• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2011.11a
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• pp.16-18
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• 2011

Evaluation of climate change on the rice productivity was conducted using crop growth simulation model, where Odae, Hwaseong, Ilpum were used as a representative cultivar of early, medium, and medium-late rice maturity type, respectively, and climate change scenario 'A1B' was applied to weather data for future climate change at 57sites. When cropping season was fixed, rice yield decreased by 4~35% as climate change which was caused by poor filled grain ratio with high temperature and low irradiation during grain-filling. When cropping season was changed, rice yield decreased by only 0~5% as climate change which was caused poor filled grain ratio with low irradiation during grain-filling period. However, this irradiation decline was less than when cropping season was fixed. Therefore, we need to develop rice cultivars resistant to low irradiation which can maintain high filled grain ratio under poor irradiation condition, and late maturity rice cultivars whose growing period is longer than the present medium-late maturity type.

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.4
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• pp.331-338
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• 1994

The objective of this study is to obtain the basic data for investigating the potentiality of continuous utilization (first cutting in the late fall and regrowth yield in next spring) of forage rape seeded in fall. Non-structural carbohydrates(NSC) in leaves and roots of forage rape seeded on Oct. 3 were analyzed during a growth period. The greatest change in NSC content was observed between the wintering and the early spring period. The total content of soluble sugar in leaves and roots highly increased from the late fall(Nov. 7) to the wintering period (Feb. 4), and then rapidly decreased on the early regrow^ period(Mar. 31). The contents of fructose and glucose were relatively lower, and their quantitative change also was smaller than those of other sugars through entire growth period. The highest accumulation of sucrose occured hum the late fall to wintering period, and then greatly decreased in the early regrowth period. Sucrose content in roots was 2.3 times higher than that of leaves in wintering period. Starch was the largest pool of NSC and its content in leaves and roots showed a similar pattern with that of sucrose through entire growth period. Starch contents in leaves and roots were 38mg and 189mgl gDM in the late fall(Nov. 7), 187 and 497mg/gDM(Feb. 4) in the wintering period and 69 and 79mglgDM(Mar. 28) in the early regrowth period, respectively. The results clearly showed that the main reserve forms of NSC are starch and sucrose, and that they are hlghly stored in roots in overwintering forage rape.

• Communications of Mathematical Education
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• v.20 no.2 s.26
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• pp.207-214
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• 2006

Mathematics can be divided into practical mathematics and logical mathematics. The 'Enlightenment Period' is the period in which our mathematics shifted from practical mathematics to logical mathematics. Considering the change of our school mathematics and mathematics education in the enlightenment period, we reach the following conclusions. First, the contents and forms of mathematics books followed to Western style, but the attitudes adhered to on. Second, making much of results than process, we are afraid of proof. Third, we necessitate the mathematics culture of enjoying itself.

• Journal of the Korean Solar Energy Society
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• v.29 no.6
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• pp.56-61
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• 2009

The effects of design parameters for small scale hydro power(SSHP) plants due to climate change have been studied. The model to predict hydrologic performance for SSHP plants is used in this study. The results from analysis far rainfall conditions based on KIER model show that the capacity and load factor of SSHP site had large difference between the period. Especially, the hydrologic performance of SSHP site due to rainfall condition of recent period varied in design flowrate sensitively. However climate change gave small effect in load factor of existing SSHP plant. And also, the methodology represented in this study can be used to decide the primary design specifications of SSHP sites.

• Korean Journal of Organic Agriculture
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• v.22 no.2
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• pp.335-345
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• 2014

The productivity decrease in environment-friendly farming is the biggest obstacle for the development of environment-friendly food market. This paper aimed to analyze the productivity change in environment-friendly farming of fruit vegetables (oriental melon, watermelon, and strawberry). Box-Cox transformation model was used to infer the functional form of productivity change. The results showed that the periods of productivity restoration to 90% level in oriental melon, strawberry, and watermelon were 14.1 years, 11.4 years, and 6.0 years, respectively. The forms of productivity restoration of fruit vegetables showed differences due to their growth characteristics, incidences of crop pests, preference for the environment- friendly agricultural products, cultivation period and so on. Because the form and period of productivity restoration were different depending on kinds of fruit vegetable, the government policy should be established considering this point of view.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.39-47
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• 2011

The aim of the study is to predict potential evapotranspiration and crop water requirement using meteorological data from MIROC3.2 with A1B scenario. Increase of evapotranspiration due to temperature rise can be observed out of the analysis, while effective rainfall decreased. The evapotranspiration elevation results in large amount of crop water requirement in the paddy farming. It can be seen that rainfall intensification at non-irrigation period brings effective rainfall decrease, while contributes to higher demand of crop water at irrigation period. It is necessary to secure additional water resources to adapt the climate change. It is expected that estimation on potentialevapotranspiration in this study can be used for formulation of master plan of water resources.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.4
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• pp.507-517
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• 1995

The failure rate of an item depends on operational environment. When an item has a chance failure period and a wearout failure period in sequel, the severity of operational environment causes the increase in the slop of wearout failure rate or the increase in the magnitude of chance failure rate. For such a change of operational environment, this paper concerns the change of optimal preventive replacement time. Two preventive replacement policies, age replacement policy and periodic replacement policy with minimal repair, are considered. Investigated properties are: (a) in age replacement policy, optimal preventive replacement time increases as the chance failure rate increases and optimal preventive replacement time decreases as the slope of wearout failure rate increases, and (b) in periodic replacement policy with minimal repair, optimal preventive replacement time increases as the slope of wearout failure rate increases; however, the change of chance failure rate does not alter the optimal preventive replacement time.

• Computers and Concrete
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• v.33 no.5
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• pp.559-572
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• 2024

Problems of under-sized dams (small dams with large basin area) could get worse under the global warming condition. This study evaluates the possible change of these problems with the Namgang Dam, an under-sized dam in Korea. For this purpose, first, this study simulates the dam inflow data using a rainfall-runoff model, which are then used as input for the reservoir operation. As a result, daily dam storage, dam release, and dam water supply are derived and compared for both past observed period (1973~2022) and future simulated period (2006~2099) based on the global warming scenarios. Summarizing the results are as follows. First, the inflow rate in the future is expected to be increased significantly. The maximum inflow could be twice of that observed in the past. As a result, it is also expected that the frequency of the water level reaching the high level is increasing. Also, the amount and frequency of dam release are to be increased in the future period. More seriously, this increase is expected to be concentrated on rather extreme cases with large dam release volume. Simply, the condition for flood protection in the downstream of the Namgang Dam is becoming worse and worse. Ironically, the severity of water shortage problem is also expected to become much worse. As the most extreme case, the frequency of no water supply was zero in the observed period, but in the future period, it becomes once every five years. Both the maximum consecutive shortage days and the total shortage volume are expected to become more than twice in the future period. To prevent or mitigate this coming problem of an under-sized dam, the only countermeasure at this moment seems to be its redevelopment. Simply a bigger dam with larger dam reservoir can handle this adverse effect more easily.

• Korean Journal of Organic Agriculture
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• v.31 no.1
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• pp.63-77
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• 2023

The purpose of this study is to help operate and manage the new food period, use-by-date by investigating consumer perception of various food periods, and change of purchasing and consumption period by food period label. Compared to the purchasing period of sell-by-date, the ratio of the purchasing period also increased as the proposed period of the use-by-date and the best before date increased. The use-by-date should be set at least 15 days to reduce food waste as the consumption period is the same as the sell-by-date. This can be said to have an anchoring effect that changes the purchasing and consumption period of consumers depending on how much the food period is indicated even for the same product. In order to reduce consumer confusion and food waste due to sell-by-date, it is considered to label the sell-by-date and use-by-date or use-by-date and best before date in parallel.

• Journal of Nutrition and Health
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• v.40 no.1
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• pp.69-77
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• 2007

The study was conducted to investigate the factors associated with bone mineral content (BMC) changes among early pubertal aged girls. Two hundred and thirty girls between 9 to 11 years of age participated in (our surveys over 2 year period. During each survey, dietary intakes were collected with 3-day food records, BMC of left leg's calcaneus were measured by PIXI (Lunar Ltd.) and body composition was measured by bioimpedance method (Inbody 3.0 Biospace Co. Ltd, Seoul, Korea). Mean values of BMC increased in consecutive measurements -1.48 g, 1.54 g, 1.61 g and 1.66 g. The change of BMC between the first and last measurements was significantly positively correlated with % body fat, negatively correlated with BMC at the baseline (p < 0.05). Change of BMC was also significantly positively correlated with % change of lean mass and mineral mass between the first and last measurements. Nutrient intakes during the study period were calculated as mean daily intakes from all surveys. Mean daily intakes of Vit. C and Vit. $B_6$ were positively and isoflavone intake was negatively correlated with changes of BMC (p < 0.05). In stepwise regression of BMC change with body composition and nutrient intakes, baseline values of BMC, weight, BMI and age, % change of mineral mass during the study period, mean intakes of isoflavone, Vit. $B_6$, protein, carotene and zinc were significant explanatory variables ($R^2=0.38$, p <.001, F = 32.39). The results imply that the change of BMC among early pubertal aged girls are associated with some body composition and intakes of certain nutrients.