• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.629-637
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• 2017

Severe dust explosions occurred frequently in food processing industries and explosion damage increase by flame propagation in pipes or plants. However there are few fire explosion data available due to various powder characteristics. We investigated the characteristics of ignition and explosion on sugar, cornstarch and flour dust with high frequency accidents and high social demand. The measurements showed the median diameter of 27.56, 14.76, $138.5{\mu}m$ and ignition temperature has been investigated using by thermo-gravimetric analysis (TGA) and differential scanning calorimeter (DSC). The maximum explosion pressure ($P_m$) and dust explosion index ($K_{st}$) of sugar, cornstarch and flour are 7.6, 7.6, 6.1 bar and 153, 133, 61 [$m{\cdot}bar/s$], respectively. The flame propagation time in duct was calculated in order to evaluate the damage increase due to flame propagation during dust explosion. The explosion hazard increase due to flame propagation was higher in the order of sugar, flour and cornstarch dust.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1389-1397
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• 2016

This study was to evaluate opportunities for the commercialization of smart insole. smart technology is evolving to Insole. Pressure-sensitive sensor or an acceleration sensor is applied to create a balance of the feet and body, is also evolving for entertainment (sports, entertainment, etc.) and health care. Moreover, smart insole can fix an incorrect walking habit by sending a weight value measured by the sensor on a smartphone and during the movement, smart insole helps to correct body balance by measuring the center of gravity moving condition. However, smart tendency of the insole has yet to create a clear boundary in the entertainment and healthcare markets. This is because the fitness band, smart socks, smart shoes can also replace the benefits of a smart insole. Interestingly, the business opportunities are appearing more frequently in health care solution service of electrocardiogram, body temperature, blood pressure, etc., rather than smart devices.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4411-4417
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• 2015

The proper design of the gate location for injection molding of plastic goods is obtained from three-dimensional injection molding analysis for various design alternatives. This paper is study on effect of gate location in injection molding. It have a decisive impact on productivity and quality of plastic goods. This objectives of this paper is to analysis effect of hot runner gate location for resin filling, weld line, injection pressure to manufacture of automobile air cleaner upper case with injection molding machine. Thus, to analysis these problems in this paper, location of gate are gave variety in 4 CASEs. In this paper, the CAE simulation considering each variations in location of gate is performed to predict the cause of faulty which appears in the injection molding process.

• Journal of the Korean Society for Railway
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• v.11 no.2
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• pp.195-202
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• 2008

The transition area between a bridge and an earthwork is one of the weakest area of track because of the track geometry deterioration caused unequal settlement of backfill of abutment. In case of a ballastless track, the approach slab could be installed to prevent such a phenomenon. But, if there is occurred the inclined displacement on the approach slab by a settlement of the foundation or formation, the track is also under the inclined displacement. And this defect causes reducing the running stability of a vehicle, the riding comfort of passengers, and increasing the track deteriorations by excessive impact force acting on the track. In this study, parametric studies were performed to investigate the displacement limit on the approach slab to avoid such problems. The length and the amount of unequal settlement of approach slab were adopted as parameter for numerical analysis considering vehicle-track interaction. Car body accelerations, variations of wheel force, stresses in rail, and uplift forces induced on fastener clip were investigated. From the result, resonable settlement limit on the end of an approach slab according to slab length was suggested.

• Journal of The Korean Association For Science Education
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• v.24 no.2
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• pp.287-297
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• 2004

In this study, students' understanding of the analogies used for chemical concepts in science textbooks, misconceptions induced by the analogy, and the factors affecting conceptual understanding were investigated. In addition to the tests of field independency and logical thinking ability, tests of students' understanding of concepts and analogies on three states of matter, pressure-volume relation, molecular motion, and changing state depending upon energy were administered. The results revealed that half of the subjects understood the analogies differently from the textbook writers' intention and that students' conceptual understanding was significantly correlated with the degree of understanding on corresponding analogies, field independency, logical thinking ability, and prior achievement of science. The results of analyzing the direct and indirect effects of each variable on conceptual understanding showed that the direct effect of prior achievement was significant and that field independency and logical thinking ability had indirect effects through understanding of analogies and prior achievement of science. The limitations and implications of using analogies in science education were discussed on the basis of the results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.10
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• pp.971-977
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• 2012

It is well known that the performance of a diesel injector is directly related to the power, emission, and fuel consumption of the diesel combustion engine. In this study, the injection response characteristics of CRDi injectors driven by a solenoid coil and a piezoceramic were investigated by using the AMESim simulation code. Some analytical parameters such as the fuel pressure and hole diameter were considered. From this study, it was shown that the piezo-driven injector had a faster response and had better control capability than the solenoid-driven injector. In addition, it was found that the piezo-driven injector can be utilized more effectively in a multiple injection scheme than a solenoid-driven injector.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.3
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• pp.157-162
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• 2011

This study is about implementing wireless transferring system in pre-hospital cardiopulmonary resuscitation(CPR). Also, this study includes monitoring based feedback between patient and hospital to increase the survival rate of emergency patient by developing the performance of cardiopulmonary resuscitation in pre-hospital. It minimizes the loss of flow rate or gastric inflation through the space between the airway and the esophagus, which enables the inspiration-expiration rate to be measured more precisely. Due to these reasons this study applied ET insertion based respiratory sensor to measure flow rate. The main indices of artificial ventilation are justified from minute respiration(V), end-tidal $CO_2(E_TCO_2)$, and tracheal pressure($P_{tr}$). The simulation is performed to verify the bandwidth and delay time of transport network for in-hospital monitoring even as transporting images and voice information simultaneously. The total bandwidth is 815 kbps, and WLAN (IEEE 802.11x) is used as communication protocol. The network load is under 1.5% and the transmit delay time is measured under 0.3 seconds.

• The Korean Journal of Financial Management
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• v.12 no.1
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• pp.129-143
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• 1995

우리 나라의 금융기관들은 금융환경(金融環境)의 급격한 변화 속에서 일대 전환기를 맞고 있다. 대내적으로는 금리자유화를 비롯한 금융자율화(金融自律化)의 추진, 금융산업의 개편 등의 금융구조 조정이 진행되고 있고, 대외적으로는 국내금융시장에 대한 개방압력(開放壓力)이 가중되고 있다. 본 연구의 목적(目的)은 이상의 다양한 금융환경의 변화 중에서 1991년과 1993년에 실시된 1,2단계 금리자유화조치가 은행의 경영위험에 어떠한 영향을 미쳤는지를 증권시장(證券市場)의 반응을 통하여 규명하고자 한다. 구체적으로 일반적인 예상과 같이 금리자유화로 인하여 은행의 위험이 증가하였는지 아니면 금리자유화가 은행의 자금조달과 운용에 있어서 자율성과 유연성을 확보해 주어서 오히려 은행위험을 감소시켰는지를 실증적으로 검증한다. 주가자료를 이용하는 증권시장의 반응을 통한 은행위험의 분석은 은행에 관련된 재무정보를 신속하고 충분히 반영하는 효율적 시장이며 회계자료를 이용하여 은행위험을 추정하는 방법이 부적절하다는 가정하에서 합리화된다. 은행 위험은 은행감독 당국의 관심대상인 총위험과 은행주식 투자자의 관심대상인 체계적 위험의 두요소를 대상으로 한다. 본 연구의 증권시장반응을 통한 실증분석결과에 의하면 금리자유화조치 이후 은행의 위험은 예상과는 달리 증가하지 않은 것으로 나타났다. 은행총위험은 증가하지 않았으며 체계적 위험은 오히려 2차 금리자유화 이후 하락하는 결과를 보여준다. 이는 금리자유화 조치가 은행의 자금조달과 운영에 있어서 운신의 폭을 넓혀줌으로써 금리 변동폭 증대로 인한 위험증가를 상쇄함을 의미한다. 이러한 결과는 미국의 금리자유화조치에 관련된 대부분의 연구결과와 일치한다. 또한 위험은 개별은행의 재무특성에 따라서 상이한 변화를 보여주었다. 특히 자산규모가 작은 후발은행의 경우 자금조달과 운영의 측면에서의 제한이 완화됨으로써 위험이 감소함을 보여준다. 따라서 정부당국자는 금리자유화의 긍정적 효과를 극대화하는 방향으로 적극적으로 금리자유화를 추진하는 것이 바람직하다.

• Journal of the Korean Institute of Gas
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• v.10 no.2 s.31
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• pp.40-46
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• 2006

In this paper, the optimized design of a rectangular O-ring groove has been analyzed for a maximum Cauchy stress and maximum strain using the Taguchi method. This method may efficiently optimize the design parameters for an O-ring groove of a LPG filling unit. The computed FEM results indicate that the optimized design parameters can only be drawn by nine experimental numbers of iterations when the Taguchi design technique has been employed with a finite element method. This means that the Taguchi design method is very useful for the optimization design of O-ring rectangular groove geometry. Based on the computed FEM results by the Taguchi design technique, the dimensions of a groove geometry are given as h=2.5 mm, d=2.74 mm, c=0.15 mm, and w=3.0 mm. In this study, the initial compression ratio of O-rings is recommended as 8.7% for a gas supply pressure of 18 $kg/cm^2$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.9-15
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• 2008

Mokumegane is one of the sophisticated metal craft techniques enabling wood grain surface effect. To embody the mokumegane, an ingot of well-bonded stacked metal plates has been required. Traditionally prepared mokumegane ingots were bonded using charcoal which enables reduction atmosphere, but sometimes end up with collapse of bonding interface due to the lack of reliable process control. We proposed a systematic vacuum direct bonding process for ingots. First, we confirmed copper//copper homogeneous plate bonding at $900^{\circ}C$ by applying uniaxial press of 2.5kg. We observed 80min required to obtain 90%-bonding ratio and the diffusion coefficient would be enhanced up to 100 times due to surface effect. Second, by considering enhanced diffusion behavior, we also obtained optimum bonding condition in copper/silver heterogeneous plates that ensures 90%-bonding ratio at $700^{\circ}C$ for 10min with apply uniaxial press. A 7-layered copper/silver ingot is prepared successfully, and eventually the prototype mokumegane cases for mobile phone were fabricated with these ingot.