• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.325-328
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• 2001

In this work, Cell search which is one of the important abilities of W-CDMA system in Reyleigh s fading channel is studied by using Cell Searcher of asynchronous IMT-2000 system(3GPP) and Cell - search simulation. For the methods of cell search to optimize codes, three stages are considered: 1) slot synchronization, 2) frame synchronization, and 3) scrambling code identification. It is found that key system parameters such as Primary Synchronization Channel (P-SCH), Secondary L Synchronization Channel(S-SCH), and Common Pilot Channel (CPCH) loading factor are optimized. It is noted that the smaller Optimal threshold value, the larger SNR of the received singnal. Therefore, It is important that the optimal threshold value is selected in the region of SNR

• KEPCO Journal on Electric Power and Energy
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• 제3권2호
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• pp.127-131
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• 2017

The present paper describes the slagging field data obtained with the one-dimensional process model for the 500 MW tangentially coal fired boiler in Korea. To obtain slagging field data in terms of thermal resistances [$m^2{\cdot}^{\circ}C/kW$], a number of plant data were collected and analyzed with the one-dimensional modelling software at 500 MW full load. The slagging field data for the primary superheater were obtained for six coal blends, and compared with two TMA (Thermo-Mechanical analyzer) slagging indices and the numerical slagging index, along with the conventional slagging indices which were modified with the ash loading. The advanced two TMA indices for six blended coals give a good slagging tendency when comparing them with the slagging field data, while the modified conventional slagging indices give a relatively poor agreement.

• 대한기계학회논문집A
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• 제32권12호
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• pp.1123-1131
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• 2008

This paper provides V-factor estimation under combined mechanical and thermal load for circumferential cracks. Results are based on finite element analyses and effect of types and magnitudes of the thermal stress, crack geometry, the loading mode and plastic strain hardening on variations of the V-factor are investigated. The results of finite element analyses are compared with R6 values. As a result, it is shown that R6 gives generally conservative results. The conservatism is especially increased for the combination of large mechanical and thermal load. As a result, new estimation method which uses failure assessment line in R6 is proposed for V-factor and gives less conservative results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.776-781
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• 2001

Internal pipes technology for LNG Storage tank developed because of the perceived safety risk of having an opening near the base of the shell. This is because the shell at this point is the most highly stressed component of the primary containment. other, secondary, problems arise because the movement of the tank in this region is also at a maximum. This requires the use of bellows either in the interspace or on the outside of the outer tank. Therefore the internal pipe, through the roof, solves these problems. The loading conditions calculated from design concept are then used to perform a pipe stress analysis. As well as determining the stresses in the internal pipe and checking against allowable stress, it determines the reaction forces at the support positions.

• 대한전기학회논문지:전력기술부문A
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• 제53권3호
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• pp.161-167
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• 2004

Zone 3 of the distance relay is used to provide the remote back-up protection in case of the failure of the primary protection. However, the risk lot mal-operations under stressed conditions such as heavy loading, voltage and transient instability is usually high. Zone 3 is used in combination with the derivatives of the voltage, and current, etc to prevent mal-operations. Sometimes, the impedance characteristics that restrict the tripping area of relay are used to avoid the mal-operations due to load encroachment. This paper presents a novel Zone 3 scheme based on combining the steady-state components (i.e. 60Hz) and the transient components (TCs) using a state diagram that visualizes the sequence of studies that emanate from the sequence of events. The simulation results show that the novel zone 3 distance relay elements using the proposed method operates correctly for the various events.

• 한국정밀공학회지
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• 제20권2호
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• pp.129-135
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• 2003

The fatigue life of a structure can be enhanced by improving the mechanical and metallurgical aspects to strengthen the material around regions of high stress. Coldworking of holes in structures is one of the mechanical methods of strengthening material. The material for this research is A12024-T351 which is used for the primary member or aircraft. Specimens were tested under constant amplitude loading and residual stresses measured by X-ray diffraction technique. Fatigue crack initiation life was evaluated by a strain-life equation which was considered initial residual stress and residual stress relaxation exponent as a function of the strain amplitude. The predictions on fatigue crack initiation life were compared with experimental results. A wide range of discrepancies between them was found.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 춘계학술대회 논문요약집
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• pp.188-188
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• 2004

Modal testing and analysis is a primary tool for obtaining reliable models to represent the dynamics of structures. When a structure is tested in order to collect measured data in modal testing, we usually use attached accelerometers to pick up the response data. Change in modal parameters due to the mass of transducers in modal testing is a well-known problem. The disadvantages are the shift of measured modal frequencies and the change of modal shapes, which can cause inaccurate results in further analysis. Modal analysis methods in frequency domain are based on a set of measured frequency response functions(FRF).(omitted)

• 대한기계학회논문집
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• 제18권11호
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• pp.2805-2816
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• 1994

This paper describes dynamic finite element analyses performed to study the dynamic behaviors of a shipping container under the impact onto rigid target due to the accidental fall from the hight of 9 m. Using two and three dimensional techniques, the shipping container which gave the maximum damage, ten different drop orientations are considered ; at intervals of $5^{\circ}$ from $45^{\circ}$ to $90^{\circ}$ According to the present results, the orientation of the shipping container which gave the maximum damage is $85^{\circ}$ from horizontal for oblique drop in the primary impact. In the optimal design of the shipping container, the impact limiter material must be considered importantly because it's proper selection affects the weight and the manufacturing cost of the shipping container. The analysis of the shipping container in this paper demonstrated that the shipping container is structurally sound relative to the regulatory drop test requirements.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.789-794
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• 1999

The performance of a small on-site wastewater treatment system consisting of an anaerobic septic tank and upgraded absorbent biofilter was investgted . The anaerobic septic tank was used as a pre-treatment of the absorbent Biofitler instead of the primary clarifier. The treatment capacity of the system was examined by changing the hydraulinc loadings to the Absorbent Biofilter as 2.5㎥/day , 4.5㎥/day, 6.0㎥/day, respective. The effluent from the septic tank was fed into the Absorbent Bilfilter. Based on the experimental results, the quality of treated wastewater satisfied the regulation and the BOD and SS was removed down to approximately 5mg/$\ell$ and 1mg/$\ell$, respectively.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 봄 학술발표회 논문집
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• pp.9-18
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• 1996

The primary objective of this paper is to grasp many characteristics of buckling behavior of latticed spherical domes under various conditions. The Arc-Length Method proposed by E.Riks is used for the computation and evaluation of geometrically nonlinear fundamental equilibrium paths and bifurcation points. And the direction of the path after the bifurcation point is decided by means of Hosono's concept. Three different nonlinear stiffness matrices of the Slope-Deflection Method are derived for the system with rigid nodes and results of the numerical analysis are examined in regard in geometrical parameters such as slenderness ratio, half-open angle, boundary conditions, and various loading types. But in case of analytical model 2 (rigid node), the post-buckling path could not be surveyed because of Newton-Raphson iteration process being diversed on the critical point since many eigenvalues become zero simultaneously.