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

• Korean Journal of Weed Science
• /
• v.12 no.1
• /
• pp.70-79
• /
• 1992

From the beginning of the chosun dynasty, an agriculture-first policy was imposed by being written farming books, for instance, Nongsajiksul, matched with real conditions of local agriculture, which provided the grounds of new, intensive farming technologies. This farming book was the collection of good fanning technologies that were experienced in rural farm areas at that time. According to Nongsajiksul, rice culture systems were divided into "Musarmi"(Water-Seeded rice), /"Kunsarmi"(dry-seeded rice), /transplanted rice and mountainous rice (upland rice) culture. The characteristics of these rice cultures with high technologies were based of scientific weeding methods, improved fertilization, and cultivation works using cattle power and manpower tools systematically. Reclamation of coastal swampy and barren land was possible in virtue of fire cultivation farming(火耕) and a weeding tool called "Yoonmok"(輪木). Also, there was an improved hoe to do weeding works as well as thinning and heaping-up of soil at seeding stages of rice. Direct-seeded rice culture in flat paddy fields were expanded by constructing the irrigation reservoirs and ponds, and the valley paddy fields was reclaimed by constructing "Boh(洑)". These were possible due to weed control by irrigation waters, keeping soil fertility by inorganic fertilization during irrigation, and increased productivity of rice fields by supplying good physiological conditions for rice. Also, labor-saving culture of rice was feasible by transplanting but in national-wide, rice should not basically be transplanted because of the restriction of water use. Thus, direct-seeded rice in dry soils was established, in which rice was direct-seeded and grown in dry soils by seedling stages and was grown in flooded fields when rained, as in the book "Nongsajiksul". During the middle of the dynasty(AD 1495-1725), the excellent labor-saving farmings include check-rowing transplanting because of weeding efficiency and availability in rice("Hanjongrok"), and, nurserybed techniques (early transplanting of rice) were emphasized on the basis of rice transplanting ["Nongajibsung"]. The techniques for deep plowing with cattle powers and for putting more fertilizers were to improve the productivity of labor and land, The matters advanced in "Sanlimkyungje" more than in "Nongajibsung" were, development of "drybed of rice nursery stock", like "upland rice nursery" today, transplanting, establishment of "winter barly on drained paddy field, and improvement of labor and land-productivity in rice". This resulted in the community of large-scale farming by changing the pattern of small-farming into the production system of rice management. Woo-hayoung(1741-1812) in his book "Chonilrok" tried to reform from large-scale farmings into intensive farmings, of which as eminent view was to divide the land use into transplanting (paddy) and groove-seeding methods(dry field). Especially as insisted by Seo-yugo ("Sanlimkyungjeji"), the advantages of transplanting were curtailment of weeding labors, good growth of rice because of soil fertility of both nurserybed and paddy field, and newly active growth because rice plants were pulled out and replanted. Of course, there were reestimation of transplanting, limitation of two croppings a year, restriction of "paddy-upland alternation", and a ban for large-scale farming. At that period, Lee-jiyum had written on rice farming technologies in dry upland with consider of the land, water physiology of rice, and convenience for weeding, and it was a creative cropping system to secure the farm income most safely. As a integrated considerations, the followings must be introduced to practice the improved farming methods ; namely, improvement of farming tools, putting more fertilizers, introduction of cultural technologies more rational and efficient, management of labor power, improvement of cropping system to enhance use of irrigation water and land, introduction of new crops and new varieties.

• Journal of dental hygiene science
• /
• v.5 no.4
• /
• pp.211-220
• /
• 2005

The purpose of this study was to examine the job performance of dental coordinators and their perception of their job to lay the groundwork for utilizing dental personnels more efficiently. The subjects in this study were dental coordinators who worked at selected dental hospitals and clinics in Seoul, Gyeonggi province and Incheon. A survey was conducted to gather data from May 1 to August 8, 2005 and answer sheets from 108 respondents were analyzed. The findings of the study were as follows: 1. As for the length of service, 43.5 percent of the dental coordinators investigated had worked at dental institutes for five years or more, which was followed by less than two years(19.5%) and three years to less than five years(19.4%). Concerning the length of service as dental coordinators, 39.8 percent had served for less than two years, and 19.4 percent had worked for two years to less than three years and for five years or more respectively. Regarding the name of position, 38 percent were called team leaders, and 30.6 percent were called coordinators. As to duties, the largest group of them that stood at 30.6 percent were in charge of receiving, and in regard to department, the largest group, 57.4 percent, belonged to the treatment backup department. 2. Concerning education, the greatest number of them, 45.4 percent, had received education at private institutes, and 73.1 percent found it necessary for dental coordinators to take an authorized qualification test. 43.5 percent, the largest group, looked upon the central government as the best organization to authorize their qualifications and 70.8 percent believed that what they learned enabled them to perform their job successfully. As to the necessity of follow-up education as a means to improve job performance, 96.3 percent consented to it. As for the reason, 63.9 percent considered that necessary to enhance their own ability and 22.2 percent were in want of systematic education. Regarding educational expenses, 29.6 percent were subsidized by the dental institutes where they had worked and 25.9 percent had totally been responsible for that. Regarding a required course, medical service and marketing was most widely pointed out(66.7%), followed by theory and practice(65.7%) and introduction to dentistry(57.4%). As to what sort of education they wanted to receive more, dental service and marketing was selected the most, followed by practical health insurance(35.2%). 3. In regard to what type of job they performed as dental coordinators, 88.9 percent were in charge of appointment in the field of customer service, and 87.9 percent paid attention to having good manners as service providers in the area of self-management. In the field of hospital affairs, 81.3 percent were in charge of receiving. 4. As to their awareness of dental coordinator job, the largest group took pride in the job they performed ($3.99{\pm}0.76$), and the second largest group believed that dental coordinators made a great contribution to hospital management ($3.92{\pm}0.70$). The third largest group gave a great weight to their own job ($3.91{\pm}0.84$) in light of overall dental duties and the fourth largest group found themselves to get along with other employees regardless of position ($3.86{\pm}0.74$). The fifth largest group believed their job was of great use for promoting the oral health of patients ($3.76{\pm}0.75$), and the sixth largest group thought the future of dental coordinators was promising($3.74{\pm}0.86$). 5. In regard to their perception by age group, those who were older had a better opinion on every item of their job in general. Their age made a statistically significant difference to their view of the weight of dental coordinator job(P < 0.001) in light of overall dental duties, of being approved and trusted by managers(P < 0.01), of social awareness of dental coordinator, and of being understood and approved by other employees and dentists. Their pride in current job and their satisfaction with the name of their position were statistically significantly different according to their age as well. Besides, their age made a statistically significant difference to their opinion about whether or not there was an age limit to their occupation and about their contribution to hospital management (P < 0.05). 6. As for their perception by type of job, the dental hygienists were generally most satisfied with their job, followed by nursing aids and others. There was a statistically significant gap among their opinions about whether to make a job-related decision on their own(P < 0.001). the weight of their job in terms of overall dental duties, whether their job improved their ability, whether their job made a great contribution to enhancing the oral health of patients, whether their job was understood and approved by other employees(P < 0.01), social awareness of their job, whether they conflicted with other employees during job performance, and whether dental hospitals or clinics offered a self-development opportunity for them to take their ability to another level(P < 0.05). And their satisfaction with current pay was statistically significantly different as well.

• Journal of Korean Home Economics Education Association
• /
• v.29 no.4
• /
• pp.161-193
• /
• 2017

The purpose of this study was to develop and evaluate pre-parenthood education program(PPEP) based on Home Economics(HE) subject for high school students. The development and evaluation of PPEP based on HE subject in this study followed ADDIE model except implementation through 4 processes such as analysis, design, development, and evaluation. First, program development directions were set in three aspects such as 'general development', 'contents', and 'teaching and learning methods'. Themes of the program are 11 in total such as '1. Parenting, what is being a parent', '2. Choosing your spouse, happy marital relationship, the best gift to your children', '3. Pregnancy and birth, a moving meeting with a new life', '4. Taking care of a new born infant for 24 hours', '5. Taking care of infants, relationship with my lovely baby, attachment', '6. Taking care of young children, my child from another planet', '7. Parents and children in healthy family', '8. Parent-child relationship, wise parents to make effective interaction with their children', '9. Parents safety manager at home,', '10. Practice to take care of infants', and '11. Practice of community nurturing support service development'. In particular, learning activities of the program have major characteristics such as 1) utilization of cases including practice problems related to parenting, 2) community exchange activities utilizing learned knowledge and techniques, 3) actual life project activities utilizing learning contents related with parenting, 4) activities inducing positive changes in current life of high school students, and 5) practice activities for the necessities of life such as food, clothing and shelter supporting development of children. Second, the program was developed according to the design. Teaching-learning plans and materials for 17 classes were developed according to 11 themes. The developed plans include class flow and teacher's reference. It starts with receiving a class-related message from a virtual child at the introduction stage and ended with replying to the message by summarizing contents of the class and making a promise as a parent-to-be. That is the basic frame of class flow. Learning materials included various plans and reports necessary for learning activities and they are prepared in details so that they can be play the role of textbooks in regular curriculum. Third, evaluation of developed program was executed by a 5 point Likert scale survey on 13 HE experts on two aspects of program development process and program development results. In the evaluation of development process, mean value was 4.61 and index of content validity was 97.4%. For development results, mean value was 4.37 and index of content validity was 86.9%. These values showed that validity in the development process and results in this study was highly secured and confirmed that PPEP based on HE was appropriate and valid to enhance parent qualifications of high school learners.

• The Korean Journal of Air & Space Law and Policy
• /
• v.30 no.2
• /
• pp.83-153
• /
• 2015

As our economy grows and the number of aircraft increase, the number of civil execution against aircraft cases are likely to increase as well in the future. The purpose of this article is to present the legal theory on the civil execution against aircrafts by drawing on the legal theory on the civil execution against vessels which constitute a relatively large number of cases thus observed. The provisions of the civil execution against immovables or vessel, shall basically apply mutatis mutandis to the civil execution against aircraft or light aircraft. The civil execution against ultra-light flying devices or a foreign aircraft shall be executed in conformity with the civil execution against movables. There are a compulsory auction, an auction to execute a security right to aircraft, and an auction under the right of retention, etc. in the civil execution against an aircraft. A compulsory execution against an aircraft means an execution carried out by a creditor against a debtor's aircraft to obtain satisfaction of claims for the purpose of payment of money. The court of execution of a compulsory execution against an aircraft shall be the district court having jurisdiction over the airport of stoppage or storage of such aircraft at the time of seizure. The forums of execution of a compulsory execution against an aircraft shall be exclusive forums. When a court has rendered an order on commencing an auction, it shall order an execution officer to receive a certificate of the aircraft's registration and other documents as required for its operation, and to submit them to the court. A court may revoke the procedures for a compulsory auction when an execution officer fails to obtain a transfer of the aircraft's registration certificate, etc. and the location of the aircraft is not evident, not later than an elapse of 2 months from the date on which an order on commencing an auction has been rendered. In the case where it is deemed that there exists a business-related need or other based on proper reasoning, the court may permit the aircraft's operation, upon the motion submitted by the debtor. In this case, there shall be a consent from the creditor, the highest bidder, the next highest bidder and successful bidder. A court may, upon a motion submitted by the creditor, make the dispositions required for observing and preserving the aircraft. When a debtor has submitted the documents under subparagraph 2 or 4 of the Article 49 of the Civil Execution Act, and furnished the guarantee equivalent to the claims of the execution creditors and the creditors demanding a distribution and to the costs for execution, before a declaration of bid, the court shall, upon request, revoke other procedures than those for distribution. The provisions of a obligatory auction against vessel or aircraft and an auction to execute a security right to real estate or vessel, shall apply mutatis mutandis to an auction to execute the security right to aircraft. In an auction to execute the security right to aircraft case, an executive title is not necessary. An executory exemplification is not necessary in an application for an auction to execute the security right to aircraft. A court should examine the existence of security right and claim secured. No order on commencing an auction procedure shall be issued with non-existence or invalidity of the security right and absence or extinguishment of the claim secured. Furthermore, these prohibitions are the reason of a decision on non-permit for sale, the court overlooked these prohibitions, and the decision on a permit for sale became final and conclusive, the successful bidder who paid the price and registered of ownership could not acquire ownership of the aircraft sold. A court may render a ruling to put plural aircrafts up for a blanket auction, only when they are in restraint and related matter (Supreme Court Order 2001Ma3688 dated on August 22, 2001). A righter of retention on aircraft may file a request for an auction against the aircraft. The provisions of an auction to execute a security right to aircraft shall apply mutatis mutandis to the formal auction. Airport facility fee and an aircraft are not in restraint and related matter, so an airport management corporation does not hold the right of retention on the aircraft (Supreme Court Decision 2011Da29291 decided on April 10, 2014). In an auction in accordance with the right of retention, all encumbrances (e.g., mortgages) on the sold aircraft shall be extinguished by a sale under the legal conditions for sale. Not only creditors who have claims for preferential payment but also general creditors could demand for distribution. The precedence of the claim of the right of retention on aircraft and that of general creditor's claims are equal.