• Journal of Surface Science and Engineering
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• v.23 no.1
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• pp.44-51
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• 1990

Effects of temperature on the tensile properties of annealed and hydirded Zircaloy-4 plate in which hydrides are precitated paralled to the rolling direction were investigated. The main results obtained are as follows : 1) In annealed Zircaloy-4, yield point phenomenon was found in the temperature range of $200-550^{\circ}C$, while in hydrided alloy the phenomenon was found in the range of $200-400^{\circ}C$. 2) The dynamic strain aging behavior was occurd in the temperature interval of 400-$550^{\circ}C$in both annealed and hydrided Zircaloy-4. 3) The nearly values of yield strength, tensile stength and elongation are obtained in both annealed and hydried Zircaloy-4. From this result, we are led to conclude that the hydrides which are preiptated parallel to the circumferenial direction of nucler fuel are not so harmful for tensile properties of the clad.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.3-5
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• 2007

Many continuous queries are important to be process efficiently in a data stream environment. It is applied a query index technique that takes linear performance irrespective of the number and width of intervals for processing many continuous queries. Previous researches are not able to support the dynamic insertion and deletion to arrange intervals for constructing an index previously. It shows that the insertion and search performance is slowed by the number and width of interval inserted. Many intervals have to be inserted and searched linearly in a data stream environment. Therefore, we propose Hashed Multiple Lists in order to process continuous queries linearly. Proposed technique shows fast linear search performance. It can be utilized the systems applying a sensor network, and preprocessing technique of spatiotemporal data mining.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.579-585
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• 2008

Numerous experimental investigations on metallic materials and solid polymers have shown that relaxation behavior is nonlinearly dependent on prior strain rate. The stress drops in a constant time interval nonlinearly increase with an increase of prior strain rate. And the relaxed stress associated with the fastest prior strain rate has the smallest stress magnitude at the end of relaxation periods. This paper deals with the performance of three classes of unified constitutive models in predicting the characteristic behaviors of relaxation. The three classes of models are categorized by a rate sensitivity of kinematic hardening rule. The first class uses rate-independent kinematic hardening rule that includes the competing effect of strain hardening and dynamic recovery. In the second class, a stress rate term is incorporated into the rate-independent kinematic hardening rule. The final one uses a rate-dependent format of kinematic hardening rule.

• 한국해양학회지
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• v.8 no.1
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• pp.4-8
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• 1973

Recent dynamic computations of zonal flow and analysis of oceanographic data of CSK in winter indicate year-to year variations in the location and dynmic structure of the Subtropic Countercurrent in the western North Pacific. In January 1966, the Subtropical Countercurrent migrated southward to 21$^{\circ}$- 22$^{\circ}$N Lat in association with the subsurface Subtropical Convergence. At the area of 25$^{\circ}$- 26$^{\circ}$N Lat, another surface thermal front was formed along which a stronger eastward flow of approximately 0.4kt is seen. On the section of 142$^{\circ}$E Long in January 1967, eastward flow appears at every interval of 2$^{\circ}$latitude in the northern waters of 20$^{\circ}$N Lat.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.12a
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• pp.81-88
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• 2004

GIS (geographic information system) applications increasingly require the representation of geospatial objects with fuzzy extent and querying of time-varying information. In this paper, we Introduce a FSTDB (fuzzy spatiotemporal database) to represent and manage states and events causing changes of dynamic fuzzy objects using fuzzy set theory. We also propose the algorithms for the operators to be included in a GIS to make it able to answer queries depending on fuzzy predicates during a time interval and a method to identify the development process of objects during a certain period based on the designed database. They can be used in application areas handling time-varying geospatial data, including global change (as in climate or land cover change) and social (demographic, health, ect.) application.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.58-65
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• 1998

A purpose of this research is to develope the calculation methods of design input seismic loads, Where, calculation methods are ; (1) Considering different recurrence period of earthquakes which was proposed by ATC 14. (2) Using earthquake records which was modified Korean codes. Responce spectra that was adopted by codes has an estimated recurrence interval of 500 years, with approximately a 90 percent probability of not being exceeded in 50 years. But If we considered the life-time of existing buildings in some cases, response spectra be modified with return period of earthquakes. If we be design highrise and irregular buildings, dynamic analysis method that use time history records should be used. But in Korea, time history records of earthquakes was very few. Therefore to use foreign countries's earthquake record, it is need to select of records considered Korean coeds. As a results, this study propose a calculation method of seismic design input loads that considered return period of earthquakes and also propose using method of earthquakes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.1
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• pp.22-29
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• 2003

The study was to evaluate psychological and physiological changes of simulator sickness in the controlled condition of driving a car (1 hr. at speed of 60 km/h) in a graphic simulator. Simulator sickness was measured and analyzed every 5 min using both subjective responses(i.e., Simulator Sickness Questionnaire) and Physiological signals(EEG, HRV, Skin Temperature, GSR). The results showed that there was significant differences in subjective response 10 min after the main experiment. From 10 min after the driving, the level of subjective simulator sickness increased significantly, relative one of the rest condition. There also was significant differences in physiological responses between the rest and the 5 min after from the start of driving : for EEG, $\delta$ and $\theta$ at Fz area increased, while $\alpha$ decreased; the averaged R-R interval and skin temperature decreased; LF/HF and GSR increased. The results indicated that simulator sickness was induced by activation of the autonomic nerves and inactivation of the central nerves.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.265-269
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• 2009

The through-thickness variations of strain and microstructure during high-speed hot rolled 5052 aluminum alloy sheet were investigated. The specimens were rolled at temperature ranges from 410 to $560^{\circ}C$ at a rolling speed of 15 m/s without lubrication and quenched into water at an interval of 30 ms after rolling. The redundant shear strain induced by high friction between rolls and the aluminum sheet was increased largely beneath the surface at a rolling reduction above 50%. Dynamic recrystallization occurred in the surface regions of the specimen rolled under conditions of high temperatures or high rolling reductions.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.327-331
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• 2008

The problems of power factor and harmonics are occurred in converter system which used to SCRs and diodes as power semiconductor devices IGBT was solved that problem, maintain the input line current with sinusoidal wave current of input power source voltage. In this paper, three phase AC to DC boost converter that operates with unity power factor and sinusoidal input currents is presented. The current control of the converter is based on the space vector PWM strategy with fixed switching frequency and the input current tracks the reference current within one sampling time interval. Space vector PWM strategy for current control was materialized as a digital control method. By using this control strategy low ripples in the output voltage, low harmonics in the input current and fast dynamic responses are achieved with a small capacitance in the dc link.

• Annual Conference of KIPS
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• 2000.10b
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• pp.1565-1568
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• 2000

본 논문에서는 기존 폭주 회피형 ERICA+ 알고리즘에서 ER 피드백 계산에 이용되는 부하지수, 가용용량, 활성 가상회선 수 등에 영향을 미치는 측정간격을 기존의 Cell 단위나 Time 단위가 아닌, 목적 큐 길이를 기준으로 현재 스위치의 큐 길이의 변화에 따라 파라미터를 측정함으로써, 큐 지연은 물론이고 ACR과 Fair Share의 진동을 줄일 수 있고, 일시적인 트래픽 폭주에 동적으로 반응할 수 없거나 빈번한 측정으로 인한 시스템의 복잡도와 고속화 문제를 해결한 안정적인 알고리즘을 제안하고 시뮬레이션 수행을 통하여 기존의 방법과 비교 분석한다.