• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.2
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• pp.95-115
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• 2013

In traditional inventory models, purchase prices of raw materials are assumed to be fixed and have no effect on the optimal choice of inventory policies. However, when purchase prices fluctuate continuously over time, inventory costs are heavily affected by purchasing prices. Risk-averse inventory model decides order quantity and ordering time by considering not just purchase prices but also the risk from the discrepancy between estimated prices and realized prices. In this paper, we propose a myopic inventory policy which incorporates price risk into deciding ordering time and quantities. While the existing risk-averse model has no mechanism to reallocate inventories already purchased for a specific future period, the revised one reallocates initial inventories of each period to other future periods so that it can avoid purchasing raw materials at high prices. Experimental results demonstrate that the revised model outperforms the existing one in respect of total cost and variability.

• Journal of the Korean Data and Information Science Society
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• v.13 no.2
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• pp.195-200
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• 2002

We consider the Bernoulli two-armed bandit problem. It is well known that the my optic strategy is optimal when the prior distribution is concentrated at two points in the unit square. We investigate several cases in the unit square whether the my optic strategy is optimal or not. In general, the my optic strategy is not optimal when the prior distribution is not concentrated at two points in the unit square.

• Journal of the Korean Society for Railway
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• v.7 no.2
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• pp.71-76
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• 2004

In this paper, we propose a pilot study to deploy the Railway Conflict Detection and Resolution System(RCDRS) in the context of Korean Railway(KORAIL). KORAIL plans to deploy in near future RCDRS, which is a decision support module placed on the top level of the Railway Traffic Management System(RTMS). This study entails the review of the state-of-art researches and projects in the field of the railway traffic management, as well as the analysis of the traffic characteristics of the major railroad lines in KORAIL. The analysis provides a basis to choose a solution approach for the railway conflict detection and resolution problem that each individual line faces. This study plays a role as a pilot study for a full systematic approach, in which interactions between lines require further advanced analysis to take the entire KORAIL lines into consideration rather than a myopic approach.

• Current Optics and Photonics
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• v.3 no.6
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• pp.597-604
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• 2019

This study was performed to evaluate objective visual quality and ocular scattering in myopic refractive-surgery patients, compared to emmetropes. Optical vision-quality parameters (modulation transfer function (MTF) cutoff and Strehl ratio) and objective scattering index (OSI) were measured using an optical quality analysis system (OQAS II) based on the double-pass technique. In all subjects, the higher the MTF cutoff and Strehl ratio, the lower the OSI and ocular higher-order aberrations (HOAs). The MTF cutoff and Strehl ratio for the laser-assisted subepithelial keratectomy (LASEK) group were lower than those for the emmetropia group, while the OSI, ocular HOAs, and spherical aberration (SA) for the LASEK group were higher than those for emmetropia group. Ocular scattering would be one of the important factors in regard to visual quality. Therefore, the quality of the retinal image in the LASEK patients has been shown to reduce the quality of vision more than in the emmetropes.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.4
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• pp.425-432
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• 2008

While the Vendor-Managed Inventory(VMI) is a convenient inventory replenishment policy for the customer company, the supplier usually bears the burden of higher inventory and urgent shipments to avoid shortage. Recently some manufacturers begin to fix the production schedule for the next few days (such as three days). Utilizing that information can improve the efficiency of the VMI. In this study, we present a myopic optimization model using a mixed inter programming; and a heuristics algorithm. We compare the performance of the two proposed methods with the existing (s, S) reorder policy. We consider the total cost as the sum of transportation cost and inventory cost at the customer's site. Numerical tests indicate that the two proposed methods significantly reduce the total cost over the (s, S) policy.

• Journal of the Korean Institute of Educational Facilities
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• v.12 no.2
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• pp.14-22
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• 2005

This study analyzed the remodeling cases of 53 public primary schools located in Seoul to grasp the trends and set the direction in remodeling public primary schools. As a result of the analysis, before the sixth Education Process major remodeling of schools was focused on increasing the number of classrooms and after the sixth Education Process public space was increased. According to development of education, frequency of remodeling is increased. But myopic remodeling works were not a surprise. It means the schools simply focused on increasing space. Therefore, the study aims to set the direction for a comprehensive and systemic remodeling plan which will serve as an opportunity to not only improve physical life of schools but also extend functional life and enhance the quality of educational environment.

• ETRI Journal
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• v.34 no.2
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• pp.272-275
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• 2012

This letter studies the problem of exploiting multichannel diversity in a spectrum sharing system, where the secondary user (SU) sequentially explores channel state information on the licensed channels with time consumption. To maximize the expected achievable throughput for the SU, we formulate this problem as an optimal stopping problem, whose objective is to choose the right channel to stop exploration based on the observed signal-to-noise ratio sequence. Moreover, we propose a myopic but optimal rule, called one-stage look-ahead rule, to solve the stopping problem.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.5
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• pp.309-314
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• 2022

Ophthalmic complications after tooth extraction are rare but discomforting events. This paper reports the rare complications of a 20-year-old male patient who presented with transient blurring of vision after surgical extraction of several teeth under general anesthesia. Additional diagnostic tests were performed to discern the reason for the pseudomyopia. A literature review was carried out by searching for articles published from 1936 to 2019 using the keywords "dental," "ophthalmic," "complication," "blurring of vision," and "accommodation disturbance" in PubMed. Only six patients with detailed ophthalmic symptoms similar to those of our patient have been reported. If blurred vision or a myopic shift in refraction is present, pseudomyopia should be suspected, and cycloplegic refraction is essential for diagnosis. The condition improves spontaneously

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.103-113
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• 1998

Until now, the study of eye refractive error examination for high school students are a few report that in Korea. In particular, there is few report about the visual power for same group during several years. We compared the study of refractive error done this year with that reported three years ago at the same high school. From the these data, the distribution of ammetropia was investigated. The study of refractive error for high school students was also compared with those reported before for the Adults and the middle school student. When the visual power is refered to spherical equivalent, the 36% of the whole students examined above had emmetropia and the other part of them fumed out to be ammetropia which is classify to 60.6% belonged to myopia and 4.4% belonged to hyperpia. The ratio of myopia for this year students is increased in comparision with the students in 1995. The ratio of emmetropia for this year students is 7.4% higher, and the ratio of myopia for this year students is 4% higher, but the ratio of hyperopia is very lower than that for the adults in 1997. In the kind of refractive error, it is classified that a simple myopia is shown to highest ratio as a 28.6% of 1212 eyes examined, a compound myopic astigmatism to the next high ratio as a 22.4%, a simple myopic astigmatism as 14.4%, a simple hyperopic astigmatism as 3.1%, a mixed astigmatism as a 1.7%, a simple astigmatism as 1.2%, a compound hyperopic astigmatism as 1.2%, respectively. The percentage of an astigmatism is a 76.7% of total eyes examined if Cyl-0.25 Dptr is included to an astigmatism. On the other hand, The percentage of an astigmatism is a 45.6% of total eyes examined if Cyl-0.25 Dptr is excluded to an astigmatism. In the kind of astigmatism, the number of students had an astigmatism with the rule is about 4.5 times than that of astigmatism against the rule. From the result of comparision the right eye with the left eye, the right eye of the students had more a myopic refractive error than the left eye, which is same as adults' case, there is no difference in a refractive error between the boy students and the girl students.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.131-138
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• 2000

We compared the study of refractive error of the eyes done in 1998 with that reported three years ago at any high school in the north Kyungki. From the these data, the distribution of ammetropia was investigated. The study of refractive error for high school students was also compared with those reported before for the Adults and the middle school student. When the refractive error is refered to spherical equivalent, the 40.6% of the whole students examined above had emmetropia and the other part of them(59.4%) turned out to be ammetropia which is classified to 46.4% belonged to myopia and 13.0% belonged to hyperpia. The ratio of emmetropia for the students in 1998 is 4.4% lower, and the ratio of hyperopia is 4.3% lower, but the ratio of myopia for the students in 1998 is 8.7% higher than that for the student in 1995. In the kind of refracive error, it is classified that a simple myopia is shown to highest ratio as a 23.6% of 6143 eyes examined, a compound myopic astigmatism to the next high ratio as a 17.4%, a simple myopic astigmatism as 10.9%, a simple hyperopic astigmatism as 9.8%, a simple astigmatism as 7.1%, a compound hyperopic astigmatism as 2.2%, a mixed astigmatism as a 1.8%, respectively. The percentage of an astigmatism is a 69.6% of total eyes examined if Cyl-0.25 Dptr is included to an astigmatism. On the other hand. The percentage of an astigmatism is a 45.0% of total eyes examined if Cyl-0.25 Dptr is excluded to an astigmatism. In the kind of astigmatism, the number of students had an astigmatism with the rule is about 5.6 times than that of astigmatism against the rule. From the result of comparison the right eye with the left eye, the right eye of the students had more a myopic refractive error than the left eye, which is same as adults' case.