• Economic and Environmental Geology
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• v.48 no.5
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• pp.391-400
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• 2015

Korea is a global steel producer and a major consumer while iron ore producing is very low compared to the demand. On the other hand, North Korea holds tremendous amount of iron reserves and, however, its producing rate is limited. Moreover, the data regarding mineral resources of North Korea is very limited and uncertain because of political isolation. This study estimated the amount of iron ore resource and production amount for the Musan Iron mine, the world-known open-pit mine of North Korea, using satellite imagery(Landsat MSS, ASTER) and digital maps between 1976 to 2007. As a result, the mining area of Musan mine was increased by $6.1km^2$ during the 30 years and the mining sector was estimated as $4.9km^2$. We estimated the iron resources and production amount of 0.7 and 0.2 billion metric tons, respectively based on 3D modeling and average iron ore density of Anshan formation in China. This amount indicates 8.1 million tons of annual average production and it coincides well with previous reports. We expect this study would be utilized significantly on inter-Korean exchange programs by providing trustable preliminary data.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.4
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• pp.403-410
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• 2012

Purpose: The purposes of this study are to investigate accommodative response among emmetropes, spectacle wearer and contact lens wearer, and correlation between refractive error and accommodative respons for each group. Methods: The 72 subjects(144 eyes) who do not have any ocular diseases were participate in this study. Subjects were categorized into emmetropes, spectacle wearer and contact lens wearer by refractive error using closed-field auto-refractometer. We measured dominant eye, naked/habitual visual acuity and refractive error of monocular/binocular vision of refractive error for far/near distance with open-field auto-refractometer and calculated accommodative lag. Results: There were no significant difference of accommodative lag between right and left eye dominant and non-dominant eye, monocular and binocular vision, and spectacle lens wearer and contact lens wearer, However the accommodative lag of binocular vision was severe than monocular vision at near. The lag of myopia was larger than emmetropes, and male was larger than female. Significant correlation was found between refractive error and accommodative lag in total subjects and the same result was found in emmetropes and contact lens wearer. However there were no significant correlation in the spectacle wearer. Conclusions: There were significant difference between emmetrops and myopes in terms of accommodative lag, however accommodative lag of spectacle wearer was not different with contact lens wearer in myopes. There were also significant correlation between refractive error and accommodative lag in emmetropes and contact lens wearer, but the accommodative lag of spectacle wearer was not significantly correlated with refractive error.

• Informatization Policy
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• v.25 no.2
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• pp.67-83
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• 2018

This study explores how social media influences individual's social development and well-being. Social media is discussed as an effective tool when individuals lacking social and psychological resources are trying to expand their social networks. This study focuses on the social media use of North Korean defectors, who, in general, have closed social media networks in the South Korean society. This study tries to analyze empirically the effect of social media use on North Korean defectors' satisfaction with our society. In particular, this study focuses on how the use of social media influences satisfaction with their life in South Korea at different levels of their emotional states. This study explores that the relationship between social media and satisfaction with their life in South Korea varies based upon the degree of self-esteem and anxiety. This study expects that social media might provide greater benefits for those who are experiencing low self-esteem and high anxiety. In addition, this study conducts the same analysis for the general public and then compares its results with the survey on North Korean defectors. According to the results of North Korean defectors' survey, the impact of social media use on satisfaction with their life in South Korea was greater for those with high anxiety than for those with low anxiety. Meanwhile, the impact was greater for those with high self-esteem than for those with low self-esteem.

• KDI Journal of Economic Policy
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• v.36 no.2
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• pp.175-196
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• 2014

This paper is a theoretical attempt to analyze and understand Yeonjulmang and Yeongyeolmang, which are terms for social networks with negative and positive connotation respectively in Korean Sociology. To do that, we analyze a social network where unilateral help are reciprocated. A social network in this context is a network where the past behaviors of its members are transmitted. With the information how the members behaved before, a social norm can emerge in the network, which facilitate the indirect reciprocation of unilateral help. In this norm, an agent's helping now will be rewarded by his being helped in the future. Since the reward happens in the future, this norm may not be sustained even if it is efficient. To sustain the reciprocation of the help, a norm can evolve to punish the violation of the norm more severely. If the punishment becomes too severe, the reciprocation of the help can be sustained even if it is not efficient any more in that the cost of help exceeds the benefit. If we allow the exit of the network, members have incentive to do it as belonging to the network is not beneficial any more. Then the social network may collapse. To avoid the collapse of the network, the exclusive norm, which exclude even mutually beneficial relationship with outsiders, may emerge. This can explain the emergence of Yeonjulmang, or a closed network, which is inefficient in double senses; 1) it may sustain inefficient reciprocation of help, and 2) the mutually beneficial relationship is excluded between an insider and an outsider of the network.

• Applied Microscopy
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• v.29 no.1
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• pp.83-94
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• 1999

The ultrastructure of small arterioles and capillaries in the lumbrical muscles of rat digits were studied by electron microscopy and following results were obtained. 1. The diameter of small arterioles of rat digits were $12\sim20{\mu}m$, and it was relatively smaller than human $(30\sim35{\mu}m)$. 2. All the endothelial cells of small arterioles and capillaries in the lumbrical muscles of rat digits were continuous type, and they had typical morphological characteristics of continuous endothelial cells : numerous cytoplasmic pinocytic vesicles and many tight junctions between the endothelial cells. 3. In the small arterioles subendothelial layers were irregularly spaced beneath the basal lamina, and membrane to membrane contacts were found between the endothelial cells and smooth muscle cells. 4. Pericytes were often found nearby capillary endothelium, and their cytoplasmic processes surrounded part of endothelial cells. They were enclosed by basal lamina. 5. Smooth muscle cells in tunica media of small arterioles were only one layered, that is, they were terminal arterioles. Sarcoplasm of smooth muscle cell was divided to 2 areas; homogeneous or filamentous area and non-homogeneous perinuclear area. 6. The tunica adventitia contained fibroblasts with extremely attenuated cytoplasmic processes and collagen fibirls.

• The Journal of Engineering Research
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• v.1 no.1
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• pp.23-30
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• 1997

Energy transfer by free convection arises in many engineering applications, such as a hot steam radiator for heating a room, refrigeration coils, electric transformers, heating elements and electronic equipments. Generally unsteady natural convection flow in a horizontal channel with arbitrary wall temperatures and the mathematical and physical basis of convection transport has been considered in general. A physically meaningful exact solution of the problem has been obtained in a closed form by the application of the standard finite sine transform technique. Influences of the governing parameters, the Prandtl number and the Rayleigh number, to bring the flow and heat transfer to final steady states have been discussed separately. For constant values of the arbitray wall temperatures and of the function, determining the average axial velocity, the final steady state is approached in different times respectively for the cases when the Prandtl number Pr>1 and Pr<1. It is also seen that the function, representing the axial temperature gradient, is influenced by none of the governing parameters : but the steady state flow is influenced only by the Rayleigh number. There are, of course, many applications. Free convection strongly influences heat transfer from pipes and transmission lines, as well as from various electronic devices. It is also relevant to the environmental sciences, where it is responsible for oceanic and atmospheric motions, as well as related heat transfer processes.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.4
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• pp.256-264
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• 2014

This study was carried out to estimate the benthic environments and polychaetous community in Garolim Bay, through five field surveys from April 2006 to April 2007. Garilim Bay is a semi-enclosed bay and composed of a biramous tidal channel and nearby wide tidal flats. Surface sediment in the inner bay was composed of fine grained particles whereas that in the mouth area of bay was of coarse grained ones. Benthic polychaete worms were the most dominant taxa occupying 65.1% of total benthic macrofauna. Species number was higher in the inner bay than mouth and outer area of bay, and in the bay higher on the tidal flat than channel area. Density was higher on the tidal flat than channel area. Dominant polychaetous species were Prionospio sp., Heteromastus filiformis, Lumbrineris longifolia and so on, which is known as opportunistic species. Prionospio sp. and H. filiformis inhabited mainly on the tidal flats in inner bay, while L. longifolia in the channel area and mouth of the bay. Cluster analysis and nMDS showed the typical inner-to-outward distribution of station groups, which indicated the sequential difference of the species composition of each station group. To assess the benthic healthiness of Garolim Bay by AMBI and BPI analysis, the benthic condition was analyzed from slightly polluted in the outer and mouth of the bay to moderately polluted in the inner bay. Assumed from dominant species composition and benthic healthiness condition, benthic environments of Garolim Bay was slightly unstable and disturbed and organic enrichment was currently underway by massed fisheries farms.

• Convergence Security Journal
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• v.18 no.1
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• pp.143-155
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• 2018

The purpose of this study is to extract the failure attributions to identify the failure factors of the security guards and to derive the risk factor factors through failure cases analysis. Failure attributions were prepared by using semi-structured questionnaires(17) and closed questionnaires(179) starting from the fully open questionnaires(8), and processed through SPSS 21.0 and AMOS 21.O statistical packages. As a result of summarizing the causal relationship between the failure attribution and the failure case (patrol failure pattern factor), In Park Jung-Hee's assassination, lack of experience(2), negative mind(1), lack of work ability(1), lack of experience(2), organizational non-system activeness(2), lack of awareness of mission(1) Failure(2), lack of consciousness(2), and 14 failure patterns were found. Aung-San National Cemetery explosion occurred in eight failure patterns including insecurity(1), negative mind(1), lack of work skills(2), lack of experience(2), individualism(1), There were eight failure patterns in the case of Mr. Yook Young-Su 's sniping, including insincerity(2), negative mind (1), lack of experience(2), lack of awareness of mission(2) and failure to share work(1).

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.1
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• pp.38-47
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• 2019

The most common cause of mouth breathing is obstacles caused by mechanical factors in upper airway. Mouth breathing could be consequently pathological cause of sleep-disordered breathing. Sleep-disordered breathing in children can cause growth disorders and behavioral disorders. The purpose of this study was to investigate relationship between upper airway and sleep-disordered breathing in children with mouth breathing. Twenty boys between 7 - 9 years old who reported to have mouth breathing in questionnaire were evaluated with clinical examination, questionnaires, lateral cephalometric radiographs, and portable sleep testing. This study assessed apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) for the evaluation of sleep-disordered breathing and was done to investigate the correlation between these values and the upper airway width measured by lateral cephalometric radiographs. There was no significant correlation with the size of the tonsils (p = 0.921), but the adenoid hypertrophy was higher in the abnormal group than in the normal group (p = 0.008). In the classification according to AHI and ODI, retropalatal and retroglossal distance showed a statistically significant decrease in the abnormal group compared to the normal group (p = 0.002, p = 0.001). As AHI and ODI increased, upper airway width tended to be narrower. This indicates that mouth breathing could affect the upper airway, which is related to sleep quality.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.470-478
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• 2023

All people have human rights that should be protected, and today, the importance of protecting human rights is emphasized in all areas of society. The industry is also carrying out activities to protect the human rights of workers, such as implementing human rights education for human rights management and preparing a response system for human rights violations. However, due to the closed environment and special working conditions, seafarers on board are often placed in a blind spot in human rights protection. In particular, a number of cases of human rights violations concerning beginner seafarers, including cadets, have been identified, and relevant research is insufficient compared to other occupational groups. Jobs that restrict basic human rights cannot be envied by anyone. In this study, implications and problems were derived based on the results of a human rights survey of cadets, and cases of human rights violations, and improvement measures were proposed. The cadets had a very negative perception of human rights violations before boarding. However, it was found that their perception changed after boarding. It was confirmed that cadets have unnecessary fears and concerns before boarding. Improvement measures include the establishment of a legal system for the status of cadets, measures to alleviate non-physical human rights violations, improvement of human rights violations handling procedures and response systems, and enhancing the effectiveness of human rights education.