• Geomechanics and Engineering
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• v.17 no.2
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• pp.133-143
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• 2019

An optimal hydraulic section is critical for irrigated water conservancy in seasonal frozen ground due to a large proportion of water leakage, as investigated by in-situ surveys. This is highly correlated with the frost heave of underlain soils in cold season. This paper firstly derived a practical model for frost heave of clayey soils, with temperature dependent thermal indexes incorporating phase change effect. A model test carried out on clay was used to verify the rationality of the model. A novel approach for optimizing the cross-section of irrigation canals in cold regions was suggested with live updated geometry characterized by three unique geometric constraints including slope of canal, ratio of practical flow section to the optimal and lining thickness. Allowable frost heave deformation and tensile stress in canal lining are utilized as standard in computation iterating with geometry updating while the construction cost per unit length is regarded as the eventual target in optimization. A typical section along the Jinghui irrigation canal was selected to be optimized with the above requirements satisfied. Results prove that the optimized hydraulic section exhibits smaller frost heave deformation, lower tensile stress and lower construction cost.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.4
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• pp.586-595
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• 1996

급변하는 국내외의 교역환경 변화에 따라 의류산업에도 새로운 경영 전략 수립이 요구되고 있다. Quick Response(QR)는 의류제품을 생산하는 기업의 경쟁력을 증가시키기 위해 소개된 새로운 경영 전략으로서, 유통 채녈 사이에 정보와 상품의 흐름을 효울화시켜 최대의 소비자 만족을 제공한다. 본 연구의 목적은 QR technologies의 사용현황을 밝히고 기업 특성과 QR technologies 사용수준과의 관계를 조사하였다. 종족변수는 QR technologies의 사용 수준이며, 선별된 독립변수들은 기업크기 (firm size), 기업전략 (organizational strategy), 제품종류(product category) , 패션변화(fashion change), 주기 적변화(seasonal change)였다. 조사대상은 미국 전역에서 무작위로 추출된 306개의 의류업체를 대상으로 하였으며, 1차 우편과 2차 전화로, 설문지를 통해 자료수집을 하였다. 설문 응답률은 47%(n=103)였고, 자료의 분석은 기술통계(i, e., 빈도, 퍼센트)와 비모수통계기법을 사용하였다. 가장 많이 사용되고 있는 QR technologies는 소량주문(small lot orders) , 단기 사이클 재단 계획 (short cycle cut planning)과 고객의 견이 반영 된 생산계획 (Production planning with customers)이였다. 가장 적게 사용되고 있는 QR technologies는 전자 재주문(electronic reorder)과 단위 생산 시스템 (unit production system)이 였다. QR technologies 사용수준에 관계가 있는 것은 기업크기 (firm size), 기업전략 (organizational strategy), 패션변화(fashion change) 임으로 나타났다. 의류업체의 크기가 클수록, 혁신적 선도기업 일수록, 패션변화가 큰 제품을 취급할수록 QR technologies의 사용수준이 높은 것으로 나타났다. 의류업체는 자원과 생산하는 제품종류에 따라 경영전략과 QR technologies의 사용수준이 다양하였다.

• Journal of Korean Elementary Science Education
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• v.35 no.1
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• pp.39-53
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• 2016

This study aimed to understand students' learning in elementary science classes in terms of participatory perspective. Participatory perspective is based on the participationist views on learning. Based on the participatory perspective, this study used two concepts of participationism: 'the changes of learning on commognition' of Sfard (2007) and 'the identity' of Wenger (1998/2007). Based on these concepts, four episodes of an elementary science class were analyzed. The results showed that students carried out their learning from objective-level learning to meta-level learning. And students defined who they are by identifying and negotiating scientific meaning during the learning. These results showed students become members of science community through their participations in science class.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.27 no.2
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• pp.49-70
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• 2022

Sea Surface Temperature (SST), one of the ocean features, has a significant impact on climate, marine ecosystem and human activities. Therefore, SST prediction has been always an important issue. Recently, deep learning has drawn much attentions, since it can predict SST by training past SST patterns. Compared to the numerical simulations, deep learning model is highly efficient, since it can estimate nonlinear relationships between input data. With the recent development of Graphics Processing Unit (GPU) in computer, large amounts of data can be calculated repeatedly and rapidly. In this study, Short-term SST will be predicted through Convolutional Neural Network (CNN)-based U-Net that can handle spatiotemporal data concurrently and overcome the drawbacks of previously existing deep learning-based models. The SST prediction performance depends on the seasonal and interannual SST variabilities around the southern coast of Korea. The predicted SST has a wide range of variance during spring and summer, while it has small range of variance during fall and winter. A wide range of variance also has a significant correlation with the change of the Pacific Decadal Oscillation (PDO) index. These results are found to be affected by the intensity of the seasonal and PDO-related interannual SST fronts and their intensity variations along the southern Korean seas. This study implies that the SST prediction performance using the developed deep learning model can be significantly varied by seasonal and interannual variabilities in SST.

• Journal of Korea Water Resources Association
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• v.31 no.2
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• pp.155-165
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• 1998

As an improvement on qualities of lives and a change in the habitual ways people eat require more water to be used for daily lives, the amount of wastewater generated from our usual lives is also expected to be in higher rate of consumption. The unit loading factor of sewage flow-rate based upon the number of people living in the apartment complexes has to be found for the design of the sewage or wastewater treatment facilities. These data are definitely thought to be useful for the plans to operate the sewage treatment facilities and for those to establish the plans toward a management of water qualities. Thus this study has shown that the data regarding the water supplies and the number of apartment residents within the 123 districts of KNHC(Korea National Housing Corporation) were collected and analyzed. One district in Seoul and the other local district were chosen an the experimental sites for th hourly, daily, weekly and seasonal measurements of the influent sewage flow-rate. The unit loading factor of influent sewage flow-rate were determined through the comparison of total sewage amount in combination with the number of people residing in two apartment complexes with supplying amount of water.

• Journal of Navigation and Port Research
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• v.30 no.4
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• pp.309-314
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• 2006

Community structure and biodiversity of benthic marine algae were studied in the rocky shore of Phohang New Port, Yeoungil Bay. A total of 79 species of marine algae including 8 Chlorophyta, 23 Phaeophyta and 48 Rhodophyta are listed. The dominant algal species were Corallina pilulifera in all seasons, and Sargassum homeri in winter. Lomentaria catenata, Lomentaria hakodatensis, Grateloupia laceolata, Sargassum thunbergii, Chondria crassicaulis, Ulva pertusa, and Hypnea charoides were subdominant at different seasons. The algal biomass per unit area of the benthic algal community in Pohang New Port under construction was 14506 - 398.93 g dry wt m-2, which means that its annually averaged value is 273.45 g dry wt m-2 . The seasonal change in algal biomass showed highs in winter and spring, and lows in summer and autumn. The algal species diversity (H') based on algal biomass was 2.07 annually in average, with 2.42 in winter, 2.65 in spring, 1.79 in summer and 1.43 in autumn. It was high in winter and spring seasons and low in summer and autumn seasons. It is caused by that spring and winter are the profitable growth time for algae and species components in this study were dominated by the annual or seasonal rather than perennial plants.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.3
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• pp.175-184
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• 2012

Changes of fish assemblage inhabiting around Dae Island in Gwangyang Bay, Korea were investigated using a small beam trawl monthly from March 2009 to February 2010. These data were compared with those obtained in previous studies(1990~1991 and 1995~1996) at our study sites. A total of 8,133 fish belonging to 74 species in 38 families were collected. Leiognathus nuchalis, Argyrosomus argentatus, Acentrogobius pellidebilis, Sillago japonica, Apogon lineatus, Thryssa hamiltoni, Repomucenus richardsonii, Pholis nebulosa, Pleuronichthys cornutus, Hexagrammos otakii, and Limanda yokohamae dominated, and these were responsible for 89.5% and 58.9% in the number of individuals and in biomass, respectively. These were primarily small species or early juveniles of larger species. Seasonal variation in both species composition and abundance was large: the peak number of fish species occurred in May and October 2009, whilst both number of individuals and biomass were the highest in May 2009. Fish numbers as well as biomass was lowest in January and February 2010. Seasonal changes in the abundance of fishes corresponded with temperature. Compared with the previous studies, the total number of individuals and biomass per unit area($m^2$) were higher, and the predominance of L. nuchalis occurred while abundances of Liparis tanakai were significant decreased. These results seemed to be change of species composition in fish assemblage which was due to variation of annual environmental characteristics in Gwangyang Bay.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.3
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• pp.115-132
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• 1996

The present problems concerning the control of generation, storage, collection, transfer and transport, processing and disposal of the municipal waste are serious. And the transportation of the municipal waste is recently a important part of solid waste treatment and disposal. The waste pneumatic transportation system is expected to be an effective method for use in solving that problems. In this study, pneumatic transportation system was applied to 2,000-5,000 households of public/group housing for economic and technical analysis on the basis of data for working and operation. The proper equipment must be selected through economic and technical analysis for generation and properties of waste because the equipment in facilities of system is various. And the efficient operation method should be studied on the basis of information on the record of oeration. As the wet food waste clogs the pipeline, it is necessary to examine under the actual condition. The maximum unit waste generation rate based on the assumption that each household is comprised of 3.20 people is determined $2,340g/household{\cdot}day$, and it is included the 50% increase of seasonal and daily change.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.2
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• pp.87-96
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• 2016

The ionospheric error, which is one of many error elements considered during the Global Navigation Satellite System (GNSS) positioning, is hard to be predicted due to the influence of geomagnetic activity and irregular solar activities. Thus, the present study analyzed a change pattern in the ionosphere through Global Ionosphere Map (GIM) data for 12 years from 2003 to 2014 and a variation in the Slant Total Electron Content (STEC) between Sinuiju and Busan which was the longest range in the southeastern direction of the Korean Peninsula. The variation in the STEC verified the diurnal, annual, and solar cycle variations due to the influence of solar activity. The diurnal variation was characterized that the variation in the STEC started to increase from 6-7 am and reached the maximum at 13-14 pm followed by being decreased. The seasonal variation was characterized that the variation in the STEC was high in spring and autumn whereas it was low in summer and winter. The solar cycle variation revealed that the variation in the STEC increased during solar maximum and decreased during solar minimum. The variation in the STEC was up to 20 Total Electron Content Unit (TECU) during the solar minimum and up to 60 TECU during solar maximum.

• Journal of Nutrition and Health
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• v.55 no.2
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• pp.201-210
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• 2022

Vitamin A (Vit A) is a lipid-soluble vitamin required for diverse normal body functions, including good vision, reproduction, growth, development, and cellular differentiation. The therapeutic effects of Vit A have been demonstrated for the treatments of inflammation, low immunity, and cancer. The present review discusses the scientific evidence for establishing the 2020 Dietary Reference Intakes for Koreans (KDRI) for Vit A, issues caused by unit change of Vit A, and suggestions for the 2025 KDRI revision. Due to the changes in the standard bodyweight observed in several age groups, the 2020 KDRI had minor revisions as compared to the 2015 KDRI. In the 2015 KDRI, the Vit A unit has changed from retinol equivalent (RE) to retinol activity equivalent (RAE) and the activity of carotenoids became half with RAE compared to RE due to this unit change. Since the Vit A intake of Koreans relies heavily on plant-based carotenoids, the dietary intake of Vit A in Koreans as determined by considering the RAE was much lower than values obtained with RE. The analysis for Vit A intake by the Korean National Health and Nutrition Survey only reflects intakes of retinol and beta-carotene. Thus, it would be necessary to include the consumption of other provitamin A, such as alpha-carotene and beta-cryptoxanthin. Moreover, assessing the amounts of Vit A in foods should be customized to Korean diets since there are seasonal variations in the carotenoid concentration of plants. Moreover, other factors such as age- and sex-specific intake data and considerations of baseline micronutrient status, body mass index, and dietary patterns should be considered for developing more precise KDRI. In particular, the Vit A requirement needs to be met by consuming diverse foods, including animal foods.