• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.403-408
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• 2016

Lithium-ion batteries are commonly employed in hybrid electric vehicles (HEVs), and achieving high energy density in the battery has been one of the most critical issues in the automotive industry. Because liquid cooling containing antifreeze is important in automotive batteries to enable cold starts, an effective geometric configuration for high-cooling performance should be carefully investigated. Battery cooling with antifreeze has also been considered to realize successful cold starts. In this article, we theoretically investigate a specific property of an antifreeze cooling battery system, and we perform numerical modeling to satisfy the required thermal specifications. Because a typical battery system in HEVs consists of multiple stacked battery cells, the cooling performance is determined mainly by the special properties of antifreeze in the coolant passage, which dissipates heat generated from the battery cells. We propose that the required cooling performance can be realized by performing numerical simulations of different geometric configurations for battery cooling. Furthermore, we perform a theoretical analysis as a design guideline to optimize the cooling performance with minimum power consumption by the cooling pump.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.221-226
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• 2015

Ru catalysts supported on $CeO_2$ were synthesized by an impregnation method and characterized by numerous analytical techniques including X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). Upon utilization of these catalysts for methane dry reforming with a $CH_4/CO_2$ ratio of 1:1 at different temperatures ranging from 550 to $750^{\circ}C$, the $Ru/CeO_2$ catalysts have shown to be active. In particular, Ru(0.55wt%) supported on $CeO_2$ (1) prepared by a hydrothermal method exhibited excellent activity with the conversion of > 75% at $750^{\circ}C$. In addition, the catalyst also proved to be highly stable for at least 47 h without catalyst deactivation under the dry reforming conditions.

• Convergence Security Journal
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• v.17 no.3
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• pp.83-93
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• 2017

The U.S.-China Relations could be analyzed two perspectives and their basis under major international p olitics theory-power transition with conditions: (1) North Korean's nuclear puzzle, (2) THAAD in the Kor ean Peninsula and (3) the U.S.-ROK Alliance. One perspective is the global order dominates the regional order, and then stable regional order comes out. The other is the regional order dominates the global ord er, and China wages a regional hegemonic conflict against the United States. Consequently, America's o verwhelming leadership in North Korean's nuclear, THAAD and U.S.-ROK Alliance as national power is expected to endure. But China also has expected empowerment and cooperation for the peace and stabilit y on the Korean Peninsula military problems. In this perspective, South Korea needs to pay attention to the changing power distribution and competition between the U.S. and China and needs to strengthen a balancing and harmonious diplomatic strategy, so called 'see-saw diplomacy'.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.5
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• pp.533-538
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• 2004

This paper proposes a systematic method to develop short-term electrical load forecasting systems using neuro-fuzzy models. The proposed system predicts the electrical loads with the lead times of 1 hour, 24 hour, and 168 hour. To do so, the load forecasting system first builds an initial structure off-line for each hour of four day types and then stores the resultant initial structures in the initial structure bank. 96 initial structures are constructed for each prediction lead time. Whenever a prediction needs to be made, the proposed system initializes the neuro-fuzzy model with the appropriate initial structure stored and trains the initialized prediction modell. To improve the performance of the prediction system in terms of accuracy and reliability at the same time, the prediction model employs only two inputs. It makes possible to interpret the fuzzy rules to be learned. In order to demonstrate the viability of the proposed method, we develop a load forecasting system by using the real load data collected during 1996 and 1997 at KEPCO. Simulation results reveal that the prediction system developed in this paper can achieve a remarkable improvement on both accuracy and reliability

• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.709-714
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• 2005

The purpose of this research is to verify the strategic fitness and relevance of the hub port strategy by SCM in Northeast Asia and to find a method to be a hub-port with a competitive edge. The fitness of the hub port development strategy is analysed by the structural equation model. The essential results of the research show that minimizing lead time from arrival of ship to inland transport and maximizing logistic services of each stage are important to provide optimal logistic service. And value-added port supply chain strategy is highly co-related with all the parts of port operation system, port transport system, distribution park and port information system. It shows that: various value added logistic service activity is more important than lowing cost; inland multimodal system should be rightly connected; distribution park should be connected to industry park to be a port cluster; and port information system should be developed.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.7
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• pp.335-343
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• 2006

We have designed the system that measure one channel ECG by two electrode and extract real-time EDR with more related resipiration and comportable to subject by using conductive textile. On the assumption that relation between RL electrode and potential measurement electrode is coupled with RC connected model, we designed RL drive output to feedback two electrode for reduction of common mode signal. The conductive textile which was used for two ECG electrode was offered more comfort during night sleep in bed than any other method using attachments. In the method of single-lead EDR, R wave point or QRS interval area could be used for EDR estimation in traditional method, it is, so to speak, the amplitude modulation(AM) method for EDR. Alternatively, R-R interval could be used for frequency modulation(FM) method based on Respiratory Sinus Arrhythmia(RSA). For evaluation of performance on AM EDR and FM EDR from 14 subject, ECG lead III was measured. Each EDR was compared with both temperature around nose(direct measurement of respiration) and respiration signal from thoracic belt(indirect measurement of respiration) on mean squared error(MSE), cross correlation(Xcorr), and Coherence. The upsampling interpolation technique of multirate signal processing is applied to interpolating data instead of cubic spline interpolation. As a result, we showed the real-time EDR extraction processing to be implemented at micro-controller.

• Journal of the Korea Computer Graphics Society
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• v.16 no.2
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• pp.9-17
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• 2010

Minkowski sum of two polyedra is an operation to compute the sum of all pairs of points contained in the polyhedra. It has been a very useful tool to solve many geometric problems arising in the areas of robotics, NC machining, solid modeling, and so on. However, very few algorithms have been proposed to compute Minkowski sum of polyhedra, because computing Minkowski sum boundaries is susceptible to roundoff errors. We propose an algorithm to robustly compute the Minkowski sum boundaries by employing the controlled linear perturbation scheme to prevent numerically ambiguous and degenerate cases from occurring. According to our experiments, our algorithm computes the Minkowski sum boundaries with the precision of $10^{-14}$ by perturbing the vertices of the input polyhedra up to $10^{-10}$.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.4
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• pp.1-4
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• 2009

This work shows how the adoption of a dual-dicing process for silicon wafer separation affects the thermal-cycling reliability (i.e. $-65^{\circ}C$ to $150^{\circ}C$) of the semiconductor devices utilizing lead-on-chip (LOC) die attach technique. In-situ examinations show that conventional single-dicing process directly attacks the edge region of diced devices but dual-dicing process effectively protects the edge region of diced devices from dicing-induced mechanical damage. Probably, this is because the preferential and sacrificial fracture of notched regions induced on the active surface of wafers saves the edge regions. It was also investigated through thermal-cycling tests that the number of thermal-cycling induced failures is much lower at the dual-dicing process than the single-dicing process.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.9 no.2
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• pp.115-127
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• 1998

Laryngopharyngeal reflux(LPR) is one firm of the gastroesophageal reflux diseases(GERD). It is known to cause various kinds of otolaryngologic symptoms such as hoarseness, foreign body sensation in throat, chronic throat clearing, chronic cough, etc. Disease entities diagnosed by otolaryngologists as posterior laryngitis, globus pharyngeus should be suspected as LPR-related diseases. In this multi-center trial, we tried to evaluate the effect of cisapride(10mg tid) on LPR-related symptoms as the part I study(CIS-KOR-051) in 19 centers, and as the part II study(CIS-KOR-052) comparative evaluation of effect between cisapride(10mg tid) and ranitidine(150mg bid) on LPR-related symptoms in 4 centers. In part I study, efficacy of cisapride on LPR-related symptoms after 4 weeks was 53.5% and that of after 8weeks was 77.9% in per protocol(PPA) analysis group. In part II study, efficacy of the cisapride was much better than that of ranitidine not only from 8 weeks trial(p<0.001) but also from 4 weeks trial(p<0.021) in PPA group. In the multiple logistic regression analysis among the parameters which affect the efficacy of the treatment, cisapride prescribed group showed 10 times greater than that of ranitidine prescribed group(p<0.0001, Odds ratio : 10) in PPA group. LPR was proved by 24Hr double probe pHmetry in 13 patients out of 19 patients tested(68.4%). Thus these results indicated that inducing the improvement of motility functions could affect the amelioration of the LPR-related symptoms much better than reducing acid secretion from the stomach. And maybe it suggests that LPR-related symptoms mainly developed by the reduced motility functions of the esophagus and/or delayed gastric emptying.

• Journal of the Korean Magnetics Society
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• v.12 no.2
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• pp.68-72
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• 2002

In this research, the effects of capacitance to the access time were studied at the junction area of tunneling magnetoresistance when these were used as memory devices. These results were obtained by applying electric signal input and magnetic field was not used. We applied bipolar square waves of 1MHz to the MTJ samples to obtain the results and time constant ($\tau$) calculated by observing wave responses utilizing an oscilloscope. And time constant was compared with junction area. Each part of MTJ sample, such as electrical pad, lead and contact area, was modeled as an electrical equivalent circuit based on experimental results. For the 200㎛$\times$200㎛ cell, junction capacitance was 90 pF. Also, measurement and simulation results were compared, which showed those similarity.