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• v.13 no.11
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• pp.1001-1007
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• 2004

The rapid industrialization and urbanization in Osaka Bay have produced many serious water pollution problems since the 1960s. A symbolic phenomenon is algae bloom (red tide), which occurred 53 times in 1976. The special law was enacted in 1973 and a number of administrative steps were taken, such as cutting COD loading, reductions in phosphorus (P) and restriction of land reclamation. As a result, the pollution of Osaka Bay has gradually been reduced, and the environment has been improved to some extent. In this study, to analyze the relations between water qualities as well as a social, economic activity by the coastal zone, the water quality data in Osaka Bay of 70 years past since 1921 were collected. Data such as population, livestock, fertilizer, industrial product etc. were also collected for estimating nutrients flowing into bay from land. It was found that the water quality was changed of a similar trend of estimated nutrients load, with delay of about four or five years.

• Structural Engineering and Mechanics
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• v.24 no.1
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• pp.31-50
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• 2006

This paper deals with the mechanical behaviour of the thin-walled cylindrical air-spring shell (CAS) made of rubber-textile cord composite (RCC) subjected to different types of loading. An orthotropic hyperelastic constitutive model is presented which can be applied to numerical simulation for the response of biological soft tissue and of the nonlinear anisotropic hyperelastic material of the CAS used in vibroisolation of driver's seat. The parameters of strain energy function of the constitutive model are fitted to the experimental results by the nonlinear least squares method. The deformation of the inflated CAS is calculated by solving the system of five first-order ordinary differential equations with the material constitutive law and proper boundary conditions. Nonlinear hyperelastic constitutive equations of orthotropic composite material are incorporated into the finite strain analysis by finite element method (FEM). The results for the deformation analysis of the inflated CAS made of RCC are given. Numerical results of principal stretches and deformed profiles of the inflated CAS obtained by numerical deformation analysis are compared with experimental ones.

• Journal of Aerospace System Engineering
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• v.8 no.2
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• pp.1-6
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• 2014

Currently outer space become more and more congested and contested, according to the increase of satellites, nations and government consortia that operate satellites, and commercial and academic satellite operators. Therefore, international community, including the United Nations has been making a greater effort to adopt non-legally binding international documents capable of regulating space activities for the purpose of the security, safety and long-term sustainability of space activities. These are a draft International Code of Conduct for Outer Space Activities(ICoC) and UN Group of Governmental Experts on Transparency and Confidence-Building Measures in Outer Space Activities(UNGGE).

• The Research Journal of the Costume Culture
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• v.7 no.1
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• pp.82-99
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• 1999

The purpose of this study was to investigate the traditional costume colors in ancient Korea. The results of this study can be summarized follows : The traditional costume colors in ancient Korea was affected on Chineses goverment official\`s costume colors, specially in Tongil Silla Dynasty. Goverment official\`s costume colors were purple(紫), red(赤), yeoolw(黃), blue(靑). The traditional Korean colors for clothes were devided in the white costume for low class and the colored costume of high class. The traditional Korean colors for colthes became fixed in the later Chosun dynasty, According to developing of dyeing technic, the prohibition of red costume for low class made for wear red undercloth. And on account of costume color in sumptuary law occured the transition of costume color. As transition of costume color, yellow(黃) changed in light in light yellow(松花色), purple(紫) did in dark green purple(茶割) Also it was found that the traditional Korean color for clothes was many kinds of soft, deep, natural colors out of red(紫)·yellow(黃)·white(白)·black(黑)·blue(靑).

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.599-601
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• 2015

The short time scale X-ray variability associated with the accretion disk around compact objects is complex and is vaguely understood. The study of the cross correlation function gives an insight into the energy dependent behavior of the variations and hence connected processes. Using high resolution RXTE data, we investigate the dynamical cross correlation function of an observation of a black hole source XTE J1550-564 in the steep power law state. The cross correlation between soft and hard X- ray energy bands revealed both correlated and anti-correlated delays (${\leq}{\pm}15s$) on a correlation time scale of 50 s. It was noticed that the observed delays were similar to the delays between X-ray and optical/IR bands in other black hole and neutron star sources. We discuss the possible mechanisms/processes to explain the observed delays in the dynamical CCF.

• Steel and Composite Structures
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• v.32 no.2
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• pp.253-264
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• 2019

This paper presents the combination resonances of FG porous (FGP) cylindrical shell under two-term excitation. The effect of structural damping on the system response is also considered. With regard to classical plate theory of shells, von-$K{\acute{a}}rm{\acute{a}}n$ equation and Hook law, the relations of stress-strain is derived for shell. According to the Galerkin method, the discretized motion equation is obtained. The combination resonances are obtained by using the method of multiple scales. Four types of FGP distributions consist of uniform porosity, non-symmetric porosity soft, non-symmetric porosity stiff and symmetric porosity distribution are considered. The influence of various porosity distributions, porosity coefficients of cylindrical shell and amplitude excitations on the combination resonances for FGP cylindrical shells is investigated.