• Journal of the military operations research society of Korea
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• v.1 no.1
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• pp.111-129
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• 1975

U.S. Air Force Regulation 80-1 defines that a weapon system is composed of equipments, skills, and techniques, the composite of which ferns an instrument of combat. The complete weapon system includes all related facilities, equipments, materials, services, and personnels required for the operation of the system, so that the instrument of combat can be considered as a self-sufficient unit of striking power in its intended operational environment. Effectiveness of a weapon system can be expressed as a function of its liability, reliability and performance capability. Among these attributes which influence the weapon effectiveness, performance capability is considered to be the most critical factor for many weapon systems. In order to illustrate the application of the methodology of performance capability, a specific ease study on the effectiveness of Vulcan anti-air craft gun system is presented with special emphasis on hitting probability on moving targets, effects of artificial rounds dispersion, and several principles related to the deployment of the system. This thesis includes the thorough survey of the possibility of calculating the absolute value of hitting probability on moving targets, indicates that the effects of artificial rounds dispersion increase the value of probability only when the total number of rounds fired within fire range exceeds a certain critical number, and suggests that concentrated guns deployment is better than scattered deployment in order to obtain higher probability and lower average amount of rounds if it is assumed that the effects of counter-attack from enemy threats are not serious.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.128-135
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• 2006

This paper presents a finite element method to analyze the free vibration of a flexible HDD composed of the spinning disk-spindle system with fluid dynamic bearings(FDBs), the head-suspension-actuator with pivot bearings, and the base plate with complicated geometry. Experimental modal testing shows that the proposed method well predicts tue vibration characteristics of a HDD. This research also shows that even the vibration motion of the spinning disk corresponding to half-speed whirl and the pure disk mode are transferred to a head-suspension-actuator and base plate through the air bearing and the pivot bearing consecutively. The proposed method can be effectively extended to investigate the forced vibration of a HDD and to design a robust HDD against shock.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.22-28
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• 2003

In the conventional weapon system, such as gun and small arms, it Is a general trend that for maximization of its performance and enhancement of its effectiveness, the firing control system(FCS) is developed and applied with the guns and small arms in the world. The FCS of the small arms for infantry man is composed of a few of sensors for acquisition of input data of FCS, such as range measurement, position sensing of weapon, temperature, etc., computer, displayer and power pack, and also the air burst munition is developed in parallel for the maximization of FCS's effectiveness. Since the flight time setting fuze for the air burst munition is adapted for next me, the measuring device of the muzzle velocity is needed to overcome the variation of muzzle velocity due to producing procedures and the differences of the using temperatures and so maintain the burst position accuracy This paper contained the technical information on the development of the measuring device of muzzle velocity, which designed in compact & light weight configuration with reliability and accuracy.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.2
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• pp.47-56
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• 2015

At the present, the mechanized form roads pavement was constructed with plain concrete. Mostly, it was used by welded wire mesh for preventing crack. Cellulose fibers for the reinforcement of concrete offer relatively high levels of elastic modulus, fiber count (per unit weight), specific surface, and bond strength to cement-based materials. The construction of concrete pavement confirmed that cellulose fiber reinforced concrete was applicable to mechanized form roads pavement. In the study, cellulose fibers were used here at 0.08 % volume fraction, which is equivalent to a fiber content of $1.2kg/m^3$. Cellulose fiber reinforced concrete were compared with plain concrete. Field test results indicated that cellulose fiber reinforced concrete showed slightly to increase of 28 days compressive strength and improved the initial strength. it tended to increase of splitting tensile strength. Test results showed that the slump and air content tend to decreased. but, the variation of air contends is very little. Also, construction cost of cellulose fiber reinforced concrete is less than about 25.7 % the case of welded wire mesh previously used. Therefore, The cost reduction is expected to be possible in construction site by mechanized form roads pavement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1127-1130
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• 2003

In the last several centuries, humankind have been experienced the material abundance with a development of technical civilization and being industrialized quickly. During the process of this, environmental pollutant have occurred naturally so that humankind have more interests for environment pollutant. Air pollution caused by exhaust from a car is very harmful for human. Most of exhaust from a gasoline engine are $CO_x(CO+CO_2),\;NO_x(NO+NO_2)$, and THC(Total Hydrocarbon). The method to remove these kinds of noxious gases are so many thing such as the three catalysts, $NO_x$ catalysts, Filter and so on. However, although air pollution caused by exhaust from motorcycle have also occurred very much, there is no regulation for motorcycle. In this paper, we studied to remove $CO_x(CO+CO_2),\;NO_x(NO+NO_2)$, THC exhaust from a motorcycle using non-thermal plasma In the result, $NO_x(NO+NO_2)$ concentration was decreased approximately 70% and THC(Total Hydrocarbon) was removed about 40%.

• Journal of Environmental Health Sciences
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• v.14 no.2
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• pp.29-41
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• 1988

This study was performed to investigate the air pollution levels in Daegu area titrough measuring of contents of water, chlorophyll, water soluble sulfur and lead metal in the leaves of roadside trees and chemical properties of soil under the urban trees. The results can be summarized as follows 1. The range of water content was from 60.4% to 74.6%. The comparisons of chlorophyll, water soluble sulfur and water content were regression equation, chlorophyll=0.1981+ 0.0040 water content (July), water soluble sulfur=3,139-0.0416 water content (July). and correlation coefficient, r=0.561 and r=0.549 respectively 2. Average contents of chlorophyll, water soluble sulfur and lead metal in the leaves of roadside tree at sampling sites were chlorophyll 0.050, 0.072mg/cm$^2$, water soluble sulfur 0.244, 0.333%, and lead metal 12.25, 12.68ppm in Oct. and Jul. respectively. 3. Correlation between chlorophyll and contents of water soluble sulfur and lead metal in the leaves of roadside tree at sampling sites were water soluble sulfur r=-0.564, -0.613 and lead metal r=-0.693, -0.699 in October and July, respectively. 4. Correlation between chlorophyll and water content, water soluble sulfur and lead metal in the leaves of tree showed positive significance.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.97-102
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• 2003

Experimental investigations were carried out in an atmospheric pressure, optically accessible and laboratory-scale dump combustor operating on natural gas. The objective of this study is to obtain the phase-resolved gas temperatures at different phases of the oscillating pressure cycle during unstable combustion. CARS temperature measurements were made at several spatial locations under lean premixed conditions to get the information on temperature field within the combustor. Also the effect of incomplete fuel-air mixing on phase-resolved temperature fluctuation was investigated. Results including phase-resolved averaged temperature, normalized standard deviation and temperature probability distribution functions (PDFs) were provided in this paper. Temperature PDFs give an insight on the flame behavior. And strong correlation between phase-resolved temperature profile and pressure cycle was observed. Results of the phase-resolved high temperature give an additional information on the perturbation of equivalence ratio at flame as well as the effect of mixing quality on NOx emission characteristics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.1 s.118
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• pp.24-32
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• 2007

This paper presents a finite element method to analyze the free vibration of a flexible HDD composed of the spinning disk-spindle system with fluid dynamic bearings(FDBs), the head-suspension-actuator with pivot bearings, and the base plate with complicated geometry. Experimental modal testing shows that the proposed method well predicts the vibration characteristics of a HDD. This research also shows that even the vibration motion of the spinning disk corresponding to half-speed whirl and the pure disk mode are transferred to a head-suspension-actuator and base plate through the air bearing and the pivot bearing consecutively. The proposed method can be effectively extended to investigate the forced vibration of a HDD and to design a robust HDD against shock.

• Atmosphere
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• v.16 no.1
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• pp.1-17
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• 2006

The purpose of this study is to find out the change of statistical characteristics of typhoons affecting the Korean Peninsula. For this purpose, we analyzed the occurrence frequency of typhoon for 50 years (1954-2003) and change of air temperature and sea surface temperature near the Korean Peninsula in the same period. We classified typhoon tracks affecting the Korean Peninsula, and analyzed their trends and the amount of damage by typhoon. While the annual occurrence frequency of typhoon in the western North Pacific gradually decreased, its frequency affecting the Korean Peninsula increased. In addition, the occurrence location migrated northward. This coincides with the increase in air temperature and sea surface temperature around the Korean Peninsula. Typhoon tracks affecting the Korean Peninsula were classified into 7 types. Among them, the occurrence frequency of type 6 and 7 has increased. Although the occurrence frequency is low in type 2, the amount of damage by typhoon and occurrence frequency are increasing recently.

• Journal of the Korean Ceramic Society
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• v.50 no.5
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• pp.326-332
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• 2013

In this study, we prepared yttria stabilized zirconia granules for thermal barrier coatings using a spray drying process. First, we characterized the properties of granules such as flow rate and packing density for utilizing the air plasma spray process. The flow rate and packing density data showed 0.732 g/sec and 2.14 $g/cm^3$, respectively, when we used larger and denser particles, which are better than hollow granules or smaller spherical granules. Second, we chose larger, spherical granules fabricated in alcohol solvent as starting powders and sprayed it on the bondcoat/nimonic alloy by an atmospheric plasma spray process varying the process parameters, the feeding rate, gun speed and spray distance. Finally, we evaluated representative thermal and mechanical characteristics. The thermal expansion coefficients of the coatings were $11{\sim}12.7{\times}10^{-6}/^{\circ}C$ and the indentation stress measured was 2.5 GPa at 0.15 of indentation strain.