• Ocean and Polar Research
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• v.27 no.4
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• pp.477-490
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• 2005

The development of manganese nodule mining technology is very important in order to secure a long-term and stable supply of rare strategic metals. In the twenty years following the R&D activities with the international consortia in the 1970s, studies on mining technologies have been carried out by several national projects in Korea. The current metal prices such as copper, nickel, cobalt, and manganese have been drastically changed since 2002. Rapid economic growth of Asian countries, especially China, have induced the situation. And the possibility of copper shortage is looming just around the comer. Because of the imbalance between production and consumption, copper is fundamentally the most threatened metal in the future in terms of potential metal shortage. Manganese nodules contain a considerable percentage of copper as the future metal resource. Therefore, it is necessary to concentrate our effects on developing these resources. This paper introduces our evaluation of R&D progress for the development of manganese nodules. The issue and role of manganese nodules during the difficult period of a potential future metal shortage period is discussed and its prospect outlined. Also, this paper tried to emphasize the necessity of continuous R&D efforts for the commercial development of such mineral resources.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.885-901
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• 2020

A forest watershed management project was introduced in 2004 to develop ecologically sound forest watersheds. It includes landslide prevention and erosion control, water resource management, landscape development, and forest resource management. However, it has been managed fragmentarily and inefficiently, far from the original intents. This study investigated current status, problems, and improvement measures of the project. Literature reviews were conducted on forest watershed management in Korea and other countries, and surveys were conducted on 201 erosion control experts. When introduced, the forest watershed management project was well planned and implemented as intended. It later turned to focus only on disaster prevention such as erosion control dams and stream conservation measures. The survey results showed that a majority (89% and 86%) of surveyees wanted increases in the project period and budget. They also responded that conflicts with local residents (51%) and determining project locations (32%) were the most difficult tasks when implementing the projects, and only 36% kept project records. To plan and implement the projects as intended, the following suggestions should be considered: (1) establishment of a solid legal foundation and improvement of the erosion control practices law; (2) increase in the project period (from 1 to 2 - 3 years) and budget; (3) development of a manual for project site selection and guidelines; (4) monitoring and systematic information management; and (5) development of spatial analysis tools for watershed analysis and management.

• Journal of Life Science
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• v.10 no.1
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• pp.1-6
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• 2000

Larval development, adult longevity and oviposition of the beet armyworm, Spodoptera exigua H bner was studied at 16, 20, 25 and 3$0^{\circ}C$ with a 16L: 8D photoperiod. Egg hatchability of S. exigua was the highest at 3$0^{\circ}C$ and reduced with decreasing temperature. Egg period was the shortest at 3$0^{\circ}C$ and prolonged with decreasing temperature. Percent pupation was became higher at higher temperature form 23.2% to 94.0%. Developmental period of larva was the shortest at 3$0^{\circ}C$, but extended with decreasing temperature. Adult emergence ratio was the highest at 3$0^{\circ}C$ and reduced with decreasing temperature. The mean pupal period was 35.2, 14.4, 7.8 and 5.0 days at 16, 20, 25 and 3$0^{\circ}C$, respectively. Relationships between constant temperature and the developmental velocity of egg, larva and pupa were linear. Developmental threshold temperature seems to be 13.3 8$^{\circ}C$ for egg, 14.02$^{\circ}C$ for larva, 14.09$^{\circ}C$ for pupa, and 13.84$^{\circ}C$ for egg the adult. Estimated value of the total effective temperature for completing each stage was 36.89 day-degree for egg, 155.72 day-degree for larva, 79.20 day-degree for pupa, and 273.41 day-degree for egg to adult. Female longevity varied to temperature from 11.4 days at 16$^{\circ}C$ to 5.8 days at 3$0^{\circ}C$, and male longevity was longer than that of female. Preoviposition period was the shortest at 3$0^{\circ}C$, but prolonged with decreasing temperature. It was about 2.7 times longer at 16$^{\circ}C$ than that at 3$0^{\circ}C$. Number of eggs per female was the highest at $25^{\circ}C$, followed by 20, 30 and 16$^{\circ}C$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.42-43
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• 2018

The research is to suggest the compensating strength values depending on various managing periods of concrete based on the strength development model calculated with equivalent age method for 20% of blast furnace slag replaced concrete. As a result, for 28 days of managing period, 9, 6, and 3MPa of compensating strength values were suggested when the temperatures were from 4 to 6℃, from 6 to 12℃, from 12 to 17℃, respectively. Additionally, for 42 days of managing period, 6 and 3MPa of compensating strength value was suggested when the temperature was from 4 to 7℃, from 7 to 12℃, and for 56 days of managing period, 3MPa of compensating strength value was suggested when the temperature was from 4 to 9℃. Furthermore, for 28, 42, 56, and 91 days of managing periods, any compensating strength values were needed when the temperature were higher than 17, 12, 9, and 4℃, respectively.

• Journal of Korean Academy of Nursing
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• v.1 no.1
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• pp.77-84
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• 1970

A survey was conducted on 2,321 Chung Rhang Middle School boys to check out their physical growth, development and the number of parasite carriers during the period from June 16. to June 23. 1970 As the results of this study, the following conclusions were revealed. A) Physical Growth and Development State. 1. Direct curve in physical growth and development was observed during the period from 13 to 16 years of age. 2. The age and quantity of maximum growth and development. Height; 13~14 years of age 6.1cm Body weight; 14~15 years of age 5.1kg Chest circumference; 13~14 years of age 9.9cm Sitting height; 14~15 years of age 3.4cm 3. Comparison with Japanese students Most Korean students are shorter than Japanese students, though the standard of height became higher than before. The standard of body weight is visibly lower than Japanese students. The standard of chest circumference of the students of age 14 is higher than counter part of Japanese students and the all boys are lower than Japanese students except at the age of 14. The standard of the sitting heights of the Korean students are growing steadily, but every students are shorter than Japanese students. 4. The greatest differences in physical growth and development were shown in 13~14 years of age. 5. The students of 13~15 years of age developed their bodies most highly according to index of Rohrer. 6. Body weight and chest circumference have not grown enough compared with height. The development of sitting height was made highly and the development is steadily growing as they grow old. B. The Number of Parasite Carriers The number of parasite carriers was shown 79.4 per cent among all the student checked out. The number of trichuris was shown 79.7 per cent. The number of parasite carriers was shown higher per cent as the grow old.

• Archives of design research
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• v.17 no.4
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• pp.129-140
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• 2004

The process of game development is contained of many steps that is hard to forecast success or failure. In order to develop successful game, the development period should be shorter, which could reduce development cost. In order to reduce development period and cost, it is needed to make a communication among planners, programmers, graphic designers and investors lively with a prototype as a communication tool. In this study, the concrete examples are demonstrated how to use prototypes as a tool for communication and feedback of team members, in the process of game development. This paper explains the characteristics of various types of prototypes according to types of game contents. This paper demonstrated two types of prototype according to development stage, one type is a prototype to gather feedback in the planning stage, the other is a prototype to make team members cooperate and communicate in the stage of production stage.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.2
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• pp.189-197
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• 2006

Twenty small-scale farms of two villages (A and B) were surveyed to identify the feeding traits, milk productivity and nutritional status of lactating cattle and buffalo in Terai, Nepal. Constituents and dry matter (DM) of feed supplied, body condition score (BCS), heart girth (HG), bodyweight (BW), milk yield (MY) and plasma metabolites were obtained in the pasture-sufficient, pasture-decreasing and fodder-shortage periods. Milk yield of 305-day lactation was estimated by the daily MY. The supplies of rice straw and native grass were lower and higher in the pasture-sufficient period than in the other periods, respectively (5.5 kg/day vs. 9.8 kg/day and 3.2 kg/day vs. 0.4 kg/day, respectively, p<0.01). The roughage-supplement rates of the animals were higher in village A than in village B (5.0 vs. 2.2 in cattle and 9.3 vs. 1.8 in buffalo, p<0.01). The variance of feed constituents among the periods and between the villages induced different supplies of CP, NDF and TDN. The concentrations of CP and TDN in the cattle feed were higher in the pasture-sufficient period than in the other periods (9.1% vs. 7.3% and 57.4% vs. 51.0%, respectively, p<0.01). The supplies of CP for cattle and buffalo, and of TDN for buffalo were lower in village A than in village B (7.5% vs. 8.7% and 6.6% vs. 9.1% [p<0.01], and 53.1% vs. 56.2% [p<0.05], respectively). The BCS, HG and BW of the animals were lower in village A than in village B (2.51 vs. 2.86, 156 cm vs. 170 cm and 300 kg vs. 318 kg, respectively in cattle, 2.83 vs. 4.00, 186 cm vs. 216 cm and 429 kg vs. 531 kg, respectively in buffalo, p<0.01). The cattle yielded more milk in the pasture-sufficient period than in the other periods (7.9 liters/day vs. 6.6 liters/day, p<0.01). The 305-day MY of cattle that calved in the fodder-shortage period was lower than that of cattle that calved in the other periods (1,900 liters vs. 2,251 liters, p<0.01). The MYs of cattle and buffalo were lower in village A than in village B (6.2 liters/day vs. 8.1 liters/day and 3.7 liters/day vs. 7.7 liters/day, respectively, p<0.01). The 305-day MY of cattle was lower in village A than in village B (1,935 liters vs. 2,409 liters, p<0.01). The concentrations of plasma albumin and urea nitrogen in cattle were lower in village A than in village B (3.2 g/dl vs. 3.4 g/dl [p<0.01] and 7.4 mg/dl vs. 10.2 mg/dl [p<0.05], respectively). The different supplies of CP, NDF and TDN among the periods and between the villages might have affected MY and nutritional status in cattle and buffalo. It was likely that the lower supplies of CP and TDN for cattle that calved in the fodder-shortage period and in village A lowered the 305-day MY of cattle.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.4
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• pp.161-168
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• 2009

The most generalized form of the triadic operating policy for an M/G/1 queueing model is developed. It consists of three simple N, T and D operating policies and has a peculiar structure possessing concepts of dyadic policies. Using the concept of the pseudo probability density function of the busy period, its expected busy period for the controllable M/G/1 queueing model is derived. Since the obtained result is the most generalized form the triadic polity, the expected busy periods for all known dyadic policies are recovered as special cases from it.

• Environmental Analysis Health and Toxicology
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• v.25 no.4
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• pp.279-286
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• 2010

Objectives : Platinum nanoparticles (PNPs) are potentially useful for sensing, catalysis, and other applications in the biological and medical sciences. However, little is known about PNP toxicity. In this study, adverse effects of PNPs on the postnatal development of mouse pubs were investigated. Methods : PNPs (size: 20 nm) were prepared and orally administered to mice during premating, gestation, and lactation periods (0.25 mg/kg, 0.5 mg/kg, and 1 mg/kg). Maternal and pup toxicity were evaluated. Results : PNPs did not affect blood biochemical parameters or mortality in dams during the experimental period. Histopathological signs were not observed and pup number was not different between the control and treated groups. Deformity and stillbirth were not observed in the pups. However, PNPs increased pup mortality and decreased the infant growth rate during the lactation period. Conclusion : PNPs may have adverse effects to the postnatal development of mouse pups.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2005.10a
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• pp.139-142
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• 2005

The design of the period after 20th century has rapid change. It is due to the improvement and the change of technology which is composed of the parameter that is the science and the machine after the Industrial Revolution. The technology becomes the criteria of the value and appears to the symbol of the period. The purpose of this study is to define the expression characteristics by the development of technology and to examine how specificly it makes the influence on the change of Interior expression characteristics. Interior design can be expressed more creative and 4th dimensional spaces by the development of technology from the space, form and material side