• Journal of Intelligence and Information Systems
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• v.23 no.2
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• pp.107-122
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• 2017

Volatility in the stock market returns is a measure of investment risk. It plays a central role in portfolio optimization, asset pricing and risk management as well as most theoretical financial models. Engle(1982) presented a pioneering paper on the stock market volatility that explains the time-variant characteristics embedded in the stock market return volatility. His model, Autoregressive Conditional Heteroscedasticity (ARCH), was generalized by Bollerslev(1986) as GARCH models. Empirical studies have shown that GARCH models describes well the fat-tailed return distributions and volatility clustering phenomenon appearing in stock prices. The parameters of the GARCH models are generally estimated by the maximum likelihood estimation (MLE) based on the standard normal density. But, since 1987 Black Monday, the stock market prices have become very complex and shown a lot of noisy terms. Recent studies start to apply artificial intelligent approach in estimating the GARCH parameters as a substitute for the MLE. The paper presents SVR-based GARCH process and compares with MLE-based GARCH process to estimate the parameters of GARCH models which are known to well forecast stock market volatility. Kernel functions used in SVR estimation process are linear, polynomial and radial. We analyzed the suggested models with KOSPI 200 Index. This index is constituted by 200 blue chip stocks listed in the Korea Exchange. We sampled KOSPI 200 daily closing values from 2010 to 2015. Sample observations are 1487 days. We used 1187 days to train the suggested GARCH models and the remaining 300 days were used as testing data. First, symmetric and asymmetric GARCH models are estimated by MLE. We forecasted KOSPI 200 Index return volatility and the statistical metric MSE shows better results for the asymmetric GARCH models such as E-GARCH or GJR-GARCH. This is consistent with the documented non-normal return distribution characteristics with fat-tail and leptokurtosis. Compared with MLE estimation process, SVR-based GARCH models outperform the MLE methodology in KOSPI 200 Index return volatility forecasting. Polynomial kernel function shows exceptionally lower forecasting accuracy. We suggested Intelligent Volatility Trading System (IVTS) that utilizes the forecasted volatility results. IVTS entry rules are as follows. If forecasted tomorrow volatility will increase then buy volatility today. If forecasted tomorrow volatility will decrease then sell volatility today. If forecasted volatility direction does not change we hold the existing buy or sell positions. IVTS is assumed to buy and sell historical volatility values. This is somewhat unreal because we cannot trade historical volatility values themselves. But our simulation results are meaningful since the Korea Exchange introduced volatility futures contract that traders can trade since November 2014. The trading systems with SVR-based GARCH models show higher returns than MLE-based GARCH in the testing period. And trading profitable percentages of MLE-based GARCH IVTS models range from 47.5% to 50.0%, trading profitable percentages of SVR-based GARCH IVTS models range from 51.8% to 59.7%. MLE-based symmetric S-GARCH shows +150.2% return and SVR-based symmetric S-GARCH shows +526.4% return. MLE-based asymmetric E-GARCH shows -72% return and SVR-based asymmetric E-GARCH shows +245.6% return. MLE-based asymmetric GJR-GARCH shows -98.7% return and SVR-based asymmetric GJR-GARCH shows +126.3% return. Linear kernel function shows higher trading returns than radial kernel function. Best performance of SVR-based IVTS is +526.4% and that of MLE-based IVTS is +150.2%. SVR-based GARCH IVTS shows higher trading frequency. This study has some limitations. Our models are solely based on SVR. Other artificial intelligence models are needed to search for better performance. We do not consider costs incurred in the trading process including brokerage commissions and slippage costs. IVTS trading performance is unreal since we use historical volatility values as trading objects. The exact forecasting of stock market volatility is essential in the real trading as well as asset pricing models. Further studies on other machine learning-based GARCH models can give better information for the stock market investors.

• The KIPS Transactions:PartA
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• v.15A no.5
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• pp.249-258
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• 2008

DCDN(Distributed Contents Delivery Network) as known the next generation of CDN is to exploit the resource of client PCs based on P2P technology to provide low cost, high scalability and high speed services when contents are delivered. This DCDN has two problems. One is that DCDN can't provide a sustainable service because client PCs are on/off irregularly and their on times tend to focus on specific time zone, and the other is that client PCs can not be accessed outside in DCDN if they are behind NAT or Firewall. In this paper, we present a distributed contents delivery network based on home gateway for a sustainable service. If home gateway is used in DCDN instead of client PC, it can solve the two existing problems of DCDN. That is, home gateway can provide a sustainable service because it is on during all day and it is not behind NAT and Firewall. The proposed method is implemented with ASUS WL-500GP, a wired/wireless router. Experimental results show the effectiveness of the proposed method compared to the existing method of DCDN.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.209-220
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• 2003

Modification of general Hoek and Brown criterion is carried out to estimate the shaft resistance of drilled shaft socketed into rock mass. Since the general Hoek-Brown criterion can consider the in-situ state of the rock mass, the proposed method, estimating the unit shaft resistance of drilled shafts based on the Hoek-Brown criterion, has increased flexibility compared to other methods exclusively considering uniaxial compressive strength of intact rocks. The proposed method can form the upper and lower bounds, and most culled data (from 21 pile load tests) from the literature can be found between these two bounds. A comparison between the estimated and observed unit shaft resistances shows quite a good correlation even with crude assumptions for the input parameters. The best-fit line drawn from this analysis shows that at the lower strength of intact rocks (up to 10MPa), Horvath and Kenney's equation shows a good correlation with the measured values, and fur strong rocks Rosenberg and Journeaux's equation provides a close estimation with colleted data. The results of parametric studies for GSI and confining stress show that the normalized unit shaft resistance increases with these two factors. In addition, coefficient of the equational form of the estimation can vary with GSI and confining stresses.

• 대한예방의학회:학술대회논문집
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• 2002.05a
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• pp.73-83
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• 2002

우리 사회에서 일정 정도 이상의 사회와 가정에서의 기능상의 부적응을 초래하는 정신적 문제는 경제활동인구에 있어 가장 흔한 보건의료상의 문제일 것으로 추측되고 있으나, 현재까지는 정신보건제도 마련에 있어 가장 극심한 부적응을 보이는 정신적 장애를 지닌 환자를 위주로 수용시설과 지역사회에서의 재활과 관리에 그 초점을 두어 왔다. 즉 직업스트레스와 같은 일시적인 사회심리적 갈등으로 인한 신체증상의 호소나 알을 및 약물중독으로 인한 사고의 발생으로부터 일생동안 관리되어야 하는 지능저하나 학습장애와 같은 만성적인 문제에 이르기까지 다양한 스펙트럼을 보이는 사업장과 지역사회에서의 정신적 문제들 중 그 일부만이 제도적으로 관리되어 왔다. 실제 그 동안 직장 내 정신보건문제에 대한 행정적 관심은 일부 장애인의 취업 문제를 제외하고는 없었다고 하여야 할 것이다. 그러나 한편으로 우리 사회의 산업구조와 경제사회적 조건의 변화에 따른 노동내용과 조건상 유연화의 증대가 많은 직장에서 노동강화로 이어진다는 점, 그리고 가족 및 교류집단을 비롯한 전통적인 사회적 지지구조가 와해되고 있다는 점과 정신적 문제로 인한 기능상 부적응의 척도가 한편으로 사회적 가치관의 변화에 따라 계속 그 영역이 넓어지는 방향으로 변화하고 있다는 점등에서 직장 내 정신보건 문제는 앞으로 더욱 그 비중이 커질 것으로 판단되고 있다. 문제의 심각성에 대한 관심이 요구되는 현재의 시점에서 제도적 접근에 대한 검토 또한 시작되어야 할 것으로 판단되고 있다. 현재까지 기업 내에서 이루어지고 있는 정신보건관리의 현황을 단편적으로 파악해 보았을 때, 단지 일부 기업에서 취업시 내지는 부서 배치시 성격검사를 비롯하여 적성검사를 실시하고 있으며, 기업윤리확보 차원에서 비정규적으로 사기앙양을 주목적으로 하는 집단적인 교육이나 단체훈련이 이루어지고 있으나, 정신심리적 문제를 개인적 차원에서 그리고 또한 조직적 차원에서 체계화된 프로그램으로 관리하고 있는 사례는 아직 없다. 앞으로 직장 내 정신보건문제에 대하여 제도적인 접근을 하기 위하여서는 다음과 같은 세가지 조건들이 구비되어야 할 것으로 판단된다. 첫 번째로 문제점 그 자체의 내용과 그 규모에 대한 정확한 파악과 예측이 가능하여야 한다. 즉 제도 전체의 운영을 객관적으로 평가하고 개선할 수 있는 기제가 함께 있어야 제도가 실제적인 기능을 할 수 있다는 최소한의 목적이 달성될 수 있다. 두 번째로 문제점의 관리를 위한 효과적인 개입내용 및 개입지점의 확보가 가능하여야 한다. 특히 직장 내에서 수행할 수 있는 프로그램이 개발되어야 하며, 이는 시범사업과 시장을 통한 소비자, 즉 사업주들의 자발적인 선택을 통하여 검토되고 걸려져야만 한다. 마지막으로 제도 운영의 대상, 특히 정신보건문제를 안고 있는 노동자들의 자발적인 동의가 확보될 수 있어야 한다. 이는 정신적 문제가 안고 있는 편견과 그로 인한 차별이 가져다주는 문제를 함께 고려하면서 제도가 운영되어야 하며, 이에 있어 제도 운영상 노동자들의 주체적인 참여가 필요하기 때문이다. 이상 고려되는 직장 내 정신보건문제에 대한 제도적 접근을 담기 위하여서는 프로그램 개발이나 전문가 집단의 양성과 같은 단순한 기술적 접근과 이들의 인허가 및 사업화에 따른 적용기준 및 의무의 설정과 같은 제도적 접근에 그쳐서는 그 실효성을 담보하지 못할 것으로 판단된다. 보다 중요한 것은 이러한 정신보건문제에 대한 노사의 공감대를 이루어 내는 것이며, 사회 전반적인 인식의 확산과 더불어 바람직한 관리모습에 대한 사회적 가치관을 도출해 내는 것이 제도적인 접근의 성공을 보장할 수 있는 기반 조건이 될 것이다. 이러한 점에 있어 정신보건문제를 바라보는 기존의 가치관이 부정적이고 고착화된 모습만을 강조하였으나, 이제는 점차 긍정적이 사회활동에 수반되는 역동적인 모습으로서 비추어지는 것이 많아진다는 측면에서 그 전망을 밝게 하여 주고 있다.

• Journal of Gifted/Talented Education
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• v.25 no.3
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• pp.439-463
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• 2015

This study compared 14 programs for the economically disadvantaged or minority students with potentials in 5 countries - US, UK, Germany, Australia, and Israel, attempting contents and characters of Korean Head Start to be developed, that is the program for economically disadvantaged gifted students or students from multi-cultural families, who are gifted at risk of under-representation and under-achievement. School wide enrichment programs, which served all students with gifted programs, using RTI model in the pursuit of equity and excellence, turned out to be effective as early interventions and identification implemented for economically disadvantaged or minority students with potentials. Gifted programs for low Social Economic Status (SES) or minority students played a role as a bridge for disadvantaged students to get into a regular gifted program or even higher gifted schools and to have a competency to compete with affluent gifted students. The principles of the programs were acceleration and differentiation. Most programs also ran a parents' education and a mentor program to motivate and support disadvantaged students socially and emotionally. Collaboration among governmental offices and usage of external resources were more effective to support these students and the programs.

• Journal of Hospice and Palliative Care
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• v.12 no.2
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• pp.80-87
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• 2009

Purpose: The purposes of this study were to identify the types of widow's bereavement experience and understand the nature of it's bereavement by using Q-methodological approach. Methods: Contents Q sample included 46 statements obtained from literatures and interviews with 5 widows. P sample consisted of 13 widows who bereaved within 2 years. The data were collected from October 2004 to December 2006 and analyzed using Quanal program. Results: Two types of widow's experience were found. Type 1 was characterized by loss suffering, and type 2 was characterized by acceptance and adaptation Conclusion: Widows were found to experience different types of bereavement. Therefore, bereavement care team should assess the types of suffering pain and provide appropriate care to the widows. Also, need to be developed programs to relieve or prevent suffering of bereavement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.664-675
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• 2016

The purpose of the study was to explore the nurses' perception of flexible working and present an operational guideline for implementation. The data were collected from a survey of 532 nurses conducted from 10 February to 24 February, 2015, using simple random sampling. SPSS 21.0 was used to analyze the data. This study found that the demanding for shorter hour shifts was highest ($M=3.89{\pm}0.87$) and 242 participants (46.2%) intended to apply the shift, followed by a fixed night shift, fixed weekend shift, and 12 hour shift. The common reasons identified were the poor environment of shift work and the challenges of child care. The increased time for personal development, relaxation activity to improve the quality of life and child care was highlighted and work-life balance was noted as a positive impact of flexible working. The negative impacts of flexible working were being likely to become temporary workers. These results can help establish uniform working conditions of nurses in the future by providing a standardized operational guideline as a precondition for reasonable compensation and working environment according to a flexible working pattern.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.4
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• pp.271-279
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• 1989

Mean values representing the particle size distribution and some chemical properties for the cultivated soils were obtained from the analysis results of the typical profiles, which were described by the detailed soil maps throughout Korea. Analysis results of 5,215 soil samples (3,075 for paddy and 2,140 for upland) were available for the determination of mean values. The results are under. 1. Paddy topsoil contained 20.4% for clay, 5.8 for pH, 2.6% for organic matter, 10.4me/100g for exchangeable K, and 89ppm for available $P_2O_5$. Upland topsoil did 17.3% for clay, 5.5 for pH, 1.8% for organic matter, 9.lme/100g for CEC, 0.29me/100g for exchangeable K, and 103ppm for availabal $P_2O_5$. 2. Soil properies for paddy were markedly influenced by the reliefs. Topsoil contained 21.4% for clay, 6.0 for pH, 2.2% for organic matter, 10.8me/100g for CEC, 0.39me/100g for exchang-cable K and 57ppm for available $P_2O_5$ on the fluvio-marine plain, 15.3%, 5.7, 2.0%, 8.6me/100g, 0.17me/100g and 76ppm on the alluvial plain, 18.8%, 5.9, 2.7%, 10.4me/100g, 0.19me/100g and 80ppm on the valleys and fans, 25.0%, 5.7, 2.5%, 11.5me/100g, 0.26me/100g, 0.27me/100g and 141ppm on the moutain foot slopes, respectively. 3. Soil Properties for upland, also, were markedly influenced by the reliefs. Topsoil contained 5.5% for clay, 5.7 for pH, 1.1% for organic matter, 4.7me/100g for CEC, 0.17me/100g for exchangeable K and 50ppm for available $P_2O_5$ on the fluvio-marine plain, 10.3%, 5.5, 1.4%, 7.6me/100g, 0.26me/100g and 160ppm on the alluvial plain, 13.9%, 5.4, 1.8%, 9.3me/100g, 0.24me/100g and and 184ppm on the valleys and fans, 29.8%, 5.3, 2.1%, 11.2me/100g 0.40me/100g and 58ppm on the alluvial plain, 20.0%, 5.7, 2.7%, 11.4me/100g, 0.32me/100g and 116ppm on the mountain foot slopes, and 24.6%, 5.3, 1.8%, 10.2me/100g, 0.28me/100g and 51ppm on the rolling and Hill. 4. All chemical properties did not reach the ideal value for maximizing land capability. 5. Organic matter, exchangeable cations and available $P_2O_5$ were not normally distributed. Intervals of one and two standard deviations about mean of an approximately normal distribution were calculated.

• Journal of Korean Home Economics Education Association
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• v.33 no.4
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• pp.49-64
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• 2021

Apprenticeship education in Korea started approximately in 2005, and is divided into government-led apprenticeship education and Gyeonggi-do-led apprenticeship education. Apprenticeship education for textile and clothing-related majors in Korea is a very different process compared to Germany, where the country, companies, and schools have cooperated with each other with a long tradition, and there are many points to be supplemented. In order to explore the literature on apprenticeship education in Germany and Korea, and to understand the phenomena or actual conditions that have not been shown in the literature, interviews were conducted with two German professors living in South Korea. As a result of the analysis, Germany's long tradition and positive perception of vocational education are the basis for the establishment of apprenticeship education, and it is positioned as a system of education process. Various associations related to apprenticeship education make systematic training manuals, and then distribute certificates to trainees who have completed these courses. Therefore, companies promote the stability of the job market by educating local talents through apprenticeship training to nurture industrial manpower. Currently, in Korea's apprenticeship education, a series of procedures for developing educational courses such as company discovery and job analysis for each company are entirely entrusted to vocational high schools. Therefore, public confidence and solidity in apprenticeship education were found to be insignificant. This study has limitations in that it cannot confirm a phenomenon that has not been shown in the literature review, there is insufficient research on German literature, and the number of samples interviewed is small. However, if, based on the results of this study, an association dedicated to apprenticeship education is created in Korea and a systematic curriculum is developed, it will be able to contribute to establishing the stability of the textile and apparel labor market in the future.

• Journal of the Korean earth science society
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• v.38 no.7
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• pp.511-521
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• 2017

This study analyzes Two-dimensional video disdrometer (2DVD) data while summer 2011-2012 in Daegu region and compares with Marshall and Palmer (MP) distribution to find out statistical characteristics and characteristics variability about drop size distribution (DSD) of Daegu region. As the characterize DSD of Daegu region, this study uses single moment parameters such as rainfall intensity (R), reflectivity factor (Z) and double moment parameters such as generalized characteristics number concentration ($N{_0}^{\prime}$) and generalized characteristics diameter ($D{_m}^{\prime}$). Also, this study makes an assumption that DSD function can be expressed as general gamma distribution. The results of analysis show that DSD of Daegu region has ${\log}_{10}N{_0}^{\prime}=2.37$, $D{_m}^{\prime}=1.04mm$, and c =2.37, ${\mu}=0.39$ on average. When the assumption of MP distribution is used, these figures then end up with the different characteristics; ${\log}_{10}N{_0}^{\prime}=2.27$, $D{_m}^{\prime}=0.9mm$, c =1, ${\mu}=1$ on average. The differences indicate liquid water content (LWC) of Daegu distribution is generally larger than MP distribution at equal Z. Second, DSD shape of Daegu distribution is concave upward. Other important facts are the characteristics of Daegu distribution change when Z changes. DSD shape of Daegu region changes concave downward (c =2.05~2.55, ${\mu}=0.33{\sim}0.77$) to cubic function-like shape (c =3.0, ${\mu}=-0.13{\sim}-0.33$) at Z > 45 dBZ. 35 dBZ ${\leq}$ Z > 45 dBZ group of Daegu distribution has characteristics similar to maritime cluster of diverse climate DSD study. However, Z > 45 dBZ group of Daegu distribution has a difference from the cluster.