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Expiration-Day Effects: The Korean Evidence (주가지수 선물과 옵션의 만기일이 주식시장에 미치는 영향: 개별 종목 분석을 중심으로)

  • Choe, Hyuk;Eom, Yun-Sung
    • The Korean Journal of Financial Management
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    • v.24 no.2
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    • pp.41-79
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    • 2007
  • This study examines the expiration-day effects of stock index futures and options in the Korean stock market. The so-called 'expiration-day effects', which are the abnormal stock price movements on derivatives expiration days, arise mainly from cash settlement. Index arbitragers have to bear the risk of their positions unless they liquidate their index stocks on the expiration day. If many arbitragers execute large buy or sell orders on the expiration day, abnormal trading volumes are likely to be observed. If a lot of arbitragers unwind positions in the same direction, temporary trading imbalances induce abnormal stock market volatility. By contrast, if some information arrives at market, the abnormal trading activity must be considered a normal process of price discovery. Stoll and Whaley(1987) investigated the aggregate price and volume effects of the S&P 500 index on the expiration day. In a related study, Stoll and Whaley(1990) found a similarity between the price behavior of stocks that are subject to program trading and of the stocks that are not. Thus far, there have been few studies about the expiration-day effects in the Korean stock market. While previous Korean studies use the KOSPI 200 index data, we analyze the price and trading volume behavior of individual stocks as well as the index. Analyzing individual stocks is important for two reasons. First, stock index is a market average. Consequently, it cannot reflect the behavior of many individual stocks. For example, if the expiration-day effects are mainly related to a specific group, it cannot be said that the expiration of derivatives itself destabilizes the stock market. Analyzing individual stocks enables us to investigate the scope of the expiration-day effects. Second, we can find the relationship between the firm characteristics and the expiration-day effects. For example, if the expiration-day effects exist in large stocks not belonging to the KOSPI 200 index, program trading may not be related to the expiration-day effects. The examination of individual stocks has led us to the cause of the expiration-day effects. Using the intraday data during the period May 3, 1996 through December 30, 2003, we first examine the price and volume effects of the KOSPI 200 and NON-KOSPI 200 index following the Stoll and Whaley(1987) methodology. We calculate the NON-KOSPI 200 index by using the returns and market capitalization of the KOSPI and KOSPI 200 index. In individual stocks, we divide KOSPI 200 stocks by size into three groups and match NON-KOSPI 200 stocks with KOSPI 200 stocks having the closest firm characteristics. We compare KOSPI 200 stocks with NON-KOSPI 200 stocks. To test whether the expiration-day effects are related to order imbalances or new information, we check price reversals on the next day. Finally, we perform a cross-sectional regression analysis to elaborate on the impact of the firm characteristics on price reversals. The main results seem to support the expiration-day effects, especially on stock index futures expiration days. The price behavior of stocks that are subject to program trading is shown to have price effects, abnormal return volatility, and large volumes during the last half hour of trading on the expiration day. Return reversals are also found in the KOSPI 200 index and stocks. However, there is no evidence of abnormal trading volume, or price reversals in the NON-KOSPI 200 index and stocks. The expiration-day effects are proportional to the size of stocks and the nearness to the settlement time. Since program trading is often said to be concentrated in high capitalization stocks, these results imply that the expiration-day effects seem to be associated with program trading and the settlement price determination procedure. In summary, the expiration-day effects in the Korean stock market do not exist in all stocks, but in large capitalization stocks belonging to the KOSPI 200 index. Additionally, the expiration-day effects in the Korean stock market are generally due, not to information, but to trading imbalances.

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Occupation-based Occupational Therapy for an Youth With Sensory Integrative Dysfunction - A Single Case Study (감각통합기능장애를 가진 청소년의 작업수행에 초점을 맞춘 작업치료 사례)

  • Ji, Seok-Yeon;Lee, Kyoung-Min;Kim, Mi-Sun
    • The Journal of Korean Academy of Sensory Integration
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    • v.6 no.1
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    • pp.47-62
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    • 2008
  • Introduction : Sensory Integration(SI) theory, science it is developed by an occupational therapist A. Jean Ayres, is the one of the most popular frames of reference used in occupational therapy(OT) intervention. It has been proved as a scientific theory especially in neuroscience discipline through abundant research and practice. Occupational therapists apply the SI therapy with strong clinical reasoning to improve adaptive behaviors of their clients and try to link the adaptive behaviors with occupational performance in the clients' everyday life. One of the manners regarding clinical reasoning is Top-down approach. In occupational therapy discipline, Top-down approach is well-reflected within two evaluation tools; Canadian Occupational Performance Measure(COPM) and Assessment of Motor and Process Skills(AMPS) and two models of practice; Canadian Model of Occupational Performance(CMOP) and Occupational therapy intervention process model(OTIPM). Objective : The purpose of this paper demonstrates how SI therapy can be employed within OTIPM and how the OT process (evaluation-intervention-outcome) can be structuralized based on the Top-down approach. This single-case study recognizes the impact of a SI therapy for a male adolescent on his occupational performance. Intervention Examined : "P" was 16 years old male adolescent with no diagnosis and junior of the high school when he was referred. P was always with mouth opened, showed difficulties in gathering things need to be prepared and managing and paying money for shopping, and his colleges dislike getting close to him because he can't was his body well. AMPS was administrated in initial evaluation and reevaluation of P's occupation performance, Bruininks-Oserestky Test of Motor Proficiency-2(BOT-2) was carried out to assess motor functions and perception skills related in sensory integration, and occupational therapist performed clinical observation in order to complement the evaluation quantitatively and quantitatively. Based on the evaluation, it is concluded that the SI therapy is primary means to improve P's occupational performance, and three therapeutic approaches were constructed; restorative, acquired and compensatory approach. P showed improved motor and process skills in occupational performance after undergone the occupational therapy. Conclusions : The sensory integration therapy was practical enough to build the bridge between the occupational performance(Top) and the underlying component problems (Bottom). The OTIPM was helpful to identify meaningful occupation for P and P's family within P's contexts, and the AMPS was valuable to analyze and clarify the cause of difficulties in the chosen occupational performance.

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Elementary School Students' Amounts of Sugar, Sodium, and Fats Exposure through Intake of Processed Food (초등학생의 주요 가공식품으로부터 섭취하는 당, 나트륨, 지방류 등의 노출실태 조사 연구)

  • Kang, Moon-Hee;Yoon, Ki-Sun
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.38 no.1
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    • pp.52-61
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    • 2009
  • The purpose of this study was to investigate the extent of excessive sugar, sodium, cholesterol, and saturated fat consumptions by elementary school students through processed food's intake. A survey study was conducted with 384 fourth and sixth grade students and their mothers from two schools in Seoul and Gyeonggi province. The data were analyzed for the frequency analysis, chi-square test and Pearson correlation using the SPSS/Windows (ver. 15.0). Results showed that students consumed high amounts of sugars through processed milk and carbonated beverages, and yogurt. Additionally, they had high sodium and saturated fat levels in their diet through Ramen. There was significant correlation (p<0.01) between mothers' purchasing and students' intake of processed food. Overall, both students and mothers had some knowledge on the impact of sodium on human health. About 50 percent of the respondents did not have accurate information about cholesterol, saturated fat, and trans fat. More than 50 percent of students and mothers had no nutritional education on the risk of excessive intake of sugar, sodium, cholesterol, saturated fat, and trans fat. Top twenty percent of the students had 39.7 g of sugar, 940.1 mg of sodium, 17.8 mg of cholesterol, and 11.2 g of saturated fat through processed foods per day on the average. These results suggest that execution of nutritional education about processed food is needed for high risk group of elementary school students and their mothers. Moreover, government must enact the regulation and policy for the food industry to reduce the risky nutrients from children's favorite processed food.

Impact of Adjuvant Chemoradiation Therapy on the Postoperative 5-year Survival Rates for Stage-II Gastric Cancer (2기 위암환자의 수술 후 보조 항암요법 및 방사선 치료가 생존율에 미치는 영향)

  • Hong, Seong-Kweon;Choi, Min-Gew;Baik, Yong-Hae;Noh, Jae-Hyung;Sohn, Tae-Sung;Kim, Sung
    • Journal of Gastric Cancer
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    • v.5 no.4 s.20
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    • pp.281-287
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    • 2005
  • Purpose: This study was conducted to evaluate the effectiveness and the role of post-operative adjuvant chemoradiation therapy in a stage-II (UICC, 1997) primary gastric cancer. Materials and Methods: From September 1994 to December 2004, 954 stage-II gastric-cancer patients were seen, and all of them underwent a curative resection with extensive (D2) lymph-node dissection. The chemotherapy consisted of fluorouracil $(400mg/m^2)$ plus leucovorin $(20mg/m^2)$ for 5 days, followed by 4,500 cGy of radiotherapy for 5 weeks with fluorourcil and leucovorin on the first 4 days and the last 3 days of radiotherapy. Two five-day cycles of chemotherapy were given four weeks after the completion of radiotherapy. The Kaplan-Meier method was used to estimate the survival rates. To assess the importance of potential prognostic factors, we performed univariate and multivariate analyses using a log-rank test and Cox's proportional hazards regression model. A P value <0.05 was considered significant. Results: Univariate analysis revealed that age, tumor size, gross type, surgical method, and postoperative adjuvant therapy had statistical significance. Among these factors, age, surgical method, tumor size, surgical method, and postoperative adjuvant therapy were found to be independent prognostic factors by using a multivariate analysis. The postoperative adjuvant chemotherapy group and the chemoradiation therapy group had survival benefit compared to the surgery-only group. However the chemoradiation therapy group had no significant survival benefit compared to the chemotherapy group. Conclusion: The postoperative adjuvant therapy in stage-II gastric-cancer patients had significant benefit. Therefore, postoperative adjuvant chemoradiation therapy has an acceptable effect. A large-scale, randomized study is needed to evaluate the effectiveness and the role of postoperative radiation therapy.

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Quality Dimensions Affecting the Effectiveness of a Semantic-Web Search Engine (검색 효과성에 영향을 미치는 시맨틱웹 검색시스템 품질요인에 관한 연구)

  • Han, Dong-Il;Hong, Il-Yoo
    • Asia pacific journal of information systems
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    • v.19 no.1
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    • pp.1-31
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    • 2009
  • This paper empirically examines factors that potentially influence the success of a Web-based semantic search engine. A research model has been proposed that shows the impact of quality-related factors upon the effectiveness of a semantic search engine, based on DeLone and McLean's(2003) information systems success model. An empirical study has been conducted to test hypotheses formulated around the research model, and statistical methods were applied to analyze gathered data and draw conclusions. Implications for academics and practitioners are offered based on the findings of the study. The proposed model includes three quality dimensions of a Web-based semantic search engine-namely, information quality, system quality and service quality. These three dimensions each have measures designed to collectively assess the respective dimension. The model is intended to examine the relationship between measures of these quality dimensions and measures of two dependent constructs, including individuals' net benefit and user satisfaction. Individuals' net benefit was measured by the extent to which the user's information needs were adequately met, whereas user satisfaction was measured by a combination of the perceived satisfaction with search results and the perceived satisfaction with the overall system. A total of 23 hypotheses have been formulated around the model, and a questionnaire survey has been conducted using a functional semantic search website created by KT and Hakia, so as to collect data to validate the model. Copies of a questionnaire form were handed out in person to 160 research associates and employees working in the area of designing and developing semantic search engines. Those who received the form, 148 respondents returned valid responses. The survey form asked respondents to use the given website to answer questions concerning the system. The results of the empirical study have indicated that, of the three quality dimensions, information quality was found to have the strongest association with the effectiveness of a Web-based semantic search engine. This finding is consistent with the observation in the literature that the aspects of the information quality should serve as a basis for evaluating the search outcomes from a semantic search engine. Measures under the information quality dimension that have a positive effect on informational gratification and user satisfaction were found to be recall and currency. Under the system quality dimension, response time and interactivity, were positively related to informational gratification. On the other hand, only one measure under the service quality dimension, reliability was found to have a positive relationship with user satisfaction. The results were based on the seven hypotheses that have been accepted. One may wonder why 15 out of the 23 hypotheses have been rejected and question the theoretical soundness of the model. However, the correlations between independent variables and dependent variables came out to be fairly high. This suggests that the structural equation model yielded results inconsistent with those of coefficient analysis, because the structural equation model intends to examine the relationship among independent variables as well as the relationship between independent variables and dependent variables. The findings offer some useful implications for owners of a semantic search engine, as far as the design and maintenance of the website is concerned. First, the system should be designed to respond to the user's query as fast as possible. Also it should be designed to support the search process by recommending, revising, and choosing a search query, so as to maximize users' interactions with the system. Second, the system should present search results with maximum recall and currency to effectively meet the users' expectations. Third, it should be capable of providing online services in a reliable and trustworthy manner. Finally, effective increase in user satisfaction requires the improvement of quality factors associated with a semantic search engine, which would in turn help increase the informational gratification for users. The proposed model can serve as a useful framework for measuring the success of a Web-based semantic search engine. Applying the search engine success framework to the measurement of search engine effectiveness has the potential to provide an outline of what areas of a semantic search engine needs improvement, in order to better meet information needs of users. Further research will be needed to make this idea a reality.

Comparative Volume Measuring Methods According to the Tumor Characters in PET/CT (PET/CT 검사에서 종양의 특성에 따른 체적 측정 방법 비교)

  • Choi, Yong Hoon;Ban, Yung Gak;Oh, Shin Hyun;Lim, Han Sang;Kim, Jae Sam
    • The Korean Journal of Nuclear Medicine Technology
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    • v.20 no.1
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    • pp.52-58
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    • 2016
  • Purpose Recent retrospective studies are being actively conducted to analyze the survival of patients with SUVmax, MTV, TLG, such as information from a variety of PET originating. However, there is no clear way is difficult to accurately measure the volume of the tumor may be the difference between the caster is raised. In this study, to evaluate compare the volume measuring methods according to the characteristics of the tumor. Materials and Methods 18F-saline to fill the NEMA IEC Body Phantom insert the volume of balance and imbalance in phantom were acquired to the Biograph truepoint 40 (Siemens medical system, Germany) PET/CT scanner. The ratio of the volume and Background was acquired as 3.0, 5.0, 8.0, 18, 40. Clinical patients were randomly selected 120 people in staging patients with cancer of the digestive system from the year 2010 until the year 2014. Measurement methods were used a 40% threshold, 50% threshold and gradient segmentation technique, i.e. PET EDGE. Five years of experience of the two radio-technologist and one doctor was measured by repeated three times. Analysis methods were Intraclass correlation coefficient and Pearson correlation. Results In Phantoms, the 40% threshold method gave the best concordance between measured and actual volumes (r = 0.992, 0.997). In clinical patient outcome agreement between observers EDGE it is as high as 0.999 (CI: 0.998-0.999). And there were no statistical significance of the difference between the measurements (P = 0.620). 40% threshold method showed the best correlation between the measurements (r = 0.953). Increasing the ratio of tumor to background decreased the influence of a measuring method. Conclusion How to measure volume of the tumor in the patient was clinically most useful is 50% and the lowest impact on the characteristics of the tumor. Therefore, to reduce the background of the patients in PET/CT scan, it should be required research and effort.

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OD matrix estimation using link use proportion sample data as additional information (표본링크이용비를 추가정보로 이용한 OD 행렬 추정)

  • 백승걸;김현명;신동호
    • Journal of Korean Society of Transportation
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    • v.20 no.4
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    • pp.83-93
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    • 2002
  • To improve the performance of estimation, the research that uses additional information addition to traffic count and target OD with additional survey cost have been studied. The purpose of this paper is to improve the performance of OD estimation by reducing the feasible solutions with cost-efficiently additional information addition to traffic counts and target OD. For this purpose, we Propose the OD estimation method with sample link use proportion as additional information. That is, we obtain the relationship between OD trip and link flow from sample link use proportion that is high reliable information with roadside survey, not from the traffic assignment of target OD. Therefore, this paper proposes OD estimation algorithm in which the conservation of link flow rule under the path-based non-equilibrium traffic assignment concept. Numerical result with test network shows that it is possible to improve the performance of OD estimation where the precision of additional data is low, since sample link use Proportion represented the information showing the relationship between OD trip and link flow. And this method shows the robust performance of estimation where traffic count or OD trip be changed, since this method did not largely affected by the error of target OD and the one of traffic count. In addition to, we also propose that we must set the level of data precision by considering the level of other information precision, because "precision problem between information" is generated when we use additional information like sample link use proportion etc. And we Propose that the method using traffic count as basic information must obtain the link flow to certain level in order to high the applicability of additional information. Finally, we propose that additional information on link have a optimal counting location problem. Expecially by Precision of information side it is possible that optimal survey location problem of sample link use proportion have a much impact on the performance of OD estimation rather than optimal counting location problem of link flow.

Intelligent Optimal Route Planning Based on Context Awareness (상황인식 기반 지능형 최적 경로계획)

  • Lee, Hyun-Jung;Chang, Yong-Sik
    • Asia pacific journal of information systems
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    • v.19 no.2
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    • pp.117-137
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    • 2009
  • Recently, intelligent traffic information systems have enabled people to forecast traffic conditions before hitting the road. These convenient systems operate on the basis of data reflecting current road and traffic conditions as well as distance-based data between locations. Thanks to the rapid development of ubiquitous computing, tremendous context data have become readily available making vehicle route planning easier than ever. Previous research in relation to optimization of vehicle route planning merely focused on finding the optimal distance between locations. Contexts reflecting the road and traffic conditions were then not seriously treated as a way to resolve the optimal routing problems based on distance-based route planning, because this kind of information does not have much significant impact on traffic routing until a a complex traffic situation arises. Further, it was also not easy to take into full account the traffic contexts for resolving optimal routing problems because predicting the dynamic traffic situations was regarded a daunting task. However, with rapid increase in traffic complexity the importance of developing contexts reflecting data related to moving costs has emerged. Hence, this research proposes a framework designed to resolve an optimal route planning problem by taking full account of additional moving cost such as road traffic cost and weather cost, among others. Recent technological development particularly in the ubiquitous computing environment has facilitated the collection of such data. This framework is based on the contexts of time, traffic, and environment, which addresses the following issues. First, we clarify and classify the diverse contexts that affect a vehicle's velocity and estimates the optimization of moving cost based on dynamic programming that accounts for the context cost according to the variance of contexts. Second, the velocity reduction rate is applied to find the optimal route (shortest path) using the context data on the current traffic condition. The velocity reduction rate infers to the degree of possible velocity including moving vehicles' considerable road and traffic contexts, indicating the statistical or experimental data. Knowledge generated in this papercan be referenced by several organizations which deal with road and traffic data. Third, in experimentation, we evaluate the effectiveness of the proposed context-based optimal route (shortest path) between locations by comparing it to the previously used distance-based shortest path. A vehicles' optimal route might change due to its diverse velocity caused by unexpected but potential dynamic situations depending on the road condition. This study includes such context variables as 'road congestion', 'work', 'accident', and 'weather' which can alter the traffic condition. The contexts can affect moving vehicle's velocity on the road. Since these context variables except for 'weather' are related to road conditions, relevant data were provided by the Korea Expressway Corporation. The 'weather'-related data were attained from the Korea Meteorological Administration. The aware contexts are classified contexts causing reduction of vehicles' velocity which determines the velocity reduction rate. To find the optimal route (shortest path), we introduced the velocity reduction rate in the context for calculating a vehicle's velocity reflecting composite contexts when one event synchronizes with another. We then proposed a context-based optimal route (shortest path) algorithm based on the dynamic programming. The algorithm is composed of three steps. In the first initialization step, departure and destination locations are given, and the path step is initialized as 0. In the second step, moving costs including composite contexts into account between locations on path are estimated using the velocity reduction rate by context as increasing path steps. In the third step, the optimal route (shortest path) is retrieved through back-tracking. In the provided research model, we designed a framework to account for context awareness, moving cost estimation (taking both composite and single contexts into account), and optimal route (shortest path) algorithm (based on dynamic programming). Through illustrative experimentation using the Wilcoxon signed rank test, we proved that context-based route planning is much more effective than distance-based route planning., In addition, we found that the optimal solution (shortest paths) through the distance-based route planning might not be optimized in real situation because road condition is very dynamic and unpredictable while affecting most vehicles' moving costs. For further study, while more information is needed for a more accurate estimation of moving vehicles' costs, this study still stands viable in the applications to reduce moving costs by effective route planning. For instance, it could be applied to deliverers' decision making to enhance their decision satisfaction when they meet unpredictable dynamic situations in moving vehicles on the road. Overall, we conclude that taking into account the contexts as a part of costs is a meaningful and sensible approach to in resolving the optimal route problem.

Tertiary Cytoreduction for Recurrent Epithelial Ovarian Cancer: a Multicenter Study in Turkey

  • Arvas, Macit;Salihoglu, Yavuz;Sal, Veysel;Gungor, Tayfun;Sozen, Hamdullah;Kahramanoglu, Ilker;Topuz, Samet;Demirkiran, Fuat;Iyibozkurt, Cem;Bese, Tugan;Ozgu, Burcin Salman;Vatansever, Dogan;Tokgozoglu, Nedim;Berkman, Sinan;Turan, Hasan;Bengisu, Ergin;Sofiyeva, Nigar;Demiral, Irem;Meydanli, Mutlu
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.4
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    • pp.1909-1915
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    • 2016
  • Background: The purpose of this study was to determine the benefit of tertiary cytoreductive surgery (TC) for secondary recurrent epithelial ovarian cancer (EOC), focusing on whether optimal cytoreduction has an impact on disease-free survival, and whether certain patient characteristics could identify ideal candidates for TC. Materials and Methods: Retrospective analysis of secondary recurrent EOC patients undergoing TC at three Turkish tertiary institutions from May 1997 to July 2014 was performed. All patients had previously received primary cytoreduction followed by intravenous platinum-based chemotherapy and secondary cytoreduction for first recurrence. Clinical and pathological data were obtained from the patients' medical records. Survival analysis was caried out using the Kaplan Meier method. Actuarial curves were compared by the two tailed Logrank test with a statistical significance level of 0.05. Results: Median age of the patients was 49.6 years (range, 30-67) and thirty-eight (72%) had stage III-IV disease at initial diagnosis. Twenty six (49%) had optimal and 27 (51%) suboptimal cytoreduction during tertiary debulking surgery. Optimal initial cytoreduction, time to first recurrence, optimal secondary cytoreduction, time interval between secondary cytoreduction and secondary recurrence, size of recurrence, disease status at last follow-up were found to be significant risk factors to predict optimal TC. Optimal cytoreduction in initial and tertiary surgery and serum CA-125 level prior to TC were independent prognostic factors on univariate analysis. Conclusions: Our results and a literature review clearly showed that maximal surgical effort should be made in TC, since patients undergoing optimal TC have a better survival. Thus, patients with secondary recurrent EOC in whom optimal cytoreduction can be achieved should be actively selected.

Nutrition Education Effect in Obesity Treatment for Children (소아비만 치료의 임상영양 교육 효과)

  • 김영숙;이순영;김영옥
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.31 no.6
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    • pp.1011-1017
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    • 2002
  • The aim of this study was to investigate nutrition education effect in the long term and short term nutrition education intervention for childhood obesity. Seventy-seven obese children aged seven to twelve who visiting obesity clinic in a university hospital were given nutrition education therapy. Long-term as well as short-term education effect had been measured based on reducing level of Body Mass Index (BMI), Relative Body Weight (RBW) and lipid profile as well as dietary behavior. Identification of factors influencing the effect of nutrition education had been tested using multiple regression analysis as well as Main Whitney test. The result showed that nutrition education intervention had a significant impact on reducing the level of BMI, RBW and lipid profile during long term and short term period. Duration of clinic visit and total number of clinic visit were the most significant factors for the short term effect for obesity treatment. However, frequent clinic visit per month was not significant factor on short term effect. Therefore sustained participation for nutrition education by the obese individual seems more important factors than other factors especially for short term effect. Although, there was the tendency of reducing weight with longer duration and frequent clinic visit, and changing health behavior, none of the factors showed statistically significant effect on the long term effect for the obesity treatment. The results may imply that more complex factors involved for the long term treatment of childhood obesity than short term treatment.