• Journal of Bio-Environment Control
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• v.14 no.3
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• pp.212-217
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• 2005

This experiment was conducted to investigate the effect of water soluble fertilizer(WSF) and slow release fertilizer(SRF) on the growth of carnation(Dianthus caryophyllus 'Invitation') cultured in C-channel mat irrigation system. Plants grown in $0.8{\~}1.0\;g{\cdot}L^{-1}$ of WSF showed the highest quality, especially on fresh and dry weight of aerial part, leaf number, total leaf area, plant height, and branch number. All plants showed increase of growth rate around 60 days after treatment, although there was a different increase rate. Total leaf area decreased its increase rate after 90 days after treatment. Carnations supplied by WSF showed better growth and quality than SRF, and the optimum concentration range of WSF for pot-carnation was $0.8{\~}1.0\;g{\cdot}L^{-1}$ in C-channel mat irrigation system.

• Communications for Statistical Applications and Methods
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• v.18 no.6
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• pp.687-696
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• 2011

Customer Lifetime or Customer Lifetime Value is a essential metric of differentiated CRM marketing and differentiated marketing strategy as a company core competency. However, customer lifetime used in companies is easily obtained from a confined simple customer attrition rate at some specific time point regardless of customer characteristics. In this study, in order to overcome the constraints of previous simple methods and to make practical use of it in industries, we suggest a method that estimates a customer lifetime using a customer segment based survival analysis with the censored data of customers; in addition, we apply this method to A mobile telecom company data. A method using customer segment based survival analysis is suggested in this study 1) includes all customers having different subscription dates, 2) reduces individual error, 3) can reflect trends after the observed time point and is more realistic.

• Journal of the Korean Wood Science and Technology
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• v.48 no.4
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• pp.417-430
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• 2020

The flame retardancy, such as carbonized length and area, of four plank type wood products by the spreading concentration and impregnation time of flame retardant were measured according to standard of the Nation Fire Agency in Republic of Korea. To measure the flame retardancy, Korean pine plywood, Japanese larch plywood, Japanese cypress planks, and perforated birch plywood boards were treated with self-development flame retardant by 300 and 500 g/㎡ spreading concentration and those were compared with control specimen. In general, the flame retardant performance of wood products improved as the spreading concentration of flame retardant increased. Except for Japanese larch plywood, there was no significant difference in the flame retardant performance by the spreading concentration. The flame retardant performance of perforated birch plywood board was positively correlated up to 60 minutes of impregnation time, but then gradually decreased. These results about the flame retardancy of wood products by spreading concentration and impregnation time were expected to be basic data for improving flame-retardant treated wood.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.935-938
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• 2005

In this paper, we present the importance of an information communication and weather information system. And after we look into technology on a weather information system setup which does the ubiquitous to the foundation, we deduce an all sorts key point technology for the implementation of a weather information system and the time come true based on it, and we find the practical use plan of a weather information system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.1
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• pp.93-104
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• 2011

A conditional access system is an essential element in IPTV services enabling service providers to allow authorized access to their services only to paid subscribers. Currently, there are two types of IPTV service models, namely PPC (pay-per-channel) and PPV (pay-per-view). However, a more desirable model would be the flexible PPC model, in which subscribers are free to choose any combination of preferred channels and add/remove channels independently. In this paper, we first point out that a previously proposed key management scheme for F-PPC is not secure. We then propose a new conditional access system using 4-level key hierarchy to realize secure F-PPC services. Compared to existing schemes, the proposed system is very efficient, just requiring O(1) communication for key update.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.107-116
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• 1999

To study the characters of surface sediment and to describe the seasonal depositional environment as a result of sedimentation process off Byun-San Peninsula, a total 61 samples of surface sediment (32 samples in summer; 29 samples in winter) were collected and analysed. A digitized depth data from sea chart and echosounding profiles along five trans-sections were helpful for understanding the morphological factors. The types classified by the characters of surface sediment are type I (sand, S), type II (silty sand, zS), and type ill (sandy silt, sZ). Mean grain size varies from 2.11 to 7.81 ${\Phi}$. The positive-skewness shows the typical tide-dominated environment. The sediment type of the northwestern stations is medium sand and the sorting value is 0.5~1.4 ${\Phi}$ of well/moderately sorted. Meanwhile, other stations are composed of muddy sands and sandy muds transported from rivers and offshore. These sediment types toward inshore change gradually from silty sand to sandy silt. According to the C/M diagram, there are three major transport modes of sediment: bed load (Mode A), graded suspension (Mode B), and suspension (Mode C), correlating with north-eastern sandy area, middle part of silty-sand area, and southern sandy-silt area, respectively. The result of Principal Component Analysis shows also similar pattern of sediment types. In result, sediment texture of type III tends to be finer and more poorly-sorted than that of type II and sediment facies are correlateed with sedimentation process.

• Korea Trade Review
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• v.43 no.4
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• pp.155-175
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• 2018

This study estimates the technical efficiency and total factor productivity(TFP) of and analyzes the relationship between TFP and exports for Korean manufacturing companies from 2000 to 2016. Specially, TFP is decomposed into Technical Change(TC), Technical Efficiency Change (TEC), and Sale Effect(SE), and compared between large and small enterprises. First, in the case of technical efficiency, the Korean economy has been very vulnerable to external shocks, such as the sharp decline following the 2008 financial crisis. The efficiency of the electronics, automobile, and machinery sectors is low and needs to be improved. In addition, the technological efficiency of large enterprises is higher than that of SMEs in most manufacturing sub-sectors except for non-ferrous metals. In the case of TFP, most changes are due to TC, and the effective combination of labor, capital and the effect of scale have little effect, suggesting that improvement of internal structure is urgent. In addition, volatility due to the impact of the financial crisis in 2008 was much larger in SMEs than in large companies, so external economic impacts are more greater for SMEs than large enterprises. The relationship between TFP decomposition factors and exports shows that TC has a positive effect only on exports of SMEs. Therefore, in order to increase exports, in the case of SMEs, R&D support to promote technological development is needed. In the case of large companies, it is necessary to establish differentiated strategies for each export market, competitor company, and item to link efficiency and scale effect of exports.

• Journal of Korean Society of Forest Science
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• v.50 no.1
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• pp.56-71
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• 1980

To study the changes of vegetational composition of each plant successional stage of Pinus densiflora forest caused by pine gall midge damage, Thecodiplosis japonensis, located in Kyonggi-do area, the middle part of Korea, four districts, Anseong, Yongin, Gwangju, and Gapyeong, were selected according to the length of insect damage duration. The forest in the Anseong district was the noninfested one selected as the check. And forests in Yongin, Gwangju, and Gapyeong were the recent]y damaged, severely damaged, and damage prolonged ones in sequence. It was considered that this order could be in concord with the gradual transition of plant successional stage. In view of temperature, precipitation and soil factors, these four districts were sited within the same environment. Four survey plots were selected from each district and the distance between them was 3~4 km. Then again four subplots were set within a plot. Through needle accumulation after insect infestation, light intensity, soil moisture content, and the amount of soil organic matter were increased and these conditions could create a favorable environment enabling the new species invasion and their growth. These were naturally closely related with the increase in quantity of Pinus densiflora defoliation. After considerable time lapse, the quantities of above mentioned factors decreased with the development of the new substitute tree species. It was found that Quercus mongolica was an excellently substitute tree species come first in this studied area. Species diversity increased to a degree at the early stage of the duration of pine gall midge damage and decreased thereafter. As the same manner, similarity index value between plots in the same district decreased to a degree and increased thereafter. This was linked admittedly with the increase and decrease of tree species and evenness. Synthesizing above mentioned results, the process of plant succession studied quantitatively by changes of relative density and relative importance value, it can be concluded that Pinus densiflora forest gives way to Genus Quercus forest in which Genus Lespedeza and Genus Rhododendron species become as subdominance species after removal of the Pinus densiflora trees damaged by pine gall midge.

• Journal of Korean Society of Forest Science
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• v.54 no.1
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• pp.49-59
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• 1981

In order to elucidate the process of plant succession of the Japanese red pine forests caused by pine gall midge, Thecodoplosis japonensis, in the area of Chungbuk and Kyongbuk, 12 study plots, 4 plots from each three districts, were set up. Districts A (Cheongwon)not attacked by this insect, as the check, District B(Gumi) in which the insect outbreak occured 5 years ago, and District C(Yeongdong)in which the insect outbreak occured 10 years ago, were sampled. The surveyed were some environmental factors, the number of woody plants, relative density, relative dominance values, species composition of plots by layer(upper, middle and ground), importance values, species diversity, similarity and dissimilarity index, etc. The results obtained are summarized as follows: The accumulation of litter on the ground was increased with the lengthening the insect damage duration. Through the crown opening and litter accumulation, the light intensity, temperature condition and soil moisture and nutrient content might be altered. According to the changes of species composition were forced. In general, the Genus Quercus, as a compensation species, has sprung up. The relative importance values for Q.aliena, Q.serrata, and Q.variabilis were significantly increased in the insect infested forests. 2. the stand structure and species composition of the insect attacked forest about 5 years later after the outbreak become complex and diverse. However, since this time, the simplicity of these regards become restored up to 10 years after the outbreak. 3. As the synthetic analysis of plant succession process, the relative values calculated from the relative density and the relative dominance values shown the dominant status of Genus Quercus in the heavily damaged forests. In addition, Genus Rhododendron and Genus Lespedeza with higher frequency become the ground vegetation components. They were gradually increased along the time elapsing after the insect out-break. 4. The differences in connection with the soil moisture contents, the organic matter contents which might give some influences to the vegetation change were hardly recognizable statistically among the studied plots by three district groups. We estimated that the annual mean precipitation and the annual mean temperature did not operated any meaningful effects on the vegetation alteration among plots between districts.

• Proceedings of the KSCN Conference
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• 2003.11a
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• pp.1051-1052
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• 2003

미취학 아동기는 생후 1년 동안의 급격한 성장 이후로부터 학령기가 되기 전까지 성장이 완만해지는 시기이다. 이 시기의 아동들은 혼자 먹는 행동을 익히게 되고 식품에 대한 기호가 형성되는 등 식생활에서도 뚜렷한 개인특성을 갖게되며 이 시기에 형성된 식습관은 성인까지 이어지게 된다. 이 시기에 영양부족에 따른 신체발달의 지연이나 영양과잉에 따른 비만과 같은 과다한 신체발달의 문제점이 지적되고 있어 올바른 식습관 형성은 신체발달과 밀접한 관련성이 있는 것으로 보여진다. 우리나라는 취약한 칼슘섭취 부족에 따라 골격건강에 대한 관심이 크게 증가하고 있는데, 모든 질환이 그러하듯이 골격질환도 치료보다는 예방적인 관리가 다양한 측면에서 효율적이다. 따라서 골격건강과 최적의 신체발달을 위한 식사인자는 매우 중요하며, 일생의 성장시기에 따라 서로 다른 인자들이 관여할 것으로 생각된다. 이에 본 연구에서는 성장이 이루어지면서 식품선택의 독립성이 확립되는 미취학 아동에 있어 신체와 골격 발달에 관련성이 있는 영양섭취 요인을 찾아봄으로써 골격과 신체 발달을 위한 올바른 식습관 형성에 필요한 기초자료를 제시하고자 하였다. 이에 46~84개월의 미취학 어린이 총 62명(남자 37명, 여자 25명)을 대상으로 어머니에 의한 설문조사를 실시하고 대상자의 신체계측(InBody, Biospace)과 손목의 골밀도(DEXA, Medilink)를 측정하였다. 설문지는 어린이와 부모의 일반사항, 어린이의 건강상태, 식습관 및 활동조사표와 24시간 회상법에 의한 식사조사표로 구성하였다. 식사섭취조사 결과는 CAN-Pro를 이용하여 영양소 섭취량을 분석하였으며, 모든 연구결과는 SAS program을 이용하여 통계 분석하였다. 연구결과를 요약하면 다음과 같다. 남녀 어린이의 평균 월령은 62.43$\pm$7.26 개월과 62.12$\pm$8.85개월이었다. 출생시 신장과 체중은 남자 어린이가 50.92$\pm$2.14 cm와 3.36$\pm$0.42kg, 여자 어린이는 각각 50.29$\pm$1.36cm와 3.32$\pm$0.39kg이었다. 현재 신장과 체중은 남자 111.65$\pm$5.44 cm와 19.60$\pm$3.52kg, 여자 109.04$\pm$5.04 cm와 18.67$\pm$2.81kg이었으며, 비만지수는 남녀 각각 -2.13$\pm$9.09%와 0.22$\pm$10.49%였다. 손목의 골밀도는 남녀 어린이 각각 0.25$\pm$0.04g/cm, 0.24$\pm$0.03g/$\textrm{cm}^2$이었다. 에너지 섭취량은 남녀 어린이 각각 영양권장량의 66.43$\pm$18.58%와 70.46$\pm$20.31% 수준이었으며, 남녀 어린이 모두 단백질(124.97$\pm$37.55%, 131.24$\pm$45.49%), 비타민B$_{6}$ (152.48$\pm$47.01%, 152.95$\pm$61.77%), 엽산(106.87$\pm$40.44%, 104.52$\pm$50.16%), 비타민 E (121.04$\pm$52.79%, 113.48$\pm$75.78%)를 제외한 영양소 섭취량이 권장량에 미달되는 섭취수준을 보였다. 특히 성장기에 중요한 칼슘도 남녀 어린이 각각 권장량의 62.21$\pm$39.46%와 70.07$\pm$34.52%로 낮게 섭취하고 있었다. 모든 영양소 섭취량은 남녀 어린이간에 유의한 차이가 없었다. 신체계측치와 영양섭취와의 관계에서 체중, 체수분량, 제지방량은 각각 동물성 철 섭취량과 유의한 부의 상관관계를 보였다(p<0.05, p<0.01, p<0.01). 골밀도와 영양섭취와의 관계에서 손목 골밀도는 식물성 칼슘 섭취량과 유의한 정의 상관관계를 보였고(p<0.05), 특히 위쪽 손목 골밀도는 동물성 단백질, 동물성 철 섭취량과 각각 유의한 부의 상관을 보였다(p<0.05, p<0.05). 이상의 연구결과를 종합할 때 성장이 진행되고 있는 미취학 아동에 있어 신체상태와 골밀도는 동물성 단백질, 식물성 칼슘, 동물성 철 섭취량과 상관성이 있는 것으로 나타남으로써 앞으로 이들 영양소의 섭취가 신체와 골격 성장에 어떠한 영향을 미치는가에 대한 보다 세부적인 연구가 이루어져야 할 것으로 생각된다.