• Advances in nano research
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• v.14 no.6
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• pp.575-590
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• 2023

Many of small-scale devices should be designed to tolerate high temperature changes. In the present study, the states of buckling and stability of nano-scale cylindrical shell structure integrated with piezoelectric layer under various thermal and electrical external loadings are scrutinized. In this regard, a multi-layer composite shell reinforced with graphene nano-platelets (GNP) having different patterns of layer configurations is modeled. An outer layer of piezoelectric material receiving external voltage is also attached to the cylindrical shell for the aim of observing the effects of voltage on the thermal buckling condition. The cylindrical shell is mathematically modeled with first-order shear deformation theory (FSDT). Linear elasticity relationship with constant thermal expansion coefficient is used to extract the relationship between stress and strain components. Moreover, minimum virtual work, including the work of the piezoelectric layer, is engaged to derive equations of motion. The derived equations are solved using numerical method to find out the effects of temperature and external voltage on the buckling stability of the shell structure. It is revealed that the boundary condition, external voltage and geometrical parameter of the shell structure have notable effects on the temperature rise required for initiating instability in the cylindrical shell structure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.103-109
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• 2004

As GNP increases, many peoples need the seafood with high quality. In Korea, aquaculture is one cf major incomes for fishing households and records $50.6\%$ of total incomes for domestic fishery. The loss of aquaculture farm due to thievery at sea increases every year. In this research, we propose the system model for development of radar surveillance system, which protects aquaculture farms. For the proposed system, general requirements are described. Our system is cost-effective when it is applied to domestic fishing households.

• Korean Journal of Materials Research
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• v.12 no.10
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• pp.784-790
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• 2002

For mass product of nanocrystalline ZnO ultrafine powders, self-sustaining combustion process(SCP) and ultrasonic spray combustion method(USCM) were applied at the same time. Ultrasonic spray gun was attached on top of the vertical type furnace. The droplet was sprayed into reaction zone of the furnace to form SCP which produces spherical shape with soft agglomerate crystalline ZnO particles. To characterize formed particles, fuel and oxidizing agent for SCP were used glycine and zinc nitrate or zinc hydroxide. Respectively, with changing combustion temperature and mixture ratio of oxidizing agent and fuel, the best ultrasonic spray conditions were obtained. To observe ultrasonic spray effect, two types of powder synthesis processes were compared. One was directly sprayed into furnace from the precursor solution (Type A), the other directly was heated on the hot plate without using spray gun (Type B). Powder obtained by type A was porous sponge shape with heavy agglomeration, but powder obtained using type B was finer primary particle size, spherical shape with weak agglomeration and bigger value of specific surface area. 9/ This can be due to much lower reaction temperature of type B at ignition time than type A. Synthesized nanocrystalline ZnO powders at the best ultrasonic spray conditions have primary particle size in range 20~30nm and specific surface area is about 20m$^2$/g.

• Economic and Environmental Geology
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• v.23 no.3
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• pp.309-322
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• 1990

The accelerated industrialization of Korean economy over the last couple of decades has brought an era of mass consumption of mineral commodities. This increased consumption has been satisfied mainly by imports from abroad. South Korea has about 50 useful mineral commodities for the mineral industry, among 330 kinds of minerals described. In 1988 the self-sufficiency ratio of domestic demand for 44 non-fuel(metallic and non-metallic) minerals as a whole was no more than 29 percent. The ratio for 26 non-metallic minerals was much higher, about 66 percent. On the other hand, the ratio for 18 metallic minerals was relatively very low, about 6.3 percent. The correlation between GNP and mineral consumption in South Korea shows well the slow down patterns during the last two decades.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.5
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• pp.815-836
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• 1999

The role of animal agriculture for the quality of human life has always been emphasized during 20th century and it is expected to be even more important in terms of food supplies and in providing additional functions in the future. The world human population has almost tripled during a period of half century. The world population of animals has increased 2~3 times (6 times for chicken) during the last 60 years, and the total amount of livestock products has increased 5~6 times (more than 10 times in pork) with higher annual growth rate (9%) in developing countries. Increased personal income certainly encouraged demand for animal products over grains and lower animal production costs resulted from scientific and technological advances. Similarly the production of total grains has more than doubled owing to the advances in agricultural science during the later part of the 20th century. The average life span of world people in 1950s was only 46 years, which will be increased to almost 66 years in the year 2000. Present date clearly indicate that the life span of people is proportional to their income (GNP) and/or animal protein intake. Animals can provide other resources than foods. The increase of human population indicates that the number of animals as well as per capita consumption of animal products will be increased in the 21st century. The other resources we get from animals are drafts, packing, riding, hunting and herding. Guiding the blind, protection and companionship are also examples of what we can expect from animals. In the very near future, animals will become major donors of organs, skin and producers of drugs or special functional foods. It may be concluded that animals are very closely associated and related to the quality of human life, and they are expected to remain the same way in the 21st century.

• Environmental and Resource Economics Review
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• v.8 no.1
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• pp.27-50
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• 1998

본 논문은 지구의 지속적인 발전을 위해서 지구환경문제인 지구온난화 방지에 대한 방법으로 이산화탄소 저감을 위한 방안에 관해서 검토하였다. 지속가능성을 위협하고 있는 빈부의 격차를 축소하고 동시에 지구온난화에 대한 환경개선을 국제적인 틀 안에서 환경비교우위에 기초한 산업구조의 조정과 공동이행활동이라고 하는 방안을 제안하고, 이러한 방안에 관해서 분석평가하고 비교한 것이다. 구체적으로는 이산화탄소 문제를 지구 전체 문제라고 가정하고 방안을 강구하였다. 국가간의 GNP와 고용에 미치는 영향은 최소한으로 하면서 이산화탄소 배출량을 줄이는 양국의 산업구조를 명확하게 한 것이다. 더욱이 남북문제도 동시에 해결한다는 것에 착안해서 이론전개를 하고 있다. 따라서, 여기서는 환경비교우위의 개념을 응용해서 부가가치단위당 이산화탄소 배출이 상대적으로 적은 부문(환경적 우위 부문)에 생산을 특화하고 이것과 반대의 환경적 열위부문에 대해서는 상대국으로부터 수입에 의존하는 것에서 국제적으로 이산화탄소 배출이 적은 산업의 재배치를 실현하는 것이 가능하다라고 하는 논리전개로부터 그 결과를 명확하게 하였다. 또한, 지구환경개선을 목표로 하는 또 하나의 전략인 공동이행활동에 관해서 분석하였다. 이것에 관해서는 경제적으로 온실효과가스를 줄인다는 것뿐만 아니라 선진국에서 개발도상국으로의 기술이전을 촉진하고 남북격차를 시정한다는 점에서 기대가 크다는 것에 착안하고 게임이론을 통해 일본과 중국의 실제 데이터를 사용하여 공동이행활동의 가능성을 평가하였다. 이러한 두 가지 방책의 특징을 검토하여 효율적인 방안을 제시하고 그 방안에 대하여 고안하고 시뮬레이션 분석을 하였다. 그 결과 융합방안에서는 상술한 환경비교우위의 정학적 분석결과와 공동이행의 게임분석결과를 고려하고 확장된 공동이행 게임의 균형점까지 자원의 원조를 한다는 전제조건하에서 2010년까지 이산화탄소 배출량 추이를 산정한 결과 융합방안이 보다 효율적이라는 것이 판명되었다. 이러한 내용을 바탕으로 본 논문에서는 현재 지구 온난화 문제의 해결에 있어서 걸림돌이 되고 있는 남북문제의 격차와 협력에 관한 곤란한 문제에 착안해서 환경적 우위와 융합방안이라고 하는 새로운 방안을 제안하였다. 그리고 각각의 방안에 대해서 상세히 분석하고 일본과 중국을 모델로 실제 정책으로의 실현가능성을 분석하였다.

• Journal of the Mineralogical Society of Korea
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• v.7 no.1
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• pp.1-13
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• 1994

The industrial minerals play an important role in mining sector. More than 70 % of total mineral production come from industrial mineral sector. This paper reviews geological occurrence of kaolin, pyrophyllite and limestone, and current demand-supply status of major industrial minerals in the Republic of Korea. The kaolin is mainly distributed in the Kyeongsang province, formed by deep weathering of Precambrian anorthosite on mountainside of gentle slope. The pyrophyllite mainly occurs in the Kyeongsang and Chulla provinces, formed by hydrothermal alteration of late Cretaceous andesitic and rhyolitic rocks. Pyrophyllite comprises massive and lenticular bodies and contains minor amounts of kaolin, alunite and pyrite, in some places andalusite and illite. The limestone(Great Limestone Series of Cambrian age) is distributed widely in the Kwangwon and Chungcheong provinces. The limestone bodies are approzimately 70 km long and 3 km wide, elongated NE-ward, and show high grade of CaO content. In 1992, the self-sufficiency ratio of 44 nonfuel (metallic and non-metallic) minerals was no more than 30 percent. However, the ratio of 27 industrial minerals (non-metallic) represents high value of about 72 percent. The export/productjon ratio of the industrial minerals shows decreasing patterns from 12.2 % in 1983 to 4.2 % in 1992. Also the import/production ratio shows rapidly decreasing pattern from 84 % in 1983 to 38.2 % in 1992.

• Journal of the Korean Institute of Navigation
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• v.9 no.1
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• pp.1-40
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• 1985

The transport of cargoes carried by coastal and ocean-going vessels has increased with the rapid growth of the Korean economy these days. This increase of the sea-borne cargoes has made the Korean coastal traffic so congested that this can be a cause of large pollution as well as great marine casualties such as loss of human lives and properties. Marine casualties generally result from the complicated interaction of natural and human factors; the former being the topographic, marine traffic volume and meteorological conditions, and the latter being the quality of seafares. In this paper, the authors analyse the trend of marine casualties in the Korean coastal and clear up the cause of accidents and examine closely the mutual relations among sea accidents, weather conditions, and marine traffic volume. These accidents are classified into several patterns on hte point of view of ship's size, ship's type and ship's age and its characteristics of each pattern are described in detail. Also, the authors estimate the amount of economical losses resulting from marine casualties which are classified into the accident patterns, and clarify the effects of those losses on B/B(Balance Sheet) and P/L(Profit & Loss) of Korean shipping companies and Korean national economy. The analyzed results of marine casualties are summarized as follows: 1) The average number of sea accidents is 248 cases per year with the loss of 107 persons during last 13 years. 2) Collision is the top of causes of sea accidents (approx. 36.4%), shipwreck the second (approx. 20.3%), agroung the third rank (approx. 18.2%). 3) The ship's number under 1, 000G/T is approx. 74% of total ship's number of accidents. 4) 80% of total number of marine accidents is taken plact at the coastal waters. (involved ports & narrow channels) 5) Marine casualties are occur likely to in the night, the winter and the summer. 6) The average amount of economical losses is approx. 18.5 billion won. (approx. 0.14% of GNP) 7) Shipwreck is the top of the amount of economical losses (approx. 60.4%), collision the second (aprox. 24.5%), aground the third (approx. 9.9%). 8) The amount of economical losses is approx. 5.24% of gross capital of shipping co., 1.24% of shipping revenue, 1.38% of shipping total income in 1983.

• Journal of Labour Economics
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• v.25 no.3
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• pp.1-34
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• 2002

This paper investigates the effects of hours reduction on growth, investment, and consumption as well as employment. We adopt the basic framework of the indivisibility of labor developed by Hansen (1985) and Rogerson (1988) and extend it by allowing heterogeneity of workers in productive efficiency. On the basis of monthly panel data constructed from Economically Active Population Surveys and Household Income and Expenditure Surveys, we estimate the value of productive efficiency parameter of newly hired workers relative to existing workers by considering differences between the two groups in unobservable as well as observable worker characteristics. Numerical simulation of steady states demonstrates that reduction of statutory weekly hours from 44 to 40 leads to a rise in employees by 4.9 percent. However, GNP, investment, and consumption are all reduced by 2.03 percent, which is attributed to reduction in the amount of effective labor input, which in turn comes from reduction of actual average hours and productivity differences between exiting and newly hired workers.

• Korean Journal of Human Ecology
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• v.20 no.3
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• pp.691-711
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• 2011

This study examines the preliminary license and approval facilitation standards for improvements in quality for childcare centers focusing on the number of children, building space standards, facilities and equipment, and childcare program. Data from 48 caese was collected from childcare centers nationwide in Korea through a questionnaire and building plan. The first step for starting care licensing is to work out the ages and numbers of children within four or five age ranges. The second step is to work out the number of children as small, medium, or large considering staff to child ratios and building size. The Nnext step is to make a choice about childcare service quality classification as minimum, fair, or good, considering space requirements per child for the building, the classroom and the outdoor playground. The next step is to make a choice of space organization relating to service programs, considering the sleeping and eating area, indoor play area, toilet & washing facilities, classroom layouts such as cluster type, double zone type, single zone type, and others. Also, each room and entrance, office, kitchen, storage, laundry, teacher's area, and chilldren's area, need to be checked for space requirements and performances. The last step is to arrange the childcare program with the building and site plan. In conclusion childcare service quality will get better by upgrading of license regulation especially in minimum space requirements per child, corresponding with an increase in GNP and housing area per person. This is needed for childcare licensing in order to determine the quality level of childcare service.