• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.5
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• pp.749-760
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• 2017

Recently, the proportion of tunnel structures in roads and railways has increased rapidly. Along with this trend, the rate of occurrence of cracks and dropouts in concrete lining of tunnel structures is increasing. Generally, maintenance of such concrete lining is normalized and managed as the core of maintenance work in tunnel maintenance. However, the maintenance of the tunnel pavement is important in securing driver in the tunnel. In the design of tunnels, the underground condition of the tunnel is designed to be in good rock condition, so there have not been many cases of cracks in the tunnel pavement in the past. Recently, the construction of tunnel structures has been rapidly increased, and the length of the tunnels has become longer.Tunnel pavement installed in these ground conditions is increasing the occurrence of cracks in the pavement due to decrease of bearing capacity of the pavement after a long time. In this study, FWD and GPR were conducted to analyze the types of cracks and the reduction of bearing capacity in the tunnel.

• The Journal of the Petrological Society of Korea
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• v.18 no.3
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• pp.211-221
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• 2009

This study illustrates the relationship between the petrographic characteristics of micrographic granite and the topographic features around Ijin-ri. Light-brown to light- gray granite is composed of intergrown fine-grained quartz + orthoclase, displaying micrographic textures. Miarolitic cavities are abundant. Many micro-landforms including tor, tafoni, and gnamma occurred in the micrographic granite of the study area. Tafoni is dominant in the north and gnamma is dominant in south. From our study of the occurrence and textural properties, two alteration zones were clearly identified; one is an external zone (A) characterized by abundant of small sized miarolitic cavities and the other is an internal zone (B) having them less than zone A. The former is dominant in north, and the latter is dominant in south. Particular geomorphologic features such as fluting cores and raised rims are present in the Ijin-ri area. This suggests that development of miarolitic cavities played an important role in the formation of the various geomorphologic features. Consequently, the petrogenesis of the micrographic granite is related to geomorphologic features in the external zone typified by abundant tafoni such as the tiger rock, and the formation of a platform as micro-landforms is influenced by thetextural differences of host rock in the internal zone.

• Spatial Information Research
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• v.19 no.6
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• pp.19-28
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• 2011

Recently, the interests of marine mineral resources has been increasing from the depletion of land resources around the world and many countries are involving in marine exploration work. South Korea is also currently performing exploration work to estimate the marine mineral resources around the Korean Peninsula. However, massive amounts of marine exploration data accumulated from the long-term exploration work have not been systematically managed. The data have been managed by the file based system instead of commercial database. The aim of this study is to construct GIS-based Marine Mineral Resource Information System using a spatial database for the core sediments of the marine exploration data. For constructing such DB system, GIS-based data items were classified, and a database was designed using relational database model. The database was constructed using commercial DBMS(Database Management System), Oracle. Also, necessary functions of the system were defined for the effective use of database based on users' requirement analysis. The GIS-based Marine Mineral Resource Information System has enabled to support the systematic management of the marine exploration data. Furthermore, it is expected that this spatial database will be useful in estimating the reserves of the mineral resources and provide valuable information for economic evaluation. In the future, the application of advanced techniques of spatial analysis and 3-dimensional display function will be required.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.6
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• pp.305-311
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• 2012

In order to recycle the coal bottom ashes (denoted as BA) produced from a thermal power plant, the artificial aggregates (denoted as AAs) containing BA and red clay were manufactured, and the physical properties of AAs were studied as a function of particle size of BA and batch compositions. As-received BA had 38 wt% coarse particles of above 2 mm and many unburned carbon mass and porous slag particles were co-existed. So the two particle sizes of BA, the fine (< 100 ${\mu}m$) and coarse (< 2 mm), were prepared by milling and screening process. The AAs containing fine BA sintered at $1100{\sim}1200^{\circ}C$ had the higher bulk density and lower water absorption compared to the specimen made of coarse BA. The inside core of AAs manufactured by using coarse BA showed nonuniform and porous microstructure, while the AAs made of fine BA had a uniform and dense microstructure. In this research, the AAs containing BA and red clay with various bulk density (1.2~1.7) and water absorption (13~21 %) could be manufactured by controlling the particle size of BA and batch compositions, so the AAs of various physical properties could be applied to the wide fields such as construction/building materials in near future.

• Korean journal of communication and information
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• v.22
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• pp.167-210
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• 2003

This study examined the organizational status of female employees in three major over-the-air broadcasting companies in South Korea in terms of both formal and informal organizational structures. Quantitative and qualitative analyses were conducted for the data collected through the official statistical documents on Korean broadcasting industries, in-person/telephone interviews, and survey. The results show that the proportion of female employees in the three major over-the-air broadcasting companies remained relatively unchanged at about as low as 10 per cents during the past 10 years, Furthermore, most of them are positioned in the lower hierarchical positions. The informal organizational status of female employees in terms of informal organizational culture, informal network, and mentoring, also reveals inequal conditions in many respects. Concerning role assignments, no significant evidence of sexual discrimination was found. Discrimination against women in assigning core roles such as political and economic news reporting and drama producing, however, was still prevailing. Currently, a marked increase of female proportion is observed among newly hired reporters, producers, and announcers. In the long term, these trends can bring positive changes in the status of female employees in the broadcasting industry organization.

• Journal of The Korean Astronomical Society
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• v.33 no.2
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• pp.111-121
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• 2000

Many models of globular cluster formation assume the presence of cold dense clouds in early universe. Here we re-examine the Fall & Rees (1985) model for formation of proto-globular cluster clouds (PGCCs) via thermal instabilities in a protogalactic halo. We first argue, based on the previous study of two-dimensional numerical simulations of thermally unstable clouds in a stratified halo of galaxy clusters by Real et al. (1991), that under the protogalactic environments only nonlinear (${\delta}{\ge}1$) density inhomogeneities can condense into PGCCs without being disrupted by the buoyancy-driven dynamical instabilities. We then carry out numerical simulations of the collapse of overdense douds in one-dimensional spherical geometry, including self-gravity and radiative cooling down to T = $10^4$ K. Since imprinting of Jeans mass at $10^4$ K is essential to this model, here we focus on the cases where external UV background radiation prevents the formation of $H_2$ molecules and so prevent the cloud from cooling below $10^4$ K. The quantitative results from these simulations can be summarized as follows: 1) Perturbations smaller than $M_{min}\~(10^{5.6}\;M{\bigodot})(nh/0.05cm^{-3})^{-2}$ cool isobarically, where nh is the unperturbed halo density, while perturbations larger than $M_{min}\~(10^8\;M{\bigodot})(nh/0.05cm^{-3})^{-2}$ cool isochorically and thermal instabilities do not operate. On the other hand, intermediate size perturbations ($M_{min} < M_{pgcc} < M_{max}$) are compressed supersonically, accompanied by strong accretion shocks. 2) For supersonically collapsing clouds, the density compression factor after they cool to $T_c = 10^4$ K range $10^{2.5} - 10^6$, while the isobaric compression factor is only $10^{2.5}$. 3) Isobarically collapsed clouds ($M < M_{min}$) are too small to be gravitationally bound. For supersonically collapsing clouds, however, the Jeans mass can be reduced to as small as $10^{5.5}\;M_{\bigodot}(nh/0.05cm^{-3})^{-1/2}$ at the maximum compression owing to the increased density compression. 4) The density profile of simulated PGCCs can be approximated by a constant core with a halo of $p{\infty} r^{-2}$ rather than a singular isothermal sphere.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.678-699
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• 2015

Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for nearterm human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement) for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER), for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of $100MW_{th}$ and an electricity generation mode of $100MW_{th}$, equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and thermohydraulics was carried out. The result indicates that the innovative design has great potential for high propellant efficiency and thrust-to-weight of engine ratio, compared with the existing NTR designs. However, the build-up of fission products in fuel has a significant impact on the bimodal operation of the moderated reactor such as xenon-induced dead time. This issue can be overcome by building in excess reactivity and control margin for the reactor design.

• Journal of Sasang Constitutional Medicine
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• v.10 no.2
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• pp.15-28
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• 1998

One's constitution is formed congenitally and is also acquired, and is relatively stable in its individually manifested function, structure and temperament. It has characteristics of universality, complexity, generality and continuity. It is also manifested in physiological responses and expresses pathologic tendencies including susceptibility. Attempts at understanding constitution has had a long history throughout the world. In Oriental Medicine, the constitution had been acknowledged from the "Huangdi Neijing", which has been a bible in Oriental Medicine for about two thousand years. In many aspects, the "Huangdi Neijing" provides the basis for both basic and practical fields. In order to derive the ideal structure from the "Huangdi Neijing" to Lee Je-ma's(Lee Jayma's) Sasang Constitutional ideas, which can strengthen the understanding of ideal core of Oriental Medicine's constitutional characteristics, the author launched his analysis of the constitutional understandings in the "Huangdi Neijing" as a first step and came to the following: 1. The constitutional understanding in the "Huangdi Neijing" was done both via the physiological responses to heat, pain and acupuncture treatment and the pathologic tendencies via body structure, strength, body heat, courage and obesity. 2. It was recognized that the constitution was formed congenitally and also acquired factors like living conditions including food customs, residents and geographical conditions were explained in detailed. 3. The constitutional typology was suggested both by the general and systematic criterion according to the Yin-yang and the Five phase theories and by single criterion such as obesity, courage and the response to acupuncture treatment. 4. As diagnosis is related to the constitution, courage was adopted for the disease caused by emotions, obesity was for its manifestations of qi and blood, the quantities of qi-blood and Yin-yang in the typology by the Yin-yang and Five phase theories were suggested. 5. In the case of obesity, Yin-yang and Five phase theory, treatment according to the constitutional ideas was mentioned, and their goals were concluded as "being the balancing between Yin and Yang" which means the Yin-yang theory is more practical than the Five phase theory in Oriental Constitutional Medical field. According to the above understandings, the author would like to suggest that the constitutional ideas in the "Huangdi Neijing" based on the Yin-yang theory blossomed via the practical spirit of Zhang Zhong-jing's "Shanghanlun" and at last from Lee Je-ma's(Lee Jayma's) Sasang Constitutional Medicine which realized "the balancing between Yin and yang" through the practical applications of herbal treatments.

• Journal of Life Science
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• v.22 no.9
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• pp.1173-1179
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• 2012

The importance of genetic stability and bio-safety in the environment has recently been recognized for many (genetically modified) GM plants. This study evaluated the GM safety of transgenic rice and its environmental variance. Data on agronomic characters and principal component were collected for vitamin A-enriched GM rice and four check cultivars in a large GM field trial during 2009-2011. The cultivation environment was a large GM field and a greenhouse. In this experiment, there was no significant difference between the agronomic characters of the GM rice and those of a donor plant, 'Nagdong'. In terms of grain characteristics, the appearance and physicochemical characteristics of the GM rice and those of the donor plant were similar. However, the grain of the GM rice developed a white core and a white belly when planted in the greenhouse. The type and distribution of dominant weed species were not different in the GM rice and the 'Nagdong'. In addition, gene flow was not detected in the dominant weed species based on PCR analysis.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2002.11a
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• pp.301-306
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• 2002

In Japan, the vacancy rates of office buildings have been at high in big cities since 1992. This problem is especially acute in Tokyo, where it is estimated that over 2.27 million square meters of office floor area will be oversupplied in 2003: big urban redevelopment projects will be completed in 2003. Under these circumstances, International Cooperative Research and Development on Sustainable Urban Management by Conversion of Buildings, called “SUMCOB”, has been carried out. This research aims to regenerate urban areas by converting redundant offices into flats, although instances of conversion are still very few in Japan. This paper introduces part of current results by SUMCOB, and discusses legal problems with conversion and basic capacity of vacant offices in Tokyo. It has been confirmed that there are no constraints concerned with Real Estate Registration Law (although it requires the change of the registration after conversion). and City Planning Law. However, some criteria are incompatible with Building Standard Law and Fire Service Law if the use of the building is changed from offices to flats. Typical incompatibility between offices and flats is lightening. If the buildings do not satisfy criteria for flats, the cost of renovation works for conversion will increase. To examine the basic capacity of vacant office buildings for conversion, field surveys in Tokyo have carried out at three areas: Kodenmacho (Chuo-ku), Toranomon (Minato-ku), and Iwamonocho (Chiyoda-ku). They are typical office areas that are included in center core of Tokyo. In Chuo-ku, the oldest commercial area in Tokyo, textile merchants have been located their headquarters. In Minato-ku, many rental office buildings have been located and several large scale redevelopments are advancing. Chiyoda-ku includes Marunouchi area, which is the prime office area in Japan. Thirty percent of the buildings in survey areas suffer from over twenty percent vacant floor rate, and fifty five percent were constructed before 1990. Especially most of buildings over forty percent vacant floor rate were constructed in 1980s. Vacant office problems haven't been seen in old buildings in Tokyo yet. The number of dwelling units made from office space will influence the conversion scheme. Seventy percent of the office buildings in survey areas have floor area of less than two hundred square meters. If they have been subdivided into two bedrooms type or three bedrooms type, the number of dwelling units in a floor would be less than three. The difficulty of conversion planning derives from frontage size, depth size, and their proportion. The five categories are proposed to grasp actual requirements for converting offices into flats.