• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.125-134
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• 2021

With the rapid development of the film industry, the number of films is significantly increasing and movie recommendation system can help user to predict the preferences of users based on their past behavior or feedback. This paper proposes a movie recommendation system based on the latent factor model with the adjustment of mean and bias in rating. Singular value decomposition is used to decompose the rating matrix and stochastic gradient descent is used to optimize the parameters for least-square loss function. And root mean square error is used to evaluate the performance of the proposed system. We implement the proposed system with Surprise package. The simulation results shows that root mean square error is 0.671 and the proposed system has good performance compared to other papers.

• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.161-168
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• 2016

In this study, growth enhancing effect of hatchery waste egg decomposed liquid fertilizer in pepper plant cultivation through chlorophyll fluorescence (O-J-I-P) analysis. In a whole growth period, egg decomposed fertilizer treated pepper grew well than non treated plant, though it was not statistically significantly different. Amount of chlorophyll fluorescence of non treated plant was higher thant that of fertilizer treated plant. It is determined that eventually lead to increased photosynthesis. In this study, six parameters, Fo, ABS/RC, RC/ABS, TRo/RC, DI0/RC, and DF Total ABS were the important factors represent efficiency of photochemical responses of pepper plant treated with hatchery waste egg decomposed fertilizer.

• KDI Journal of Economic Policy
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• v.21 no.3_4
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• pp.147-213
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• 1999

본고의 성장회계 분석결과 동아시아의 경이적 경제성장과정에서 자본축적의 중요성이 재확인되었다. 총요소생산성 증가율 측면에서는 동아시아는 선진국과 비슷한 수준이었다. 그러나 개발도상국 지역들과 비교해서 동아시아의 총요소생산성은 훨씬 빨리 증가하였을 뿐 아니라 매우 지속적으로 이루어졌는데, 이 점은 기존 문헌에서 그다지 주목하지 못한 것이었다. 성장회계를 통한 성장요인 분해결과 대외개방도 및 제도의 질 변수가 동아시아와 중남미 및 아프리카 등 다른 개도국 지역의 성장률 차이를 가장 잘 설명하였다. 그러나 동아시아가 선진국보다 빨리 성장한 것은 수렴효과에 기인하였으며, 선진국에 비해 열등한 제도 및 경제정책으로 인하여 동아시아는 이러한 수렴효과조차 충분히 활용하지 못한 것으로 나타났다. 한편 대외개방이 경제성장에 미치는 직접효과뿐 아니라 제도를 개선함으로써 성장에 미치는 간접효과도 고려할 경우 경제성장에서 대외개방도의 양적 중요성은 훨씬 큰 것으로 나타났다. 이러한 결과는 대외개방이 동아시아의 성장에 있어서 가장 중요한 요인이었음을 시사하는 것으로 판단되며, 또한 "대외지향적 무역전략이 추가적인 자유화 조치의 모멘텀을 제공하여 개방의 이익을 추가적으로 실현하는 데 기여한다"는 Krueger(1990)의 주장과 일맥상통하는 것으로 보인다.

• Convergence Security Journal
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• v.16 no.1
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• pp.59-68
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• 2016

Recently, many domestic and foreign industries is increasing gradually in the importance of security such as the emergence of a Convergence Information Technology(internet of things, cloud computing service, big data etc). Among these techniques, the industrial security market is expected to grow gradually and the evolution of security technologies, as well as vulnerabilities are also expected to increase. Therefore, an increase in physical vulnerability factors it is no exaggeration to standards that are determining the security of industrial security. In this paper will be analyzed to the physical security technology and case study, physical vulnerability factor. Thereby this is expected to be utilized as a basis for the countermeasure of physical corresponding infringement and attack in a future.

• Journal of the Korean Data and Information Science Society
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• v.22 no.2
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• pp.255-267
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• 2011

The aim of this study is to utilize system trading for making investment decisions and use technical analysis and Dynamic Time Warping (DTW) to determine similar patterns in the frequency of stock data and ascertain the optimal timing for trade. The study will examine some of the most common patterns in the futures market and use DTW in terms of their frequency (10, 30, 60 minutes, and daily) to discover similar patterns. The recognized similar patterns were verified by executing trade simulation after applying specific strategies to the technical indicators. The most profitable strategies among the set of strategies applied to common patterns were again applied to the similar patterns and the results from DTW pattern recognition were examined. The outcome produced useful information on determining the optimal timing for trade by using DTW pattern recognition through system trading, and by applying distinct strategies depending on data frequency.

• Korean Journal of Labor Studies
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• v.19 no.1
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• pp.1-34
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• 2013

Labor share of income in Korea has fallen from 90% in 1996 to 79% in 2010. This paper explores the factors driving the movements in the labor share of income based on a panel dataset containing 19 years of data on 18 Korean manufacturing industries. The effects of technical progress, globalization and the bargaining power of labor and capital on the labor share of income are tested for the period of 1991-2009. The main empirical results are as follows. (1) Capital-aug menting technical prog ress measured by capital-labor ratio and R&D intensity has a negative effect on the labor share. (2) Market openness measured by the value of export and import as a ratio to value-added production is found to have a positive impact. (3) Globalization of production measured by inward-FDI and outward-FDI as a ratio to total domestic fixed capital is found to have a negative impact on the labor share. (4) Union density is found to have had a statistically significant effect in 1991-1998. This finding is consistent with the efficient bargain model in which firms and workers bargain over both wages and employment. But union density is insignificant in 2000-2009. This implies that since the financial crisis in 1997, the bargaining institution in Korea has been approaching the right-to-manage model in which firms and unions bargain over wages and then firms set employment unilaterally. (5) Variables for domestic financialization measured by dividend-income ratio and financial-fixed assets ratio have an insignificant effect on labor share.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.247-248
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• 2002

CFCs는 가정제품과 공업의 생산과정에서 발포제와 냉매제로 오랜 기간 사용되었다. 1974년, CFCs는 Molina와 Rowland에 의해서 성층권 오존의 고갈 요인으로 인식하게 되었고, 최근에는 지구 온난화의 기여물질로써 사회적 관심이 증가하였다. CFCs의 세계적인 생산은 Montreal 의정서와 그 개정안으로 인해 점차 감소하면서 사용이 폐지되었고, 대체 물질로 HCFCS와 HFCs가 사용되고 있다. 대류권에서 HCFCs와 HFCs는 hydroxyl radicals에 의해 산화되고, 최종 분해산물로 무기산, 염, HF, $CO_2$, HC와 Trifluoroacetic acid(TFA)가 생성된다. (중략)

• Applied Biological Chemistry
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• v.43 no.4
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• pp.291-297
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• 2000

This study was conducted to find out the environmental factors affecting the differences in the half-life of the insecticide cyfluthrin in soil between field and laboratory tests carried out in 1998. Degradation and leaching of cyfluthrin in soil were examined under various environmental conditions that were considered to affect the residuality. Cyfluthrin was degraded 1.9 times faster in non-sterilized soil than in sterilized soil and 1.2 times at $25^{\circ}C$ than at $15^{\circ}C$. The half-lives of cyfluthrin were 61.4 days under the dark condition and 4.5 days under sunlight, and those were 11.8 days under the open condition and 23.8 days under the closed condition. The half-lives of the authentic compound and the commercial product of cyfluthrin were 15 and 1 day in the field test and 26 and 3 days in the laboratory test, respectively. Cyfluthrin was rapidly degraded with an increase in soil moisture content and decomposed faster in the alkaline solution of pH 12 than in the acidic solution of pH 3, but the half-life of cyfluthrin did not make any difference between pH 6.4 of the field test soil and pH 5.6 of the laboratory test soil. Cyfluthrin was immobile in soil from the results that $81{\sim}94%$ of the initial amount remained in the $0{\sim}2\;cm$ layer of the soil column regardless of the amount and time of rainfall after the chemical treatments. From viewing the abovementioned results, soil moisture content, sunlight and formulation type affected greatly soil microbes and volatilization affected slightly, and temperature, pH and rainfall did not affect the big difference in the half-life of cyfluthrin in soil between the field and laboratory tests in the year of 1998.

• The Korean Journal of Applied Statistics
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• v.32 no.4
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• pp.463-483
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• 2019

Since 2000, Korea's total fertility rate (TFR) has been different from that of Japan, Germany, and France where irreversible constants do not change easily in the fertility rate increasing or decreasing phase. It also showed a gradual increase from the minimum fertility level 1.08 in 2005 to 1.23 in 2015, which dropped to 1.17 in 2016, to 1.05 in 2017 and to 0.98 in 2018. This is similar to a double dip in the economic status of a recession. This paper investigates such a TFR increase and decrease factor that predicts the number of births affecting TFR, examines trends in the proportion of married and marital fertility rate broken down by TFR decomposition method. We also examined how these changes affect the change in TFR. According to the results, the number of births is estimated to be between 320 and 330 thousand in 2018, 300 thousand in 2020, 230 and 240 thousand in 2025. The proportion of married is steadily decreasing from 1981 to 2025, and the marital fertility rate is predicted to decline until 2002, then increase from 2003 to 2016 and decrease from 2017 to 2025. Finally, the trend of TFR in terms of number of births, TFR decomposition and statistical model is expected to show 0.98 in 2018, 0.93 to 1.11 in 2020 and 0.76 to 1.08 in 2025.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.291-298
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• 2001

Seawater, sediment and biota in the Kwangyang Bay were analyzed by gas chromatography/quartz furnace atomic absorption spectroscopy (GC-QFAAS) to investigate concentrations and distribution pattern of butyltin compounds (TBT, DBT, MBT) during February, April and July, 1996, Marine biota analyzed were Tapes japcnicus and Crassostrea gigas. The concentrations of tributyltin (TBT) in seawater were in the range of ND-15.7 ng/L for the surface and ND-68.5 ng/L for the bottom. The highest concentration of TBT in seawater was detected in April for the both, surface and bottom water. The maximum value of $TBT_{(bottom)}/TBT_{(surface)}$, 3.6 in April showed the increased input of TBT from the surface water in April compared to February (2.1) and July (0.9). The concentrations of TBT in the sediment were in the range of ND-8.5 ng/g dry wt. The highest concentration of TBT in the sediment was measured in July, This result seems to attributed to the removal of TBT from water column via sorption onto particulate matters to the relatively undisturbed underlying sediment and increased input of TBT by increased fluxes of detritus of marine plankton after spring bloom, in July. The mean values of partitioning coefficient ($K_d$) of TBT between seawater and sediment were $3.0\times10^3$(February), $7.4\times10^3$(April) and $9.4\times10^3$(July). The concentrations of TBT in biosamples were in the range of ND-93.30 ng/g dru wt. (T. japonicus) and ND-138.53 ng/g dry wt. (C. gigas). The seasonal variation of TBT contents in biota was remarkable. The $K_d$ (biological concentration factor) was $7-41\times10^3$ for T. japonicus. and $5-34\times10^3$ for C. gigas. The measured TBT concentrations in seawater in the study area was sufficient to cause the imposex of shellfish and to retard the growth of aquatic organisms including oyster upon chronic exposure.