• Title/Summary/Keyword: S-형

Search Result 21,755, Processing Time 0.059 seconds

Steroid Effect on the Brain Protection During OPen Heart Surgery Using Hypothermic Circulatory Arrest in the Rabbit Cardiopulmonary bypass Model (저체온순환정지법을 이용한 개심술시 스테로이드의 뇌보호 효과 - 토끼를 이용한 심폐바이패스 실험모델에서 -)

  • Kim, Won-Gon;Lim, Cheong;Moon, Hyun-Jong;Chun, Eui-Kyung;Chi, Je-Geun;Won, Tae-Hee;Lee, Young-Tak;Chee, Hyun-Keun;Kim, Jun-Woo
    • Journal of Chest Surgery
    • /
    • v.30 no.5
    • /
    • pp.471-478
    • /
    • 1997
  • Introduction: The use of rabbits as a cardiopulmonary bypass(CPB) animal model is extremely dif%cult mainly due to technical problems. On the other hand, deep hypothermic circulatory arrest(CA) is used to facilitate surgical repair in a variety of cardiac diseases. Although steroids are generally known to be effective in the treatment of cerebral edema, the protective effects of steroids on the brain during CA are not conclusively established. Objectives of this study are twofold: the establishment of CPB technique in rabbits and the evaluation of preventive effect of steroid on the development of brain edema during CA. Material '||'&'||' Methods: Fifteen New Zealan white rabbits(average body weight 3.5kg) were divided into three experimental groups; control CA group(n=5), CA with Trendelenberg position group(n=5), and CA with Trendelenberg position + steroid(methylprednisolone 30 mglkg) administration group(n=5). After anesthetic induction and tracheostomy, a median sternotomy was performed. An aortic cannula(3.3mm) and a venous ncannula(14 Fr) were inserted, respectively in the ascending aorta and the right atrium. The CPB circuit consisted of a roller pump and a bubble oxygenator. Priming volume of the circuit was approximately 450m1 with 120" 150ml of blood. CPB was initiated at a flow rate of 80~85ml/kg/min, Ten min after the start of CPB, CA was established with duration of 40min at $20^{\circ}C$ of rectal temperature. After CA, CPB was restarted with 20min period of rewarming. Ten min after weaning, the animal was sacrif;cod. One-to-2g portions of the following tissues were rapidly d:ssected and water contents were examined and compared among gr ups: brain, cervical spinal cord, kidney, duodenum, lung, heart, liver, spleen, pancreas. stomach. Statistical significances were analyzed by Kruskal-Wallis nonparametric test. Results: CPB with CA was successfully performed in all cases. Flow rate of 60-100 mlfkgfmin was able to be maintained throughout CPB. During CPB, no significant metabolic acidosis was detected and aortic pressure ranged between 35-55 mmHg. After weaning from CPB, all hearts resumed normal beating spontaneously. There were no statistically significant differences in the water contents of tissues including brain among the three experimental groups. Conclusion: These results indicate (1) CPB can be reliably administered in rabbits if proper technique is used, (2) the effect of steroid on the protection of brain edema related to Trendelenburg position during CA is not established within the scope of this experiment.

  • PDF

Analysis of dose reduction of surrounding patients in Portable X-ray (Portable X-ray 검사 시 주변 환자 피폭선량 감소 방안 연구)

  • Choe, Deayeon;Ko, Seongjin;Kang, Sesik;Kim, Changsoo;Kim, Junghoon;Kim, Donghyun;Choe, Seokyoon
    • Journal of the Korean Society of Radiology
    • /
    • v.7 no.2
    • /
    • pp.113-120
    • /
    • 2013
  • Nowadays, the medical system towards patients changes into the medical services. As the human rights are improved and the capitalism is enlarged, the rights and needs of patients are gradually increasing. Also, based on this change, several systems in hospitals are revised according to the convenience and needs of patients. Thus, the cases of mobile portable among examinations are getting augmented. Because the number of mobile portable examinations in patient's room, intensive care unit, operating room and recovery room increases, neighboring patients are unnecessarily exposed to radiation so that the examination is legally regulated. Hospitals have to specify that "In case that the examination is taken out of the operating room, emergency room or intensive care units, the portable medical X-ray protective blocks should be set" in accordance with the standards of radiation protective facility in diagnostic radiological system. Some keep this regulation well, but mostly they do not keep. In this study, we shielded around the Collimator where the radiation is detected and then checked the change of dose regarding that of angles in portable tube and collimator before and after shielding. Moreover, we tried to figure out the effects of shielding on dose according to the distance change between patients' beds. As a result, the neighboring areas around the collimator are affected by the shielding. After shielding, the radiation is blocked 20% more than doing nothing. When doing the portable examination, the exposure doses are increased $0^{\circ}C$, $90^{\circ}C$ and $45^{\circ}C$ in order. At the time when the angle is set, the change of doses around the collimator decline after shielding. In addition, the exposure doses related to the distance of beds are less at 1m than 0.5m. In consideration of the shielding effects, putting the beds as far as possible is the best way to block the radiation, which is close to 100%. Next thing is shielding the collimator and its effect is about 20%, and it is more or less 10% by controlling the angles. When taking the portable examination, it is better to keep the patients and guardians far enough away to reduce the exposure doses. However, in case that the bed is fixed and the patient cannot move, it is suggested to shield around the collimator. Furthermore, $90^{\circ}C$ of collimator and tube is recommended. If it is not possible, the examination should be taken at $0^{\circ}C$ and $45^{\circ}C$ is better to be disallowed. The radiation-related workers should be aware of above results, and apply them to themselves in practice. Also, it is recommended to carry out researches and try hard to figure out the ways of reducing the exposure doses and shielding the radiation effectively.

Characteristics of Manure and Estimation of Nutrient and Pollutant of Holstein Dairy Cattle (홀스타인 젖소 분뇨의 특성과 비료성분 및 오염물질 부하량 추정)

  • Choi, D.Y.;Choi, H.L.;Kwag, J.H.;Kim, J.H.;Choi, H.C.;Kwon, D.J.;Kang, H.S.;Yang, C.B.;Ahn, H.K.
    • Journal of Animal Science and Technology
    • /
    • v.49 no.1
    • /
    • pp.137-146
    • /
    • 2007
  • This study was conducted to determine fertilizer nutrient and pollutant production of Holstein dairy cattle by estimating manure characteristics. The moisture content of feces was 83.9% and 95.1% for urine. The pH of feces and urine were in the ranges of 7.0~7.4 and 7.5~7.8, respectively. The average BOD5, COD, SS, T-N, T-P concentrations of the dairy feces were 18,294, 52,765, 102,889, 2,575, and 457mg/ℓ, respectively. Dairy urine showed lower levels of BOD5(5,455mg/ℓ), COD(8,089mg/ℓ), SS(593mg/ℓ), T-N(3,401mg/l), and T-P(13mg/ℓ) than feces. The total daily produced pollutant amounts of a dairy cow were 924.1g(Milking cow), 538.8g(Dry cow), 284.4g(Heifer) of BOD5, 2,336.5g (Milking cow), 1,651.8g(Dry cow), 734.1g(Heifer) of COD and 4,210.1g(Milking cow), 2,417.1g(Dry cow), 1,629.1g(Heifer) of SS and 194.8g(Milking cow), 96.4g(Dry cow), 58.3g(Heifer) of T-N and 24.0g(Milking cow), 10.2g(Dry cow), 6.1g(Heifer) of T-P. The calculated amount of pollutants produced by a 450kg dairy cow for one year were 181.3kg of BOD5, 492.5kg of COD, 899.9kg of SS, 36.0kg of T-N and 4.1kg of T-P. The total yearly estimated pollutant production from all head(497,261) of dairy cattle in Korea is 90,149 tons of BOD5, 244,890 tons of COD, 447,491 tons of SS, 17,898 tons of T-N and 2,008 tons of T-P. The fertilizer nutrient concentrations of dairy feces was 0.26% N, 0.1% P2O5 and 0.14% K2O. Urine was found to contain 0.34% N, 0.003% of P2O5 and 0.31% K2O. The total daily fertilizer nutrients produced by dairy cattle were 197.4g (Milking cow), 97.4g(Dry cow), and 57.9g(Heifer) of Nitrogen, 54.2g(Milking cow), 22.2g(Dry cow), and 14.2g(Heifer) of P2O5 and 110.8g(Milking cow), 80.4g (Dry cow), and 39.5g(Heifer) of K2O. The total yearly estimated fertilizer nutrient produced by a 450kg dairy animal is 36.2kg of N, 8.8kg of P2O5, 24.6kg of K2O. The estimated yearly fertilizer nutrient production from all dairy cattle in Korea is 18,000 tons of N, 4,397 tons of P2O5, 12,206 tons of K2O. Dairy manure contains useful trace minerals for crops, such as CaO and MgO, which are contained in similar levels to commercial compost being sold in the domestic market. Concentrations of harmful trace minerals, such as As, Cd, Hg, Pb, Cr, Cu, Ni, Zn, met the Korea compost standard regulations, with some of these minerals being in undetected amounts.

The Evaluation of Radiation Dose to Embryo/Fetus and the Design of Shielding in the Treatment of Brain Tumors (임산부의 전뇌 방사선 치료에 있어서의 태아의 방사선량 측정 및 차폐 구조의 설계)

  • Cho, Woong;Huh, Soon-Nyung;Chie, Eui-Kyu;Ha, Sung-Whan;Park, Yang-Gyun;Park, Jong-Min;Park, Suk-Won
    • Journal of Radiation Protection and Research
    • /
    • v.31 no.4
    • /
    • pp.203-210
    • /
    • 2006
  • Purpose : To estimate the dose to the embryo/fetus of a pregnant patient with brain tumors, and to design an shielding device to keep the embryo/fetus dose under acceptable levels Materials and Methods : A shielding wall with the dimension of 1.55 m height, 0.9 m width, and 30 m thickness is fabricated with 4 trolleys under the wall. It is placed between a Patient and the treatment head of a linear accelerator to attenuate the leakage radiation effectively from the treatment head, and is placed 1 cm below the lower margin of the treatment field in order to minimize the dose to a patient from the treatment head. An anti-patient scattering neck supporters with 2 cm thick Cerrobend metal is designed to minimize the scattered radiation from the treatment fields, and it is divided into 2 section. They are installed around the patient neck by attach from right and left sides. A shielding bridge for anti-room scattered radiation is utilized to place 2 sheets of 3 mm lead plates above the abdomen to setup three detectors under the lead sheets. Humanoid phantom is irradiated with the same treatment parameters, and with and without shielding devices using TLD, and ionization chambers with and without a build-up cap. Results : The dose to the embryo/fetus without shielding was 3.20, 3.21, 1.44, 0.90 cGy at off-field distances of 30, 40, 50, and 60 cm. With shielding, the dose to embryo/fetus was reduced to 0.88, 0.60, 0.35, 0.25 cGy, and the ratio of the shielding effect varied from 70% to 80%. TLD results were 1.8, 1.2, 0.8, 1.2, and 0.8 cGy. The dose measured by the survey meter was 10.9 mR/h at the patient's surface of abdomen. The dose to the embryo/fetus was estimated to be about 1 cGy during the entire treatment. Conclusion : According to the AAPM Report No 50 regarding the dose limit of the embryo/fetus during the pregnancy, the dose to the embryo/fetus with little risk is less than 5 cGy. Our measurements satisfy the recommended values. Our shielding technique was proven to be acceptable.

Effects of Formaldehyde/Urea Molar Ratio on Bonding Strength of Plywood and Properties of Sliver-PB and Strand-PB (F/U 몰비의 변이가 합판의 접착성과 Sliver-PB, Strand-PB의 물성에 미치는 영향)

  • Park, Heon;You, Young-Sam
    • Journal of the Korean Wood Science and Technology
    • /
    • v.27 no.2
    • /
    • pp.38-45
    • /
    • 1999
  • This study was to figure out proper Formaldehyde/Urea molar ratio of UF resin with satisfactory bonding strength of plywood and properties of particleboard. The six kinds of UF resins were manufactured with F/U molar ratio 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0. The boards were made of three kinds of raw materials : Veneer, Sliver-Particle and Strand-Particle. Manufacturing condition of plywood : amount of mixing resin was 150g/$m^2$. The fourty secs/mm simple-pressing schedule in the pressure 10kgf/$m^2$ was applied for 480mm${\times}$700mm board at the temperature of $110^{\circ}C$ in a hot press. Manufacturing condition of particleboard : Target density was 0.65g/$cm^2$. The stepwise 9 minutes- multi-pressing schedule in the maximum pressure 40kgf/$cm^2$, the minimum pressure 15kgf/$cm^2$ was applied for $480mm{\times}634mm{\times}12mm$ board at the temperature of $150^{\circ}C$ in a hot press. The results are as follows : I. In bonding strength, plywood which was made by F/U molar ratio 1.2 showed the highest value. Other molar ratio resin also gave the satisfied value of KS standard, 7.5kgf/$cm^2$. 2. In internal bond strength of particleboard, Sliver-Particleboard(SLPB) and Strand-Particleboard(STPB) varied respectively from 5.9kgf/$cm^2$ to 4.8kgf/$cm^2$, from 6.7kgf/$cm^2$ to 5.4kgf/$cm^2$. SLPB with F/U=1.2 and STPB with F/U=1.6 had higher IB value. Also, both SLPB and STPB showed lower IB value in F/U molar ratio 2.0 and 1.0. 3. SLPB and STPB with six kinds of UF resin respectively satisfied bending strength of KS standard 150 Type(130kgf/$cm^2$) and 200 Type(180kgf/$cm^2$). Bending strength data for both of SLPB and STPB showed little or no loss from F/U=1.8 to F/U=1.2. Also, STPB was approximately two times higher than that of SLPB. Therefore, the raw material's shape had more effect on bending strength than the FlU molar ratio. 4. F/U=1.6 and 1.4 showed the lower thickness swelling in SLPB and STPB. All of STPBs satisfied thickness swelling of KS standard, under 12%.

  • PDF

The Analysis of the School Foodservice Employees' Knowledge and Performance Degree of HACCP System in Jeju (제주지역 학교급식 조리종사자의 HACCP 관련 지식 및 수행도 분석)

  • Song, Im-Sook;Chae, In-Sook
    • Journal of Nutrition and Health
    • /
    • v.41 no.8
    • /
    • pp.870-886
    • /
    • 2008
  • The purposes of this study were to (a) analyze school foodservice employees' knowledge and performance degree of HACCP system and (b) provide the basic data for planning the strategies which can be performed for systematic HACCP system in school foodservice. For these purposes, the subjects included 91 dieticians (a response rate 98.9%) and 270 foodservice employees (a response rate 98.2%) at school in Jeju city and they were surveyed from October 21 to November 4, 2006. The data were analyzed by descriptive analysis, reliability analysis, t-test, ANOVA (Duncan multiple range test) and Pearson's correlation coefficients using the SPSS Win Program (version 12.0). In terms of the number of training practice, the result of sanitary training indicated that the dieticians who trained the employees more than once per a week (48.6%) or everyday (36.3%) were 84.7%. And the dieticians who were higher age, full-time job, and working at middle school implemented significantly more training the employees. In the training methods, 40.7% of dieticians used the oral presentation and 37.4 % utilized the printed matters. Also, most of employees (98.1%) have experienced for the training, 39.6% of them did not have regular training experience and 40.7% of them responded that they were understanding the HACCP system well. The result of employees' knowledge level of HACCP system reported that the items of the personal hygiene scored the highest (92.3 points) whereas the items of CCP3 scored the lowest (58.3 points) as the average being 84.2 points (out of 100 scale). In terms of the performance degree of HACCP system, the average was 4.40 (out of 5 scale), the items of the personal hygiene scored the highest as 4.51 whereas the items of CCP2 scored the lowest as 4.31 points. The dieticians' perception degree of employees' performance degree in HACCP system showed that the average was 4.13 (out of 5 scale), so it was significantly lower than actual performance degree as average 4.40 (out of 5 scale). Additionally the employees' knowledge level was positively correlated to performance degree and employees' knowledge level of CCP3, CCP4, and the personal hygiene significantly influenced to the HACCP performance degree. Finally, the dieticians have to recognize correctly the employees' performance degree and on the basis of it must plan the sanitary training which has a proper contents and methods to enhance the employees' knowledge level and achieve more systematic HACCP system in school foodservice.

A Study on Improvement on National Legislation for Sustainable Progress of Space Development Project (우주개발사업의 지속발전을 위한 국내입법의 개선방향에 관한 연구)

  • Lee, Kang-Bin
    • The Korean Journal of Air & Space Law and Policy
    • /
    • v.25 no.1
    • /
    • pp.97-158
    • /
    • 2010
  • The purpose of this paper is to research on the contents and improvement of national legislations relating to space development in Korea to make the sustainable progress of space development project in Korea. Korea has launched its first satellite KITST-1 in 1992. The National Space Committee has established "The Space Development Promotion Basic Plan" in 2007. The plan addressed the development of total 13 satellites by 2010 and the space launch vehicle by 2020, and the launch of moon exploration spaceship by 2021. Korea has built the space center at Oinarodo, Goheng Province in June 2009. In Korea the first small launch vehicle KSLV-1 was launched at the Naro Space Center in August 2009, and its second launch was made in June 2010. The United Nations has adopted five treaties relating to the development of outer space as follows : The Outer Space Treaty of 1967, the Rescue and Return Agreement of 1968, the Liability Convention of 1972, the Registration Convention of 1974, and the Moon Treaty of 1979. All five treaties has come into force. Korea has ratified the Outer Space Treaty, the Rescue and Return Agreement, the Liability Convention and the Registration Convention excepting the Moon Treaty. Most of development countries have enacted the national legislation relating to the development of our space as follows : The National Aeronautic and Space Act of 1958 and the Commercial Space Act of 1998 in the United States, Outer Space Act of 1986 in England, Establishment Act of National Space Center of 1961 in France, Canadian Space Agency Act of 1990 in Canada, Space Basic Act of 2008 in Japan, and Law on Space Activity of 1993 in Russia. There are currently three national legislations relating to space development in Korea as follows : Aerospace Industry Development Promotion Act of 1987, Outer Space Development Promotion Act of 2005, Outer Space Damage Compensation Act of 2008. The Ministry of Knowledge Economy of Korea has announced the Full Amendment Draft of Aerospace Industry Development Promotion Act in December 2009, and it's main contents are as follows : (1) Changing the title of Act into Aerospace Industry Promotion Act, (2) Newly regulating the definition of air flight test place, etc., (3) Establishment of aerospace industry basic plan, establishment of aerospace industry committee, (4) Project for promoting aerospace industry, (5) Exploration development, international joint development, (6) Cooperative research development, (7) Mutual benefit project, (8) Project for furthering basis of aerospace industry, (9) Activating cluster of aerospace industry, (10) Designation of air flight test place, etc., (11) Abolishing the designation and assistance of specific enterprise, (12) Abolishing the inspection of performance and quality. The Outer Space Development Promotion Act should be revised with regard to the following matters : (1) Overlapping problem in legal system between the Outer Space Development Promotion Act and the Aerospace industry Development promotion Act, (2) Distribution and adjustment problem of the national research development budget for space development between National Space Committee and National Science Technology Committee, (3) Consideration and preservation of environment in space development, (4) Taking the legal action and maintaining the legal system for policy and regulation relating to space development. The Outer Space Damage Compensation Act should be revised with regard to the following matters : (1) Definition of space damage and indirect damage, (2) Currency unit of limit of compensation liability, (3) Joint liability and compensation claim right of launching person of space object, (4) Establishment of Space Damage Compensation Council. In Korea, it will be possible to make a space tourism in 2013, and it is planned to introduce and operate a manned spaceship in 2013. Therefore, it is necessary to develop the policy relating to the promotion of commercial space transportation industry. Also it is necessary to make the proper maintenance of the current Aviation Law and space development-related laws and regulations for the promotion of space transportation industry in Korea.

  • PDF

The Effect of Pleural Thickening on the Impairment of Pulmonary Function in Asbestos Exposed Workers (석면취급 근로자에서 늑막비후가 폐기능에 미치는 영향)

  • Kim, Jee-Won;Ahn, Hyeong-Sook;Kim, Kyung-Ah;Lim, Young;Yun, Im-Goung
    • Tuberculosis and Respiratory Diseases
    • /
    • v.42 no.6
    • /
    • pp.923-933
    • /
    • 1995
  • Background: Pleural abnormality is the the most common respiratory change caused by asbestos dust inhalation and also develop other asbestos related disease after cessation of asbestos exposure. So we conducted epidemiologic study to investigate if the pleural abnormality is associated with pulmonary function change and what factors are influenced on pulmonary function impairment. Methods: Two hundred and twenty two asbestos workers from 9 industries using asbestos in Korea were selected to measure the concentration of sectional asbestos fiber. Ouestionnaire, chest X-ray, PFT were also performed. All the data were analyzed by student t-test and chi-square test using SAS. Regressional analysis was performed to evaluate important factors, for example smoking, exposure concentration, period and the existence of pleural thickening, affecting to the change of pulmonary function. Results: 1) All nine industries except two, airborn asbestos fiber concentration was less than an average permissible concentration. PFT was performed on 222 workers and the percentage of male was 88.3%, their mean age was $41{\pm}9$ years old, and the duration of asbestos exposure was $10.6{\pm}7.8$ yrs. 2) The chest X-ray showed normal(89.19%), pulmonary Tb(inactive)(2.7%), pleral thickening (7.66%), suspected reticulonodular shadow(0.9%). 3) The mean values of height, smoking status, concentration of asbestos fiberwere not different between the subjects with pleural thickening and others, but age, cumulative pack-years, the duration of asbestos exposure were higher in subjects with pleural thickening. 4) All the PFT indices were lower in the subjects with pleural thickening than in the subjects without pleural thickening. 5) Simple regression analysis showed there was a significant correlation between $FEF_{75}$ which is sensitive in small airway obstruction and cumulative smoking pack-years, the duration of asbestos exposure and the concentration of asbestos fiber. 6) Multiple regression analysis showed all the pulmonary function indices were decreased as the increase of cumulative smoking pack-years and especially in the indices those are sensitive in small airway obstruction. Pleural thickening was associated with reduction in FVC, $FEV_1$, PEFR and $FEF_{25}$. Conclusion: The more concentration of asbestos fiber and the more duration of asbestos exposure, the greater reduction in $FEF_{50}$, $FEF_{75}$. Therefore PFT was important in the evaluation of early detection for small airway obstruction. Furthermore pleural thickening without asbesto-related parenchymal lung disease is associated with reduction in pulmonary function.

  • PDF

A Study on Developing a VKOSPI Forecasting Model via GARCH Class Models for Intelligent Volatility Trading Systems (지능형 변동성트레이딩시스템개발을 위한 GARCH 모형을 통한 VKOSPI 예측모형 개발에 관한 연구)

  • Kim, Sun-Woong
    • Journal of Intelligence and Information Systems
    • /
    • v.16 no.2
    • /
    • pp.19-32
    • /
    • 2010
  • Volatility plays a central role in both academic and practical applications, especially in pricing financial derivative products and trading volatility strategies. This study presents a novel mechanism based on generalized autoregressive conditional heteroskedasticity (GARCH) models that is able to enhance the performance of intelligent volatility trading systems by predicting Korean stock market volatility more accurately. In particular, we embedded the concept of the volatility asymmetry documented widely in the literature into our model. The newly developed Korean stock market volatility index of KOSPI 200, VKOSPI, is used as a volatility proxy. It is the price of a linear portfolio of the KOSPI 200 index options and measures the effect of the expectations of dealers and option traders on stock market volatility for 30 calendar days. The KOSPI 200 index options market started in 1997 and has become the most actively traded market in the world. Its trading volume is more than 10 million contracts a day and records the highest of all the stock index option markets. Therefore, analyzing the VKOSPI has great importance in understanding volatility inherent in option prices and can afford some trading ideas for futures and option dealers. Use of the VKOSPI as volatility proxy avoids statistical estimation problems associated with other measures of volatility since the VKOSPI is model-free expected volatility of market participants calculated directly from the transacted option prices. This study estimates the symmetric and asymmetric GARCH models for the KOSPI 200 index from January 2003 to December 2006 by the maximum likelihood procedure. Asymmetric GARCH models include GJR-GARCH model of Glosten, Jagannathan and Runke, exponential GARCH model of Nelson and power autoregressive conditional heteroskedasticity (ARCH) of Ding, Granger and Engle. Symmetric GARCH model indicates basic GARCH (1, 1). Tomorrow's forecasted value and change direction of stock market volatility are obtained by recursive GARCH specifications from January 2007 to December 2009 and are compared with the VKOSPI. Empirical results indicate that negative unanticipated returns increase volatility more than positive return shocks of equal magnitude decrease volatility, indicating the existence of volatility asymmetry in the Korean stock market. The point value and change direction of tomorrow VKOSPI are estimated and forecasted by GARCH models. Volatility trading system is developed using the forecasted change direction of the VKOSPI, that is, if tomorrow VKOSPI is expected to rise, a long straddle or strangle position is established. A short straddle or strangle position is taken if VKOSPI is expected to fall tomorrow. Total profit is calculated as the cumulative sum of the VKOSPI percentage change. If forecasted direction is correct, the absolute value of the VKOSPI percentage changes is added to trading profit. It is subtracted from the trading profit if forecasted direction is not correct. For the in-sample period, the power ARCH model best fits in a statistical metric, Mean Squared Prediction Error (MSPE), and the exponential GARCH model shows the highest Mean Correct Prediction (MCP). The power ARCH model best fits also for the out-of-sample period and provides the highest probability for the VKOSPI change direction tomorrow. Generally, the power ARCH model shows the best fit for the VKOSPI. All the GARCH models provide trading profits for volatility trading system and the exponential GARCH model shows the best performance, annual profit of 197.56%, during the in-sample period. The GARCH models present trading profits during the out-of-sample period except for the exponential GARCH model. During the out-of-sample period, the power ARCH model shows the largest annual trading profit of 38%. The volatility clustering and asymmetry found in this research are the reflection of volatility non-linearity. This further suggests that combining the asymmetric GARCH models and artificial neural networks can significantly enhance the performance of the suggested volatility trading system, since artificial neural networks have been shown to effectively model nonlinear relationships.

Intelligent Brand Positioning Visualization System Based on Web Search Traffic Information : Focusing on Tablet PC (웹검색 트래픽 정보를 활용한 지능형 브랜드 포지셔닝 시스템 : 태블릿 PC 사례를 중심으로)

  • Jun, Seung-Pyo;Park, Do-Hyung
    • Journal of Intelligence and Information Systems
    • /
    • v.19 no.3
    • /
    • pp.93-111
    • /
    • 2013
  • As Internet and information technology (IT) continues to develop and evolve, the issue of big data has emerged at the foreground of scholarly and industrial attention. Big data is generally defined as data that exceed the range that can be collected, stored, managed and analyzed by existing conventional information systems and it also refers to the new technologies designed to effectively extract values from such data. With the widespread dissemination of IT systems, continual efforts have been made in various fields of industry such as R&D, manufacturing, and finance to collect and analyze immense quantities of data in order to extract meaningful information and to use this information to solve various problems. Since IT has converged with various industries in many aspects, digital data are now being generated at a remarkably accelerating rate while developments in state-of-the-art technology have led to continual enhancements in system performance. The types of big data that are currently receiving the most attention include information available within companies, such as information on consumer characteristics, information on purchase records, logistics information and log information indicating the usage of products and services by consumers, as well as information accumulated outside companies, such as information on the web search traffic of online users, social network information, and patent information. Among these various types of big data, web searches performed by online users constitute one of the most effective and important sources of information for marketing purposes because consumers search for information on the internet in order to make efficient and rational choices. Recently, Google has provided public access to its information on the web search traffic of online users through a service named Google Trends. Research that uses this web search traffic information to analyze the information search behavior of online users is now receiving much attention in academia and in fields of industry. Studies using web search traffic information can be broadly classified into two fields. The first field consists of empirical demonstrations that show how web search information can be used to forecast social phenomena, the purchasing power of consumers, the outcomes of political elections, etc. The other field focuses on using web search traffic information to observe consumer behavior, identifying the attributes of a product that consumers regard as important or tracking changes on consumers' expectations, for example, but relatively less research has been completed in this field. In particular, to the extent of our knowledge, hardly any studies related to brands have yet attempted to use web search traffic information to analyze the factors that influence consumers' purchasing activities. This study aims to demonstrate that consumers' web search traffic information can be used to derive the relations among brands and the relations between an individual brand and product attributes. When consumers input their search words on the web, they may use a single keyword for the search, but they also often input multiple keywords to seek related information (this is referred to as simultaneous searching). A consumer performs a simultaneous search either to simultaneously compare two product brands to obtain information on their similarities and differences, or to acquire more in-depth information about a specific attribute in a specific brand. Web search traffic information shows that the quantity of simultaneous searches using certain keywords increases when the relation is closer in the consumer's mind and it will be possible to derive the relations between each of the keywords by collecting this relational data and subjecting it to network analysis. Accordingly, this study proposes a method of analyzing how brands are positioned by consumers and what relationships exist between product attributes and an individual brand, using simultaneous search traffic information. It also presents case studies demonstrating the actual application of this method, with a focus on tablets, belonging to innovative product groups.