• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.62-70
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• 2000

The design of gear train is a kind of mixed problems which have to determine various types of design variables; i,e., continuous, discrete, and integer variables. Therefore, the most common practice of optimum design using the derivative of objective function has difficulty in solving those kinds of problems and the optimum solution also depends on initial guess because there are many sophisticated constrains. In this study, the Genetic Algorithm is introduced for the optimum design of gear trains to solve such problems and we propose a genetic algorithm based gear design system. This system is applied for the geometrical volume(size) minimization problem of the two-stage gear train and the simple planetary gear train to show that genetic algorithm is better than the conventional algorithm solving the problems that have continuous, discrete, and integer variables. In this system, each design factor such as strength, durability, interference, contact ratio, etc. is considered on the basis of AGMA standards to satisfy the required design specification and the performance with minimizing the geometrical volume(size) of gear trains

• Journal of Society of Preventive Korean Medicine
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• v.4 no.2
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• pp.108-118
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• 2000

According to the North Korean documents , North Korean government have emphasized the development of the Koryo medicine (traditional korean medicine) and encouraged the combination of the Koryo and the modern medicine. It is regarded that this attitude arose from the ruler's will toward independency in the medical field and at the same time the lack of modern medical resources . Combinations of the Koryo medicine and the modern medicine in the clinical textbooks are classified as follows: first, mixed medication of the Koryo and the modern medicine. Second, combination of the traditional acupuncture(or moxibustion) and the medication of modern medicines. Third, injection of modern medicines at acupoints. Forth, an intramuscular or an intravenous injection of the Koryo medicine. Fifth, anesthesia using Koryo medicine. Sixth, simple surgery at the acupoints. Lastly, combination of injection and the traditional therapy(eg. acupuncture, moxibustion and cupping) Despite of many achievements in the field of combined medical treatment, recent economic failure and severe famine for several years caused collapse of the health care delivery system in North Korea, and it is hard to find combined practices actually.

• Journal of the Korean Operations Research and Management Science Society
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• v.41 no.4
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• pp.113-128
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• 2016

This paper proposes a Bi-level Genetic Algorithm for the Fixed Charge Transportation Problem with Non-linear Unit Cost. The problem has the property of mixed integer program with non-linear objective function and linear constraints. The bi-level procedure consists of the upper-GA and the lower-GA. While the upper-GA optimize the connectivity between each supply and demand pair, the lower-GA optimize the amount of transportation between the pairs set to be connected by the upper-GA. In the upper-GA, the feasibility of the connectivity are verified, and if a connectivity is not feasible, it is modified so as to be feasible. In the lower-GA, a simple method is used to obtain a pivot feasible solution under the restriction of the connectivity determined by the upper-GA. The obtained pivot feasible solution is utilized to generate the initial generation of chromosomes. The computational experiment is performed on the selected problems with several non-linear objective functions. The performance of the proposed procedure is analyzed with the result of experiment.

• Journal of the Korean Mathematical Society
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• v.55 no.3
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• pp.623-669
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• 2018

In Donaldson-Thomas theory, moduli spaces are locally the critical locus of a holomorphic function defined on a complex manifold. In this paper, we develop a theory of critical virtual manifolds which are the gluing of critical loci of holomorphic functions. We show that a critical virtual manifold X admits a natural semi-perfect obstruction theory and a virtual fundamental class $[X]^{vir}$ whose degree $DT(X)=deg[X]^{vir}$ is the Euler characteristic ${\chi}_{\nu}$(X) weighted by the Behrend function ${\nu}$. We prove that when the critical virtual manifold is orientable, the local perverse sheaves of vanishing cycles glue to a perverse sheaf P whose hypercohomology has Euler characteristic equal to the Donaldson-Thomas type invariant DT(X). In the companion paper, we proved that a moduli space X of simple sheaves on a Calabi-Yau 3-fold Y is a critical virtual manifold whose perverse sheaf categorifies the Donaldson-Thomas invariant of Y and also gives us a mathematical theory of Gopakumar-Vafa invariants.

• Journal of Chest Surgery
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• v.23 no.5
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• pp.871-880
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• 1990

We clinically evaluated 182 cases of the ventricular septal defect that we experienced at the Department of Thoracic and Cardiovascular Surgery, Maryknoll Hospital from March 1986 through June 1990. Of the 182 cases, 95 patients were male and 87 patients were female. Their age distribution ranged from 8 month to 37 years and their mean age was 8.1 years. The most common chief complaint was frequent upper respiratory infection. Among them, 46 patients had associated cardiac anomalies, which were subdivided as follow; 9 cases of patent foramen ovale, 8 cases of infundibular stenosis, 6 cases of pulmonary valvular stenosis, 4 cases of left superior vena cava, and etc. The most common preoperative abnormal EKG finding was left ventricular hypertrophy in 22 cases. Ninety-three patients[51.1%] underwent simple closure of the VSD and the rest[48.0%] underwent patch closure. In anatomical classification by Kirklin type I constituted 24.2%; type II, 74.8%, type III, 0.7%, and the mixed type of type I and II, 0.5%, The important postoperative EKG changes were noted in 38 cases[20.9%], 18 cases of which were incomplete right bundle branch block. Thirty-three patients[18.1%] developed minor and major complications, and five patients died, overall operative mortality being 2.7%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.242-245
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• 2009

The effect of fuel composition on flame length was studied in a non-premixed turbulent diluted hydrogen jet with coaxial air. The observed flame length was expressed as a function of the ratio of coaxial air to fuel jet velocity and compared with a theoretical prediction based on the velocity ratio. Four cases of fuel mixed by volume were determined. In the present study, we derived a scaling correlation for predicting the flame length in a simple jet with coaxial air using the effective jet diameter in the near-field concept. The experimental results showed that visible flame length had a good relation with the theoretical prediction. The scaling analysis is also valid for diluted hydrogen jet flames with varied fuel composition.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.1
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• pp.91-95
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• 1993

To investigate hemolysin from Vibrio vulnificus in terms of protein chemistry and immunochemistvy, the simple method to produce antiserum was developed as follows ; Crude hemolysin from Vibrio vulnificus was mixed with cholesterol-phosphatidylcholine-liposome. Only hemolysin with molecular weight of 50kD was selertively bound to the liposome. Thus, without purification of crude hemolysin, liposome bound hemolysin was used as antigen to produce antiserum by injecting into back muscle of a rabbit. Resultant antiserum reacted only with hemolysin. Hemouysin of Vibrio vulnificus from patients and environment was formed single band in gel diffusion precipitation reaction with antiserum.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.7
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• pp.589-593
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• 2005

The electronic states of ZnO doped with Al, Ga and In, which belong to III family elements in periodic table, were calculated using the density functional theory. In this study, the calculation was performed by two Programs; the discrete variational Xa (DV-Xa) method, which is a sort of molecular orbital full potential method; Vienna Ab-initio Simulation Package (VASP), which is a sort of pseudo potential method. The fundamental mixed orbital structure in each energy level near the Fermi level was investigated with simple model using DV-Xa. The optimized crystal structures calculated by VASP were compared to the measured structures. The density of state and the energy levels of dopant elements were shown and discussed in association with properties.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.3
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• pp.199-205
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• 2006

Patterned sapphire substrates (PSS) were fabricated by a simple wet etching process with $SiO_2$ stripe masks and a mixed solution of $H_2SO_4$ and $H_3PO_4$. GaN layers were epitaxially grown on the PSS under the optimized 2-step growth condition of metalorganic vapor deposition. During the 1st growth step, GaN layers with triangular cross sections were grown on the selected area of the surface of the PSS, and in the 2nd growth step, the GaN layers were laterally grown and coalesced with neighboring GaN layers. The density of threading dislocations on the surface of the coalesced GaN layer was $2{\sim}4\;{\times}\;10^7\;cm^{-2}$ over the entire region. The epitaxial structure of near-UV light emitting diode (LED) was grown over the GaN layers on the PSS. The internal quantum efficiency and the extraction efficiency of the LED structure grown on the PSS were remarkably increased when compared to the conventional LED structure grown on the flat sapphire substrate. The reduction in TD density and the decrease in the number of times of total internal reflections of the light flux are mainly attributed due to high level of scattering on the PSS.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.314-314
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• 1996

We investigate the scheduling problem for periodic job shops with blocking. We develop Petri net models for periodic job shops with finite buffers. A buffer control method would allow the jobs to enter the input buffer of the next machine in the order for which they are completed. We discuss difficulties in using such a random order buffer control method and random access buffers. We thus propose an alternative buffer control policy that restricts the jobs to enter the input buffer of the next machine in a predetermined order. The buffer control method simplifies job flows and control systems. Further, it requires only a cost-effective simple sequential buffer. We show that the periodic scheduling model with finite buffers using the buffer control policy can be transformed into an equivalent periodic scheduling model with no buffer, which is modeled as a timed marked graph. We characterize the structural properties for deadlock detection. Finally, we develop a mixed integer programming model for the no buffer problem that finds a deadlock-free optimal sequence that minimizes the cycle time.