• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.12
• /
• pp.8187-8194
• /
• 2015

To accelerate a heavy roller coaster train with over 1G force, a lot of thrust is required and linear synchronous motor(LSM) as propulsion method is suitable for this kind of system. To increase the propulsion efficiency of LSM, precise and real-time position information of vehicle is required for accurate phase control. However, the discontinuous position information with relatively long time interval is usually transmitted from the hall-sensors on the track every magnet length. In this paper, the basic motor model based on traditional dq-axis equations is described and the motor dynamic model is produced by considering the cogging force and friction loss. To improve the position accuracy, the position estimator is also proposed for LSM control system. Simulations were performed to check the characteristics of the torque control system which includes the position estimator based on the motor model. Simulation results based on the linearized model show that this control system has an enough bandwidth and phase margin and the executed algorithm achieves an ideal effect to follow the real-time position signal. Therefore, the feasibility of position estimator is also confirmed.

• Journal of the Korea Concrete Institute
• /
• v.13 no.6
• /
• pp.544-552
• /
• 2001

Korea is classified into low and moderate seismic zone from the view-point of seismic hazard level. Korean seismic provisions has been developed based on UBC and ATC 3-06. Thus, in calculation of design base shear according to Korean provisions response modification factor (R) is included in the formula of design base shear. The major role of this factor is to reduce the elastic design base shear whereby structures can behave in inelastic range during design level earthquake ground motions(mean return period of 475 yrs.). R factor is assigned according to material and structural systems. In this study, R factor for bearing wall system is considered. Most of the walls of apartment buildings in Korea resist gravity and seismic loads simultaneously so that this wall system can be classified into bearing wall system. Structural details of these walls are different from those used in Japan and U.S.. They are all rectangular in sectional shape rather than barbell in shape, and also have special lateral reinforcement details at the boundaries of a wall. In Korean seismic design provisions(1988), two different values(3.0 and 3.5) of R factor are assigned to the bearing wall systems according to the wall details. However, in updated seismic provisions(2000), only one value is assigned to R factor(3.0) irrespective of wall details. In this study, the design base shear values in Korean seismic design provisions(1988, 2000), ATC 3-06, UBC are compared. Also experimental study was carried out to evaluate the seismic performance of structural walls. For this purpose, five test specimens were made which have special details used in apartment bearing wall systems in Korea. Based on the results of this study, response modification factor for bearing wall system is discussed.

• 한국HCI학회:학술대회논문집
• /
• 2008.02a
• /
• pp.648-653
• /
• 2008

With development of mobile communications terminal and expansion of mobile Internet, a large number of users can use mobile web contents at anytime and anywhere and will demand service of greater contents. Due to such demand, many studies are being carried out on transcoding contents so that wired web contents can be used in mobile web. However, transcoding and creation of mobile web contents involve difficulties because specifications available from telecommunications companies and mobile terminals have not been standardized. Especially, in order for serving dynamic object of wired web page contents to dynamically change according to time or user, it is required not only to program scripts to suit each terminal, but also to transcode the resources used in advance. For solution to this problem, this study uses the hierarchy structure of DOM (document object model) to display structural characteristics of wired web page. In other words, this study proposes the following technique Wired web pages are analyzed and the results are established as data structure. Then, dynamic object is extracted and the domain is indexed so that, when serving mobile web page, information can be extracted at the indexed position to create mobile web contents for service on real-time basis.

• Journal of the Korean earth science society
• /
• v.38 no.7
• /
• pp.496-510
• /
• 2017

This study presents a new nationwide quantitative precipitation estimation (QPE) based on the hybrid surface rainfall (HSR) technique using the weather radar network of Korea Meteorological Administration (KMA). This new nationwide HSR is characterized by the synthesis of reflectivity at the hybrid surface that is not affected by ground clutter, beam blockage, non-meteorological echoes, and bright band. The nationwide HSR is classified into static (STATIC) and dynamic HSR (DYNAMIC) mosaic depending on employing a quality control process, which is based on the fuzzy logic approach for single-polarization radar and the spatial texture technique for dual-polarization radar. The STATIC and DYNAMIC were evaluated by comparing with official and operational radar rainfall mosaic (MOSAIC) of KMA for 10 rainfall events from May to October 2014. The correlation coefficients within the block region of STATIC, DYNAMIC and MOSAIC are 0.52, 0.78, and 0.69, respectively, and their mean relative errors are 34.08, 30.08, and 40.71%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.6
• /
• pp.573-582
• /
• 2010

In this paper, X-band transceiver for high resolution wideband SAR systems is designed and fabricated. Also as a technique for enhancing the performance, error compensation algorithm is presented. The transceiver for SAR system is composed of transmitter, receiver, switch matrix and frequency generator. The receiver especially has 2 channel mono-pulse structure for ground moving target indication. The transceiver is able to provide the deramping signal for high resolution mode and select the receive bandwidth for receiving according to the operation mode. The transceiver had over 300 MHz bandwidth in X-band and 13.3 dBm output power which is appropriate to drive the T/R module. The receiver gain and noise figure was 39 dB and 3.96 dB respectively. The receive dynamic range was 30 dB and amplitude imbalance and phase imbalance of I/Q channel was ${\pm}$0.38 dBm and ${\pm}$3.47 degree respectively. The transceiver meets the required electrical performances through the individual tests. This paper shows the pulse error term depending on SAR performance was analyzed and range IRF was enhanced by applying the compensation technique.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.6
• /
• pp.771-777
• /
• 2017

This study investigated the rheological properties of Calrose rice flour dispersions as well as the effects of different thawing methods (steamer, smart oven, and microwave oven) on quality characteristics of frozen turmeric rice. Apparent viscosity, consistency index, and yield stress significantly increased at higher rice flour concentrations. Magnitudes of storage modulus and loss modulus significantly increased with elevation of rice flour concentration. Frozen turmeric rice thawed using a steamer had the highest moisture content and largest size (length, width, and thickness) among all thawing methods. The L values of turmeric rice after thawing using a steamer was significantly higher than those of other thawing methods. The a value of turmeric rice after thawing using a steamer was significantly lower than those of other thawing methods. Textural properties (hardness, adhesiveness, springiness, cohesiveness, brittleness, and chewiness) of frozen turmeric rice after thawing using a steamer were significantly lower than those of other thawing methods. Therefore, it can be concluded that frozen turmeric rice after thawing using a steamer might be desirable for improvement of texture.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.6D
• /
• pp.785-791
• /
• 2011

Two-lane and two-way traffic flow shows various dynamic relationships according to the behaviors of low-speed vehicle and overtaking. And it is essential to develop a vehicle model which simultaneously explains the behaviors of low-speed vehicle and overtaking using opposite lane in order to microscopically analyze various two-lane and two-way traffic flows by traffic flow simulation. In Korea, some studies for car-following and lane-changing models for freeway or signalized road have been reported, but few researches for the development of vehicle model for two-lane and two-way highway have been done. Hence, a microscopic two-lane and two-way vehicle model was, in this study, developed with the consideration of overtaking process and is based on CA (Cellular Automata) which is one of discrete time-space models. The developed model is parallel combined with an adjusted CA car-following model and an overtaking model. The results of experimental simulation showed that the car-following model explained the various macroscopic relationships of traffic flow and overtaking model reasonably generated the various behaviors of macroscopic traffic flows under the conditions of both opposite traffic flow and stochastic parameter to consider overtaking. The vehicle model presented in this study is expected to be used for the simulation of more various two-lane, two-way traffic flows.

• The Korean Journal of Nuclear Medicine
• /
• v.25 no.2
• /
• pp.219-226
• /
• 1991

골 신티 그라피는 섬유성 골 이형성증의 초기 병소와 다골성 형 섬유성 골 이형성증의 진단에 예민한 검사 방법이나, 양성 또는 악성 골 병변과의 감별진단에 어려움이 있었다. 이에 저자들은 조직학적으로 확진된 섬유성 골 이형성증 환자 17명에서 (단골성 형 12명, 다골성 형 : 5명) $^{99m}Tc-MDP$ (20 mCi 또는 7,400 MBq) 주사후 $2\sim4$시간에 전면, 후면 전신상과 부분상을 얻은 30부위 병소를 X선 사진과 비교분석 하였으며 CT, MRI 영상과 병리조직 소견을 얻었다. 병소 침습 부위별로는 대퇴골-10예, 경골-4, 요골-2, 늑골-2, 척추골-2, 후두골-2, 장골-2, 두정골-1, 하악골-1, 접형골-1, 견갑골-1, 쇄골-1, 척골-1예 였으며 5명의 다골성 형에서는 :우 대퇴골과 우 비골 : 양측 말단 대퇴골 :좌 경골과 좌 대퇴골 :우 요골과 우 장골 양측 대퇴골, 양측 경골, 접형골, 두정골, 척추골, 늑골과 장골이었다. 골 신티 그라피 소견상 30예중 28예에서(28/30, 93.3%) 방사능 섭취 증가를 보였으며 2예에서(2/30, 6.7%)는 정상 방사능 섭취 소견을 보였으나 각각은 X선상 불투명 유리상과 골흡수 병변을 보였다. 하악골의 골 3상 스캔상 병소에 현저한 혈류 증가가 관찰되었다. X선 소견상 30예중 11예에서 (l1/30, 36.7%) 불투명 유리상의 병변을, 골 변형을 동반한 1예를 포함한 18예에서는 (18/30, 60.0%) 골흡수 병변을 보였으며, 1예의 늑골 병변은 정상소견을 보였다(1/30, 3.3%). 이상에서 골 신티 그라피 만으로 섬유성 골 이형성증을 진단하는데는 주의를 요하나 골 대사의 동적 측면인 혈류와 골 재형성 양상 특히, 초기 병변과 단골성 형 침습에서 다골성 형을 진단하는데 필수적이며 결론적으로 골 신티 그라피와 X선 촬영등은 섬유성 골 이형성증 진단에 상호보완적인 검사 방법으로 사료된다.

• Applied Chemistry for Engineering
• /
• v.26 no.1
• /
• pp.53-58
• /
• 2015

Polycarbonate (PC)/graphene oxide (GO) composites with 3 phr of GO were prepared by using a twin screw extruder at 240, 260, and $280^{\circ}C$ after mixing the solution with chloroform. It was confirmed by DSC and TGA that the glass transition temperature ($T_g$) of PC/GO composites were not changed and the thermal stability was the best in case of the extrusion temperature at $260^{\circ}C$. Thermo mechanical properties of PC/GO composites according to extrusion temperatures were measured by dynamic mechanical analysis (DMA). Storage moduli of PC/GO composites were higher than that of pure PC and there was no detectable changes at varying the extrusion temperature. Based on these results, the extrusion temperature of PC/GO composites was fixed at $260^{\circ}C$. The degree of the chemical reaction of PC/GO composites with respect to the GO reduction time was confirmed by the C-H stretching peak at $3000cm^{-1}$ and the degree of the chemical reaction was similar to that of GO when the reduction time was 1 h. A decrease in the complex viscosity as a function of the GO reduction time was detected by dynamic rheometer, which may be originated from the enhancement of GO dispersion by PC-GO reaction. The GO dispersion was confirmed by scanning electron microscope (SEM).

• Applied Chemistry for Engineering
• /
• v.26 no.2
• /
• pp.173-177
• /
• 2015

In this study, effects of both the grafted ABS-g-MAH and the added graphene oxide (GO) on the impact strength of polycarbonate (PC)/poly(acrylonitrile-butadiene-styrene) (ABS) blends were discussed. The PC/ABS blends and PC/ABS/GO composites were fabricated by using twin screw extruder with ABS-g-MAH as a compatibilizer. The ABS-g-MAH was prepared by melting extrusion of ABS and maleic anhydride (MAH) with DCP (dicumyl peroxide) as an initiator using twin screw extruder and the synthesis of ABS-g-MAH was confirmed by the presence of carbonyl group (C=O) peak at $1780cm^{-1}$ of FT-IR spectrum. According to the thermal, rheological, and impact properties of PC/ABS blends, 5 phr (parts per hundred resin) of compatibilizer was chosen as an optimum content for the PC/ABS/GO composites. It was observed that the thermal decomposition of ABS/PC/GO composites increased with GO contents, but there was no significant changes or a decrease in the impact strength. Also the composite fabricated by ABS/GO showed small increase in the impact strength. From the result of the dynamic rheometer to observe the processing properties, the complex viscosities of PC/ABS blend including the compatibilizer increased, but the complex viscosities of composites added GO were not changed.