• Management Science and Financial Engineering
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• v.18 no.2
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• pp.1-4
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• 2012

We study optimal trading strategy of a market maker with stock inventory. Following Avellaneda and Stoikov (2008), we assume the stock price follows a normal distribution. However, we take a constant expected rate of the stock return and assume that the stock volatility is an inverse function of the stock price level. We show that the optimal bid-ask spread of the market maker is wider for a higher expected rate of stock returns.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.21
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• pp.101-110
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• 1990

This study presents a two-level inventory distribution system with one-upper level facility(warehouse) in first echelon and n-lower level facilities(stores) in the second echelon. The demand process at the upper level is induced by the aggregated backorder processes of n independently operated lower level facilities in parallel. For the upper level and the lower level we find the decision points and the distribution function of the aggregate backorders from n-stores. Optimal allocation units and expected system profits are obtained. If the product is of great enough importance to the customer, echelon structure will include a shadow installation. Also, this case is analyzed. Numerical examples are presented to illustrate the results for each case.

• Journal of Korean Academy of Nursing
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• v.34 no.1
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• pp.63-71
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• 2004

Purpose: This study was to identify the influencing factors of the compliance level to a therapeutic regimen after a bone mineral densitometry test. Method: The sample for the study was 95 people who took the bone mineral densitometry test from March, 2002 to July, 2002. Data was collected by mail using aself reporting questionnaire on the selected variables such as the compliance level, self efficacy, health locus of control, susceptibility, severity, usefulness, barrier, and self esteem. Results: The average compliance level was 63.93. Through multiple regression, three independent variables including chance health locus of control on personality, the result of bone mineral density and self-efficacy were entered in the model as the significant determinants of the compliance level after a bone mineral densitometry test. The coefficients of determination of each variable were 10.9%, 8.3% and 8.1% respectively. Conclusion: The identification of the determinants of the compliance level to the therapeutic regimen after bone mineral densitometry is expected to contribute to the development of an intervention program to improve the compliance level to the therapeutic regimen in osteoporosis patients.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.4
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• pp.102-110
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• 2010

The reliability evaluation may be a efficient method for estimating of the quantitative structural safety considering the effect of uncertainties included in high-speed railway bridges. The expected life-cycle cost(LCC) based upon the reliability evaluation will reasonably offer the safety level and design criteria of high-speed railway bridges. Therefore, this study determined the expected life-cycle cost and optimal design method of high-speed railway bridges on the basis of the result of the numerical analysis and reliability evaluation. For this, after creating various design method based upon the standard design of high-speed railway bridges, the numerical analysis is conducted on each of the alternative design methods. The reliability evaluation by the design strength limit state function is conducted considering the effect of external uncertainties on the basis of the numerical analysis result. The expected life-cycle cost of high-speed railway bridges is calculated on the basis of the reliability evaluation result by each of the alternative design methods. Also, the optimal design method is determined using the calculated expected life-cycle cost. In addition, The result of reliability evaluation and expected life-cycle cost of optimal design method are examined considering the effect of internal uncertainties. It is expected that the result of this study can be used as a basic information for the systematic safety evaluation and optimal structure design of high-speed railway bridges.

• Journal of the military operations research society of Korea
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• v.24 no.1
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• pp.176-188
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• 1998

In this paper, it is identified that the optimal level of each performance measures (service and inventory level) is not sensitive to an uncertain environment under JIT Kanban system designed by Moeeni. Moreover, it is proposed that the optimal design method considering multiple performance characteristics is the optimal level decision method according to the relative importance differences of each performance when there exist multiple performance characteristics. The result from the simulation analysis shows that the number of Kanban for stage 3 (final process) and stage 2 is increased at the service level. It is found that the expected loss is minimal when the cycle time decreases and the container size increases. However, the stage 1 is not affected by the number and cycle time of Kanban. It is thus important to consider carefully the cycle time and the container size of the Kanban to satisfy the demand in right time. In case of inventory level, the working inventory level decreases when the container size is decreased and the working inventory level also decreases slightly when the cycle time of the Kankban is increased in stage 1 and 2.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.9
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• pp.740-752
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• 1989

Many works have been reported in various fields on the subject of controlling a robot with high-level robot languages. This paper presents one such effort and explains the development of an automatic robot programming system which utilizes the concept of the task level language. This system is expected to act as an intelligent supporting tool in robot programming and be put into practical use. Emphasis is placed on the role of the programming system as a tool that generates the executable robot program according to the user specified tasks. Several task level commands are used in the developed system, and the resulting inflexibility is complemented by the motion level commands of the motion level robot languages. Thus, the advantages of both task and motion level languages are utilized, and no knowledge of specific language grammer is needed even when using motion level commands. To increase the usability of the developed system, various methods are provided for supplementing the programming system using taught data.

• Journal of Korean Physical Therapy Science
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• v.7 no.1
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• pp.333-352
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• 2000

The objective of this study was to identify the effects of the cognitive performance of stroke patients on their motor function recovery after comprehensive rehabilitation management. The subjects of this study were 41 stroke in-patients of the Rehabilitation Hospital, College of Medicine, Yonsei University, hospitalized during the period from September 1, 1997 to May 5, 1998. The cognitive performance was measured using a Mini-Mental State Examination(MMSE) and the motor function recovery using Motor Assessment Scale(MAS). The data were analyzed by the paired t-test, independent t-test, a one way ANOVA, and Pearson's correlation coefficiency. The findings were as follows: 1. There was a significant difference found in the motor function recovery level after the comprehensive rehabilitation management. 2. There was no significant difference found in relation to sex, age, cause of stroke, laterality of paralysis and the level of spasticity. However, there was a big difference between pre- and post-treatment regarding the treatment period. 3. In line with the cognitive performance level, there was a significant difference found in the motor function recovery level after the comprehensive rehabilitation management. 4. The correlation between the elements of the cognitive performance and the motor recovery was found to be high in orientation, attention, calculation, and language. Those elements were expected to give larger effects on motor recovery after the comprehensive rehabilitation management. Based on this study, the cognitive performance level was found to play an important role in bringing effects on motor recovery after the comprehensive rehabilitation management of stroke patients. And the evaluation on the motor recovery based on quality would be also expected to be examined, as well as the cognitive performance level test accompanied by Intelligence Quality(IQ) test.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.3
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• pp.27-46
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• 1992

This paper considers an (r, Q) policy for operation of a multipurpose facility. It is assumed that whenever the inventory level falls below r, the model starts to produce the fixed amount of Q. The facility can be utilized for extra production during idle periods, that is, when the inventory level is still greater than r right after a main production operation is terminated or an extra production operation is finished. But, whenever the facility is in operation for an extra production, the operation can not be terminated for the main production even though the inventory level falls below r. In the model, the demand for the product is assumed to arrive according to a compound Poisson process and the processing time required to produce a product is assumed to follow an arbitary distribution. Similarly, the orders for the extra production is assumed to accur in a Poisson process are the extra production processing time is assumed to follow an arbitrary distribution. It is further assumed that unsatisfied demands are backordered and the expected comulative amount of demands is less than that of production during each production period. Under a cost structure which includes a setup/ production cost, a linear holding cost, a linear backorder cost, a linear extra production lost sale cost, and a linear extra production profit, an expression for the expected cost per unit time for a given (r, Q) policy is obtained, and using a convex property of the cost function, a procedure to find the optimal (r, Q) policy is presented.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.35
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• pp.41-69
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• 2007

This study analyzes some important implications for the forthcoming revision of eUCP through the methodology of expected utility maximization theory. The overall results are as follows. First, beneficiary with an initial wealth has a risk-averse utility in traditional letter of credit transaction, and he would be more risk-averse in eUCP transaction. Secondly, the beneficiary who has risk-averse utility will pay for the risk premium to reduce the risk of corruption of an electronic record by means of cost of loss reduction activities. Thirdly, the cost of loss reduction activities is represented by a convex cost function, Fourthly, a risk averse beneficiary pursues loss reducing activities to the point where the expected marginal product of loss reduction is less than its marginal cost. Fifthly, a more risk-averse eUCP beneficiary will always select a higher level of loss reduction as long as the effectiveness of loss reduction is certain. Sixthly, when the effectiveness of loss reduction is uncertain, the more risk-averse eUCP beneficiary does not necessarily choose a higher level of loss reducing activities. Finally, it would be more reasonable that eUCP Article 11 should protect eUCP beneficiary who pursues a higher level of loss reducing activities.

• Asia-Pacific Journal of Business
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• v.10 no.2
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• pp.27-41
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• 2019

Following the methodology of Ben-Rephael, Kadan and Wohl (2015), this paper examines whether firm-level liquidity premium exists and whether the premium exhibits a long-term trend in the Korean stock market. The results show that over the whole sample period (1998-2018), a liquidity premium of 0.083% exists in the cross-section of stocks. Interestingly, the pricing of liquidity declines significantly over the sample period. Sub-period analysis indicates that liquidity is priced mainly in the first sub-period (1998-2004) with a significant monthly premium of 0.304%, while the pricing of liquidity becomes weaker or insignificant in the second (2005-2011) and the third (2012-2018) period. I also find that the significance of the liquidity premium in the first period is attributed to small stocks. To explore underlying reasons that might affect the decline in the liquidity premium, I decompose liquidity premium into the product of firm-level liquidity and the sensitivity of expected stock returns on liquidity. The results reveal that the long-term decline is explained by both an increase in firm-level liquidity and a decrease in the sensitivity of expected returns on liquidity.