• 한국표면공학회지
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• 제26권6호
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• pp.299-306
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• 1993

The characteristic of synthesized potassium hexatitanate and manufacturing of thin film type matrix for battery was studied. After ball milled the mixture with 1:4 of $K_2CO_3$ and TiO2, mixsture was sintered at 85$0^{\circ}C$ and its product was confirmed with XRD. Adding the PTFE to the obtained potassium hexatitanate according to there various ball-mill time to control its particle size, thin film type matrix was manufactured. The high-est wettability of 50% was found with 12 hour ball milled powder containing 10w/o of PTFE and also it shown good mechanical properties. The matrix with $K_2O$$\cdot$$6TiO_2$ whisker shown 170% of wettability. Thed char-acteristics of matrix made by whisker and powder mixture were compared with the investigation of bubbled pressure and pore size distribution to improve its mechanical properties.

• Smart Structures and Systems
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• 제23권3호
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• pp.307-318
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• 2019

The frequently excessive vibrations presented in civil structures during seismic events or service conditions may result in users' discomfort, or worst, in structures failure, producing economic and even human casualties. This work contributes in proposing the synthesis of a nonlinear optimal control strategy for semiactive structural control, with the main characteristic that the synthesis considers both the structure model and the semiactive actuator nonlinear dynamics, which produces a nonlinear system that requires a nonlinear controller design. The aim is to reduce the unwanted vibrations in the response of civil structures, by means of intelligent fluid semiactive actuator such as the Magnetorheological Damper (MRD), which is a device with a low level of power consumption. The civil structures for which the proposed control methodology can be applied are those admitting a state-dependent coefficient factorized representation model, such as buildings, bridges, among others. A scaled model of a three storey building is analyzed as a case study, whose dynamical response involves displacement, velocity and acceleration of each one of the storeys, subjected to the North-South component of the September 19th., 2017, Puebla-Morelos (7.1M), Mexico earthquake. The investigation rests on comparing the structural response over time for two different conditions: with no control device installed and with one MRD installed between the first floor and the ground, where a nonlinear optimal signal for the MRD input voltage is determined. Simulation results are presented to show the effectiveness of the proposed controller for reducing the building's dynamical response.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.904-908
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• 2008

As the various industrial production machinery has come into being by development of industrial technology, the productivity of the basic industrial production machinery has improved and the international competitiveness of the one of Korea has strengthened. However, at the same time, noise from various industrial production machinery disturbs the quiet environment. There are 35 kinds of the noise emission machinery defined in the noise and vibration control act according to the horse power and the number of machinery. These were classified in 1992 through investigation from 1990 to 1991, and the characteristic of the noise emission machinery may be different from the past one. So we need to investigate the characteristics of the noise emitted by machinery to control it rightly. Also we need to investigate the new noise emission machinery which has come into being recently. In this survey, we measured sound intensity of 32 noise emission machinery to calculate the sound power levels of those and investigated the characteristic of the sound power level of those according to the frequency. From the survey, we found that the forging machine, concrete pipe and pile making machine, sawing machine, etc. are the noisy machinery. And the automatic packing machine, sewing machine, centrifuge, etc. are the silent machinery. Also the generator, the concrete pipe and pile making machine, the printing machine, etc. emit the low frequency noise, and the molding machine, the stone cutter, the metal cutter, etc. emit the high frequency noise. Lastly, we intented to propose the proper guide line of classifying noise emission machinery.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2211-2220
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• 2015

This paper analyzes multiple active management (AM) techniques of active distribution network (ADN), and proposes an optimal coordination model of intermittent distributed generation (IDG) accommodation considering the timing characteristic of load and IDG. The objective of the model is to maximize the daily amount of IDG accommodation under the uncertainties of IDG and load. Various active management techniques such as IDG curtailment, on-load tap changer (OLTC) tap adjusting, voltage regulator (VR) tap adjusting, shunt capacitors compensation and so on are fully considered. Genetic algorithm and Primal-Dual Interior Point Method (PDIPM) is used for the model solving. Point estimate method is used to simulate the uncertainties. Different scenarios are selected for the IDG accommodation capability investigation under different active management schemes. Finally a modified IEEE 123 case is used to testify the proposed accommodation model, the results show that the active management can largely increase the IDG accommodation and penetration.

• 대한한의학회지
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• 제24권2호
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• pp.19-31
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• 2003

Objectives : This study examined effects of kyeong points (經穴)' acupuncture of three hand yang collaterals (手三陽經) on the facial thermography in health subjects, because the kyeong point in Yang collaterals belongs to the characteristic of the five elements (五行)meaning fire (火). Methods : The volunteers who participating in this study rested for 20-30 min. atroom temperature (23-$25^{\circ}C$) before the examination and were informed to avoid smoking, drinking and use of any drugsfor the previous day. The thermography of the face was taken using Infra-Red Imaging System (IR 2000, MEDI-CORE Co., Korea) at time intervals of 15 minutes : at 15 min before, just before and after, 15 min after, 30 min after and 45 min after acupuncture stimulation. Acupuncture was applied to the left kyeong points (經穴)' of three hand yang collaterals (手三陽經) for 30 minutes. Results : The results showed that kyeong points (經穴)' acupuncture of three hand yang collaterals (手三陽經) decreased the temperature of all the areas of the facial surface comparing to those of the control group. Also, it was observed that the quantities of thermal changes following acupuncture of ST36 increased in the all ROIs (regions of interest) compared to those of the control group. Conclusions : Observing the thermography classified by ROI, it was clear that acupuncture of kyeong points (經穴) of three hand yang collaterals (手三陽經) could modulate thermogram of the facial area however, it is necessary to undertake more investigation supporting these results.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제13권3호
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• pp.231-240
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• 1991

The parents of twenty-five patients with cleft lip(with or without cleft palate), CL(P) and the parents of fifteen non-cleft patients were studied. Area measurements of cranium of brain case from lateral and frontal roentgenograms. The most important finding of this investigation was that the CL/CP parents had a significantly smaller brain case than did the control subjects. A smaller brain case may well be one morphological characteristic predisposing toward the cleft anomaly. The results obtained were as follows, 1) Total area measurements for brain case of parents of CWCP patients were significantly smaller than those in the control group, on the frontal view. 2) A significantly smaller parietal and occipital region on the frontal view vas noted in the parents of CL/CP patients. 3) A significantly smaller parietal region on the lateral view was noted in the mothers of CL/CP patients. 4) A significantly smaller mastoid area on the lateral view was noted in the parents of CL/CP patients.

• 한국항해학회지
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• 제4권1호
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• pp.31-50
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• 1980

It does not seem necessarily practicable to keep the system always in optimal condition, athough the control system of the follow-up mechanism on the most marine gyro compasses is to be adjusted by the operator through the gain adjustment. Sometimes a sustained oscillation or an incorrect gyro reading occurs to the system. For such a system any systematical research or theoretical basis of the guide for the optimal gain adjustment has not been reported yet. As a basic investigation of the theoretical system analysis to solve the problems concerned, the author attempts in this paper to express the system in a mathematical model deduced from the results of the theoretical approach and the experimental observation of each element contained in the follow-up mechanism of Hokshin D-1 gyro compass, and to constitute an over-all closed loop transfer function. This funciton being reverted to a fourth orderlinear differential equation, the first order simultaneous differential equations are obtained by means of the state-variables. The latter equations are solved by the Runge-Kutta method with digital computer. By comparing the characteristic of the simulated over-all output with that of the experimental result, it is shown that both outputs are nearly consistent with each other. It is also expected that the system representation proposed by this paper is valid and will be a prospective means in a further study on the design and optimal adjustment of the system.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1955-1963
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• 2021

As the IAEA has applied integrated safeguards and a state level approach to member states, the importance of national inspection has increased. However, the requirements for national inspection for some member states are different from the IAEA safeguards. In particular, the national inspection for the ROK requires on-site U concentration analysis due to a domestic notification. This research proposes an on-site U concentration analysis (OUCA) method for UO₂ pellets using gamma spectroscopy to satisfy the domestic notification requirement. The OUCA method calculates the U concentration of UO₂ pellets using the measured net X-ray counts and declared ²³⁵U enrichment. This research demonstrates the feasibility of the OUCA method using both MCNP simulation and experiment. It simulated and measured the net X-ray counts of different UO₂ pellets with different U concentrations and ²³⁵U enrichments. The simulated and measured net X-ray counts were fitted to polynomials as a function of U concentration and ²³⁵U enrichment. The goodness-of-fit results of both simulation and experiment demonstrated the feasibility of the OUCA method.

• Geomechanics and Engineering
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• 제14권5호
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• pp.421-428
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• 2018

In deep mining, the lateral deformation of strip coal pillar appears to be a new characteristic. In order to study the lateral deformation of coal-mass, a monitoring method and monitoring instrument were designed to investigate the lateral deformation of strip coal pillar in Tangkou Coalmine with the mining depth of over 1000 m. Because of without influence of repeated mining, the bedding sandstone roof is easy to break and the angle between maximum horizontal stress and the roadway is small, the maximum lateral deformation is only about 287 mm lower than the other pillars in the same coalmine. In deep mining, the energy accumulation and release cause a discontinuous damage in the heterogeneous coal-mass, and the lateral deformation of coal pillar shows discontinuity, step and mutation characters. These coal-masses not only show a higher plasticity but also the high brittleness at the same time, and its burst tendency is more obvious. According to the monitoring results and theoretical calculations, the yield zone of the coal pillar width is determined as 15.6 m. The monitoring results presented through this study are of great significance to the stability analysis and design of coal pillar.

• KIEAE Journal
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• 제16권6호
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• pp.39-50
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• 2016

Purpose: The purpose of this study is to be performed with studio-type housings among urban life-type housings to investigate the physical characteristic and crime-related factors of studios from the viewpoint of the basic principles of crime prevention through environmental design (CPTED). Method: Eight CPTED guidelines available in Korea were reviewed to select 20 planing factors for actual condition investigation. Five single households in studio-type housings in Gwanak-gu, Seoul, were chosen according to the subject screening criteria to perform the actual condition investigation. Results: First, a lighting plan around a building for natural surveillance should consider the building location, relation with the front road, and surrounding facilities. In a building of a piloti structure, the parking lot and the building gate should be arranged in a manner that enables natural surveillance. Second, the shape of the corridors in studio-type housings should be considered to plan the installation of a lighting at the door of each household, the installation of a viewer window at the door of each household, and the arrangement of the elevator. Third, to support access control, an access control system having the function of video and voice communication is recommended to be installed at the building gate. Criteria for the type of security windows and the floors on which security windows should be installed, and the regulations about the CCTV installation inside and outside the building should be prepared. Fourth, to enhance territoriality in parking lots, ground patterns, parking lot gate, and signs may be installed. Fifth, in view of effective utilization and maintenance, lighting facilities should be installed to increase the usability of ground parking lots, and relevant installation criteria should be prepared regarding the type, number, and brightness of the lightings.