• Title/Summary/Keyword: Long-term Dependence

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A Study on the Efficiency of KTB Forward Markets (국채선도금리(Forward rate)의 효율성(Efficiency)에 관한 연구)

  • Moon, Gyu-Hyun;Hong, Chung-Hyo
    • The Korean Journal of Financial Management
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    • v.22 no.2
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    • pp.189-212
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    • 2005
  • This study examines the interactions between KTB spot and futures markets using the daily prices from March 4, 2002 to January 31, 2005. We use Granger causality test, impulse Response Analysis and Variance Decomposition through vector autoregressive analysis (VAR). However, considering the long-term relationships between the level variables of KTB spot and futures, we introduced Vector Error Correction Model. The main results are as follows. According to the results of Granger-causality test and impulse response analysis, we find that the yields of KTB forward have a great influence on the change of KTB spot but not vice versa. In terms of volatility analysis, there is no inter-dependence between KTB forward and spot markets. In the variance decomposition analysis we find that the short-term KTB forward has much more impact on the KTB spot market than the long-term KTB forward does. We think these results are meaningful for bond investors who are in charge of capital asset pricing valuation, risk management and international portfolio management.

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A New Organic Modifiers for Anti-Stiction (부착방지를 위한 새로운 표면 개질 물질)

  • Kim, Bong-Hwan;Chun, Kuk-Jin;Lee, Yoon-Sik
    • Journal of Sensor Science and Technology
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    • v.11 no.2
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    • pp.102-110
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    • 2002
  • The chemical and mechanical characteristics of a new surface modifier, dichlorodimethysilane (DDMS, $(CH_3)_3SiCl_2$), for stiction-free polysilicon surfaces are reported. The main strategy is to replace the conventional monoalkyltrichlorosilane(MTS, $RSiCl_3$) such as octadecyltrichlorosilane (ODTS) or 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) with dialkyldichlorosilane (DDS, $R_2SiCl_2$) with twit short chains, especially DDMS. DDMS, with shorter chains in aprotic media, rapidly deposits on the chemically oxidized polysilicon surface at room temperature and successfully prevents long cantilevers of 3 mm in length from in-use as well as release stiction. DDMS-modified polysilicon surfaces exhibit satisfactory hydrophobicity, long term stability and thermal stability, which are comparable to those of FDTS. DDMS as an alternative to FDTS and ODTS provides a few valuable advantages; ease in handling and long-term storage in solution, low temperature-dependence and low cost. In addition to the new modifier molecule, the simplified process of direct release right after washing the modified surface with isooctane was proposed to cut the processing time.

Financial Market Prediction and Improving the Performance Based on Large-scale Exogenous Variables and Deep Neural Networks (대규모 외생 변수 및 Deep Neural Network 기반 금융 시장 예측 및 성능 향상)

  • Cheon, Sung Gil;Lee, Ju Hong;Choi, Bum Ghi;Song, Jae Won
    • Smart Media Journal
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    • v.9 no.4
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    • pp.26-35
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    • 2020
  • Attempts to predict future stock prices have been studied steadily since the past. However, unlike general time-series data, financial time-series data has various obstacles to making predictions such as non-stationarity, long-term dependence, and non-linearity. In addition, variables of a wide range of data have limitations in the selection by humans, and the model should be able to automatically extract variables well. In this paper, we propose a 'sliding time step normalization' method that can normalize non-stationary data and LSTM autoencoder to compress variables from all variables. and 'moving transfer learning', which divides periods and performs transfer learning. In addition, the experiment shows that the performance is superior when using as many variables as possible through the neural network rather than using only 100 major financial variables and by using 'sliding time step normalization' to normalize the non-stationarity of data in all sections, it is shown to be effective in improving performance. 'moving transfer learning' shows that it is effective in improving the performance in long test intervals by evaluating the performance of the model and performing transfer learning in the test interval for each step.

Glass Dissolution Rates From MCC-1 and Flow-Through Tests

  • Jeong, Seung-Young
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2004.06a
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    • pp.257-258
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    • 2004
  • The dose from radionuclides released from high-level radioactive waste (HLW) glasses as they corrode must be taken into account when assessing the performance of a disposal system. In the performance assessment (PA) calculations conducted for the proposed Yucca Mountain, Nevada, disposal system, the release of radionuclides is conservatively assumed to occur at the same rate the glass matrix dissolves. A simple model was developed to calculate the glass dissolution rate of HLW glasses in these PA calculations [1]. For the PA calculations that were conducted for Site Recommendation, it was necessary to identify ranges of parameter values that bounded the dissolution rates of the wide range of HLW glass compositions that will be disposed. The values and ranges of the model parameters for the pH and temperature dependencies were extracted from the results of SPFT, static leach tests, and Soxhlet tests available in the literature. Static leach tests were conducted with a range of glass compositions to measure values for the glass composition parameter. The glass dissolution rate depends on temperature, pH, and the compositions of the glass and solution, The dissolution rate is calculated using Eq. 1: $rate{\;}={\;}k_{o}10^{(ph){\eta})}{\cdot}e^{(-Ea/RT)}{\cdot}(1-Q/K){\;}+{\;}k_{long}$ where $k_{0},\;{\eta}$ and Eaare the parameters for glass composition, pH, $\eta$ and temperature dependence, respectively, and R is the gas constant. The term (1-Q/K) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_{0},\;{\eta}\;and\;E_{a}$ are the parameters for glass composition, pH, and temperature dependence, respectively, and R is the gas constant. The term (1-Q/C) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_0$, and Ea are determined under test conditions where the value of Q is maintained near zero, so that the value of the affinity term remains near 1. The dissolution rate under conditions in which the value of the affinity term is near 1 is referred to as the forward rate. This is the highest dissolution rate that can occur at a particular pH and temperature. The value of the parameter K is determined from experiments in which the value of the ion activity product approaches the value of K. This results in a decrease in the value of the affinity term and the dissolution rate. The highly dilute solutions required to measure the forward rate and extract values for $k_0$, $\eta$, and Ea can be maintained by conducting dynamic tests in which the test solution is removed from the reaction cell and replaced with fresh solution. In the single-pass flow-through (PFT) test method, this is done by continuously pumping the test solution through the reaction cell. Alternatively, static tests can be conducted with sufficient solution volume that the solution concentrations of dissolved glass components do not increase significantly during the test. Both the SPFT and static tests can ve conducted for a wide range of pH values and temperatures. Both static and SPFt tests have short-comings. the SPFT test requires analysis of several solutions (typically 6-10) at each of several flow rates to determine the glass dissolution rate at each pH and temperature. As will be shown, the rate measured in an SPFt test depends on the solution flow rate. The solutions in static tests will eventually become concentrated enough to affect the dissolution rate. In both the SPFt and static test methods. a compromise is required between the need to minimize the effects of dissolved components on the dissolution rate and the need to attain solution concentrations that are high enough to analyze. In the paper, we compare the results of static leach tests and SPFT tests conducted with simple 5-component glass to confirm the equivalence of SPFT tests and static tests conducted with pH buffer solutions. Tests were conducted over the range pH values that are most relevant for waste glass disssolution in a disposal system. The glass and temperature used in the tests were selected to allow direct comparison with SPFT tests conducted previously. The ability to measure parameter values with more than one test method and an understanding of how the rate measured in each test is affected by various test parameters provides added confidence to the measured values. The dissolution rate of a simple 5-component glass was measured at pH values of 6.2, 8.3, and 9.6 and $70^{\circ}C$ using static tests and single-pass flow-through (SPFT) tests. Similar rates were measured with the two methods. However, the measured rates are about 10X higher than the rates measured previously for a glass having the same composition using an SPFT test method. Differences are attributed to effects of the solution flow rate on the glass dissolution reate and how the specific surface area of crushed glass is estimated. This comparison indicates the need to standardize the SPFT test procedure.

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Effect on Smoking Quit Rate of Telling Smokers their Health Risk Appraisal in Terms of Health Age: A Randomized Control Trial

  • Paek, Yu-Jin;Lee, Sungkyu;Kim, Yun-Hee;Lee, Kang-Sook;Yim, Hyeon-Woo;Kim, Myung-Shig;Kim, Cheol-Hwan;Jeung, Ok
    • Asian Pacific Journal of Cancer Prevention
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    • v.15 no.12
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    • pp.4963-4968
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    • 2014
  • Background: We evaluated whether providing health risk appraisal for Koreans (KHRA) in terms of 'health age' during smoking cessation program would effectively help smokers quit smoking or not. Materials and Methods: A total of 332 male smokers aged between 30-65 years old, registered for a smoking cessation program in a public health center in a city, were recruited and underwent a baseline survey from January 2010 to February 2011. They were then prospectively randomized to a conventional counseling group (n=165) or a KHRA group (n=167), and received conventional counseling or KHRA-based counseling for six months. Abstinence rates were identified through carbon monoxide measurement (at the $4^{th}$ and $24^{th}$ weeks) or urinary cotinine level (at the $12^th$ week). Results: The abstinence rate confirmed by exhaled carbon monoxide was significantly higher in the KHRA group (61.1%) than the control group (49.1%) at the $4^{th}$ week (absolute difference 12.0%, 95% CI: 1.4%-22.6%). However, there was no difference in abstinence rates between the two groups at the 12th and 24th weeks. The predicting factors of 24 week's smoking cessation success were age, older than 50 years old (OR 2.02, 95% CI: 1.16-3.52), lower Fagerstr$\ddot{o}$m Test for Nicotine Dependence score less than 4 (OR 1.84, 95% CI: 1.03-3.29), and higher Self Efficacy/Temptation score (OR 1.79, 95% CI: 1.05-3.06). Conclusions: Smoking cessation counseling with KHRA could be effective compared to conventional counseling in the short period of smoking cessation. Further study is needed to evaluate the long-term efficacy of KHRA in tobacco dependence treatment and to establish the indication and target population of this tool.

Open Clinical Trial of Morning Light Therapy in Sleep Disturbance of Alcohol Dependent Patients (알코올의존 환자에서의 수면장애에 대한 아침 광치료의 임상시도)

  • Ko, Young-Hoon;Joe, Sook-Haeng;Jeon, Seung-Kyu;Kim, Byoung-Kyu;Kwon, Sung-Min
    • Korean Journal of Psychosomatic Medicine
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    • v.11 no.2
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    • pp.196-204
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    • 2003
  • Objectives: It is known that sedative hypnotics would make cross tolerance with alcohol and deteriorate quality of sleep in alcoholics. Light therapy is effective non-pharmacological intervention for sleep disturbance in circadian phase disorders, jet-lag, shift-work and age-related sleep disorders. Authors would investigate the effects of morning light therapy on sleep of patients with alcohol dependence during recovery state without withdrawal symptoms. Methods: 13 patients with alcohol dependence who have not any alcohol withdrawal symptom were recruited. Light therapy during 1 hour in the morning had been administered by 2500 Lux light box through serial 3 days. Sleep state of subjects were assessed by sleep log and the subjective satisfaction at sleep was by 100 mm visual analogue scale. Sleepiness, depressive mood, anxiety were evaluated by 100mm visual analogue scale at 8 AM, 2 PM and 8 PM. For assessment of performance ability that would be associated with sleepiness and vigilance, trail making test A, B and digit symbol substitution test were performed by two times on base line and 4th day. Univariate repeated-measures ANOVAs were performed for each measures except performance tests which were analysed by paired t-test. Results: Sleep latency and sleep efficiency were significantly improved with light therapy and satisfaction at sleep was. There was no significant difference in sleepiness at 2 PM with light therapy but sleepiness at 8 AM significantly decreased and at 8 PM increased. The time to complete Trail making test and digit symbol substitution test were significantly shortened at 4th day compared with baseline. Fatigue at 8 AM were not significantly changed with light therapy but at 2 PM and 8 PM significantly decreased. Depressive mood and anxiety were not significantly changed with light therapy. Conclusion: Although this study had some limitations, it showed that light therapy would be effective modality on sleep disturbance of patients with alcohol dependence who have recovered from alcohol withdrawal symptoms. It is proposed that short term light therapy could be used clinically for alcoholics with insomnia. In the future, long term controlled studies using more objective tools for sleep are required to further investigate the effect of light therapy in alcoholics.

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Decision-Tree Model of Long-term Abstention from Smoking: Focused on Coping Styles (장기적 금연 지속기간 예측 모형: 스트레스 대처를 중심으로)

  • Suh, Kyung-Hyun;You, Jae-Min
    • Korean Journal of Health Education and Promotion
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    • v.22 no.4
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    • pp.73-90
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    • 2005
  • Objectives: Smokers who had failed to quit smoking were frequently reported that life stress mostly interrupted their abstention. Stress vulnerability model for smoking cessation has been considered, and most of contemporary smoking cessation programs help smokers develop coping strategies for stressful situations. This study aims to investigate the appropriate coping styles for stress of abstention from smoking. The result of investigating the relationship between abstention following smoking cessation program and coping styles would suggest useful information for those who want to stop smoking and health practitioners who help them. Methods: Participants were 69 smokers (62 males, 7 females) participated in a hospitalized smoking cessation program, whose mean age was 44.89 (SD=9.61). Participants took medical test and completed questionnaires and psychological tests including: Fagerstrom Test for Nicotine Dependence and Multidimensional Coping Scale. To identify participants' abstention, researchers followed them for 2 years. To identify whether abstained or not and encourage them to abstain, researchers called them on the telephone once a week for 3 months. After 3 months, they were contacted every other week till 6 months passed since they left smoking cessation program. And they were contacted once a month for other 18months. Researchers also contacted their family to identify their abstention. Data Mining Decision Tree was performed with 37 variables (13 variables for the coping styles and 24 smoking-related variables) by Answer Tree 3.0v Results: Forty four (63.8%) out of sixty nine for 2 weeks, 34 (49.3%) for 6 months, 25 (36.2%) abstained for 1 year, and 22 (31.9%) abstained for 2 years. Participants of this study abstained average of 286.77 days from smoking. Included variables of a Decision Tree model for this study were positive interpretation, emotional expression, self-criticism, restraint and emotional social support seeking. Decision Tree model showed that those (n=9) who did not interpret positively (<=7.5) and criticized themselves (>6.5) abstained 23 days only, while those (n=9) who interpreted positively (>7.5), expressed their emotion freely (>6.5), and sought social support actively (>11.5) abstained 730 days, till last day of the investigation. Conclusion: The results of this study showed that certain coping styles such as positive interpretation, emotional expression, self-criticism, restraint and emotional social support seeking were important factors for long-term abstention from smoking. These findings reiterate the role of stress for abstention from smoking and suggest a model of coping styles for successful abstention from smoking. Despite of limitation of this study, it might help smokers who want to stop smoking and health practitioners who help them.

A Study on the Stationary State of Military Pension using Markov Chains (마코프 체인을 이용한 군인연금 안정상태에 관한 연구)

  • Bae, Young-Min
    • Journal of Digital Convergence
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    • v.19 no.2
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    • pp.61-69
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    • 2021
  • The military pension deficit is increasing due to an increase in the average life expectancy and pension option rate, and a significant reason for this is estimated to be a continued increase in the number of military pension recipients. In terms of the soundness of military pension finances, this paper uses the Markov chain model to validate the stability of the military group, suggesting the direction of future military pension system in terms of the ratio of pension receipts to employees, and verifying the feasibility of the method applied through verification. Through this paper, we have confirmed that the initial 45,270 military personnel converge to 43,141 after a certain period of time and reach a stable state, which is expected to help us to estimate the long term size of military pension recipients to confirm the direction of national financial support. Military man who are eligible for pensions for more than 20 years have a relatively low rate of turnover or retirement compared to ordinary private groups, making it easier to define their status and simplify state transition probabilities. Therefore, it is expected that the sustainability of the military pension will be confirmed from a long term perspective by viewing the military group as a system and applying it to the Markov chain model by checking the probability of transfer of status such as promotion, maintaining the current grade, and retirement during the period.

A Data-driven Classifier for Motion Detection of Soldiers on the Battlefield using Recurrent Architectures and Hyperparameter Optimization (순환 아키텍쳐 및 하이퍼파라미터 최적화를 이용한 데이터 기반 군사 동작 판별 알고리즘)

  • Joonho Kim;Geonju Chae;Jaemin Park;Kyeong-Won Park
    • Journal of Intelligence and Information Systems
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    • v.29 no.1
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    • pp.107-119
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    • 2023
  • The technology that recognizes a soldier's motion and movement status has recently attracted large attention as a combination of wearable technology and artificial intelligence, which is expected to upend the paradigm of troop management. The accuracy of state determination should be maintained at a high-end level to make sure of the expected vital functions both in a training situation; an evaluation and solution provision for each individual's motion, and in a combat situation; overall enhancement in managing troops. However, when input data is given as a timer series or sequence, existing feedforward networks would show overt limitations in maximizing classification performance. Since human behavior data (3-axis accelerations and 3-axis angular velocities) handled for military motion recognition requires the process of analyzing its time-dependent characteristics, this study proposes a high-performance data-driven classifier which utilizes the long-short term memory to identify the order dependence of acquired data, learning to classify eight representative military operations (Sitting, Standing, Walking, Running, Ascending, Descending, Low Crawl, and High Crawl). Since the accuracy is highly dependent on a network's learning conditions and variables, manual adjustment may neither be cost-effective nor guarantee optimal results during learning. Therefore, in this study, we optimized hyperparameters using Bayesian optimization for maximized generalization performance. As a result, the final architecture could reduce the error rate by 62.56% compared to the existing network with a similar number of learnable parameters, with the final accuracy of 98.39% for various military operations.

A Study on the Export Competitiveness of Korea IT Industry to China (한국 IT산업의 대중국 수출경쟁력 분석에 관한 연구)

  • Jeong, Boon-Do;Yun, Bong-Ju
    • International Commerce and Information Review
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    • v.11 no.4
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    • pp.111-128
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    • 2009
  • As it is expected that change in trade environment has a significant impact on Korean economic growth as well as foreign trade of Korean economy we need an appropriate political response to it. Therefore, this study aims to analyse the Export Competitiveness of IT Industry to China and our trade policy. Korean balance of trade to China in 2007 records surplus of 18.9 billion dollars. However, many experts estimate unfavorable balance of trade will appear from 2010. In consideration of this condition, this study suggests a desirable trade policy for long-term maintenance of current Export Competitiveness between Korea and China. Using TSI and RCA, it analyses a Export Competitiveness of IT Industry to China from 2003 to 2007. To sum up the results, the TSI has been declining since 2005. RCA of semi-conductors has been declining since 2005 while that of communication equipment and computers has been increasing. During the analysis period, the mean RCA of semi-conductors is 55.01, which indicates that its export advantage is somewhat weak, and the mean RCA of communication equipment and computers are 227.22 and 175.83 respectively, which indicates that their export advantage is very strong. Production and export of Korea IT industry have greatly increased in quantity, but its technological quality and diversity have not been satisfactory. In particular, the base of IT industry is growing weaker due to serious dependence of core spare parts on advanced countries and transfer of simple assembly plants to China. To maintain export competitiveness of IT industry, we should pay more attention to technological improvement through more investment to the original technology for local production of core spare parts.

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