• Journal of the military operations research society of Korea
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• v.15 no.1
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• pp.14-27
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• 1989

This paper deals with the mission effectiveness of an airfleet, Airfleet operating system consists of a finite number of units performing the several mission types. Earlier works for the mission effectiveness of a fleet is limited to only one mission type and computer simulation approaches. The mission effectiveness. model of a fleet is constructed by three attributes - the mission readiness of the units, the mission reliability and capability of units. The environmental conditions and human factors affecting the mission success are considered together. The solution of the model is obtained by analytical technique. Especially, AOS is considered a closed queueing network with a finite number of units and a single job class. And then, the mission readiness of the units is found by the mean value analysis. The model would be a useful tool to readily evaluate mission effectiveness of a airfleet as it is and provide a criterion for determining the optimal operating policy.

• KIEE International Transactions on Power Engineering
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• v.2A no.4
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• pp.166-173
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• 2002

Dispersed Generation (DG) units significantly effect the existing distribution protection practices. Therefore, new protection practices of the distribution system interconnected with DG units should be reevaluated and developed. In this paper, a new inter-tie protection scheme of DG units for distribution automatic reclosing is proposed. The impact of DG units on existing radial-sectionaliser coordination is analyzed. And the effects of the distribution reclosing type (radial and passive reclosing) on DG dynamics are analyzed and classified. From the results of the DG dynamic responses by the reclosing type, i.e. radial and passive reclosing, the inter-tie protection schemes of DG are introduced to improve the reliability and availability of utility interactive DG. The proposed schemes are proved and evaluated by a case study using PSCAD/EMTDC simulation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.122-128
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• 2011

This paper proposes a new control scheme of lithium ion battery units based on single phase multi-level converter. In the DC/AC converter applications using battery storage system, it is necessary to control the balancing voltage of individual battery units for high efficiency utilization. Using the proposed control scheme, the DC/AC single phase converter system is applied. To verify the effectiveness of the proposed control scheme, computer simulation is accomplished. In the computer simulation, lithium-ion battery units and single phase multi-level converter system are modeled and carried out using Psim simulation program. It will be helpful for design and applications of energy storage system with lithium-ion battery.

• Archives of Pharmacal Research
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• v.26 no.6
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• pp.441-445
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• 2003

New sulfonated amino ribofuranans were synthesized to elucidate the relationship between structure and specific biological activities such as anti-HIV and blood anticoagulant activities. The synthesis was performed by sulfonation of copolymers having various proportion of (1$\rightarrow5)-\alpha$-D-ribofuranosidic unit. The sulfonation with piperidine N-sulfonic acid produced the sulfonated amino ribofuranans in high yield. The anti-HIV activity of sulfonated 3-amino-3-deoxy-(1$\rightarrow5)-\alpha$-D-ribofuranan showed more potent by increasing the degree of sulfonation and the average molecular weights. This activity was almost equal to the activities of sulfonated ribofuranans and ribopyranans reported before in spite of low molecular weight. The blood anticoagulant activities was observed at 36-48 mg/units, more potent than standard dextran sulfonate, 22.7 mg/units. In addition, the blood anticoagulant activities of sulfamide-copolysaccharide consisting various proportion of (1$\rightarrow5)-\alpha$-D-ribofuranan units were potentiated by increasing sulfonated amino-ribofuranan units from 13 to 21 mg/units.

• Journal of the military operations research society of Korea
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• v.23 no.1
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• pp.14-24
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• 1997

This study is to develop an optimal surveillance units assignment model in order to obtain the maximized surveillance efficiency with the limited surveillance units. There are many mathematical models which deal with problems to assign weapons such as aircrafts, missiles and guns to targets. These models minimize the lost required to attack, the threat forecast from the enemy, or both of them. However, a problem of the efficient assignment of surveillance units is not studied yet, nevertbless it is important in the battlefield surveillance system. This paper is concerned with the development of the optimal surveillance units assignment model using integer programming. An optimal integer solution of the model can be obtained by using linear programming and branch and bound method.

• Kyungpook Mathematical Journal
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• v.62 no.2
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• pp.213-227
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• 2022

We discuss the relation between units and nilpotents of a ring, concentrating on the transitivity of units on nilpotents under regular group actions. We first prove that for a ring R, if U(R) is right transitive on N(R), then Köthe's conjecture holds for R, where U(R) and N(R) are the group of all units and the set of all nilpotents in R, respectively. A ring is called right UN-transitive if it satisfies this transitivity, as a generalization, a ring is called unilpotent-IFP if aU(R) ⊆ N(R) for all a ∈ N(R). We study the structures of right UN-transitive and unilpotent-IFP rings in relation to radicals, NI rings, unit-IFP rings, matrix rings and polynomial rings.

• Earthquakes and Structures
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• v.22 no.5
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• pp.475-485
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• 2022

This paper presents a comparative experimental study on structural behavior of the interlocking masonry walls under in-plane cyclic loading. The main purpose of this study is to increase lateral load-bearing capacities of masonry walls by using interlocking units. The interlocking units were designed by considering failure modes of masonry walls and produced using lightweight foamed concrete. To this end, three masonry walls which are hollow, fully grouted, and reinforced were constructed with interlocking units. Also, a traditional masonry brick wall was built for comparison reasons. The walls were tested under in-plane cyclic loading. Then, structural parameters of the walls such as lateral load bearing and total energy dissipation capacities, ductility, stiffness degradation as well as failure modes obtained from the tests were compared with each other. The results have shown that the walls with the interlocking units have better structural performance than traditional masonry brick walls and they may be used in the construction of low-rise masonry structures in rural areas to improve in-plane structural performance.

• Journal of Korean Association for Spatial Structures
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• v.7 no.3 s.25
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• pp.125-132
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• 2007

The purpose of this study is to investigate the functions and formations of the component units as aesthetic components in the spatial grid. The main subject covered here is the presentation of the morphological method of shaping spatial grid by application of 3-dimensional units satisfying the suitable form of polyhedra, tensegrity and hybrid structure. In accordance with the subject, the definition of the spatial grid and 3-dimensional nit, the relationship between them, and then the functions of those units are reviewed. And the formations of polyhedral units, tensegrity units and hybrid units are generated by means of the modules of the simplest type or pattern. And also the overall appearance of the spatial grid shaped by several basic methods in which one unit can be joined to another and arranged are depicted.

• Journal of Korean Academy of Nursing
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• v.29 no.2
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• pp.346-360
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• 1999

The purpose of this research was to identify nursing interventions performed by hospital nurses in Korea. The sample consisted of 311 nurses working in three hospitals. The Nursing Interventions Use Questionnaire developed by the Iowa Intervention Project team was used for data collection. The instrument was translated to Korean using the method of back-translation. Eighteen interventions were performed at least daily. Interventions in the Physiological : Basic domain were most frequently used at least daily. No interventions in the Family and Behavioral domains were used by nurses at least once a day. The most frequently used interventions was Documentation, followed by the interventions Medication : Parenteral, Intravenous(IV) Insertion, Temperature Control, and Shift Report. The intervention performed least often was Reproductive Technology Management. Nurses working in intensive care units on the whole performed interventions most often, while nurses working in obstetric, gynecological, and pediatric units performed them least often. The nurses working in intensive care unit, medical and surgical care units performed the interventions in the Physiological : Basic domain more often than the nurses working in obstetric, gynecological, and pediatric units. The nurses working in obstetric, gynecological, and pediatric units used the interventions in the Family domain more often than the nurses working in the other three units. This study contributes to the documentation of nursrs' work in Korea. Further study will be needed to validate nursing activities of each NIC intervention.

• Journal of Korean Society for Quality Management
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• v.43 no.1
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• pp.31-42
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• 2015

Purpose: System consists of a lot of units with coherent function. In design phase, various units could be considered with the same function. In this study, we consider the alternative units with the same function and redundancy allocation to maximize system reliability in multi level system. Methods: The redundancy allocation problem with the alternative units in multi level system is formulated. Memetic algorithm(MA) is proposed to optimize the redundancy allocation problem. In addition, the performance of the proposed algorithm is explained by a numerical experiment. Results: MA showed better results than genetic algorithm(GA) and the convergence of the solutions in MA was also faster than GA. In addition, we could know from experiment that system reliability is increased and the chosen unit for redundancy allocation is changed if cost limit is increased. Conclusion: The chose unit for redundancy allocation is changed as resource constraints. It means we need to consider the alternative units in system design. In the future, we need to consider various problem related to redundancy allocation in multi level system and develop the better method to enhance search performance.