• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.4
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• pp.159-167
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• 1985

It was demonstrated that the glottal waves are different depending on a kind of vowels in deriving the glottal waves directly from Korean vowels/a, e, I, o, u/ w, ch are recorded by a male speaker. After resynthesizing vowels with five simulated glottal waves, the effects of glottal wave shape on the speech synthesis were compared with in terms of waveform. Some changes could be seen in the waveforms of the synthetic vowels with the variation of the shape, opening time and closing time, therefore it was confirmed that in the speech sysnthesis, the glottal wave shape is an important factor in the improvement of the speech quality.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.12
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• pp.81-90
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• 1994

This paper proposes a motphological fast reconstructive filter (FRF) using up/down sampling techniques for reconstructive opening and closing, and a parallel structure for fast multiresolution decomposition. Compuer simulation shows that, compared with the conventional RF, the proposed FRF can reduce the processing time up to 8 times while it maintains a similar performance in reconstructed shapes. Further reduction in the decomposition time achieved by the paralellized algorithm combined with the FRF, which can be applied in areas such as defect detection, image segmentation, pattern recognition, etc.

• Journal of the Korean Institute of Gas
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• v.3 no.1
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• pp.58-63
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• 1999

Experimental works were carried out to evaluate how the lapse of time affects the performance characteristics and the service life of low pressure LPG regulators for domestic use. Experimental results showed that the operating pressure of safety devices deviated from the opening pressure value and the closing pressure value from just 1 year after service, and the operating pressure of regulators used for 7${\~}$8 years notably deviated from the reference value of the adjusting pressure and the closing pressure. And the material properties of springs and diaphragms deteriorated after 5${\~}$6 years of service. Thus, it is estimated that low pressure LPG regulators have approximately 6 years of service life. However, it is highly recommended that regulators exceeding 5 years of service should be replaced for the safety of consumer and accident prevention even if they are operating normally.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.3
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• pp.427-452
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• 1998

To elucidate the effects of food texture such as hardness, cohesiveness, adhesiveness on mastication procedure, the electromyographic activity (EMG) of the masticatory muscles and the chewing movements were analyzed in eighteen young subjects during ordinary chewing. Seven different foods were selected by sensory texture profiling and mechanical test with texturometer; egg white, sausage, pizza cheese, yang-geng, biscuit, peanut and almond. The indexes of jaw movements used were the chewing number, chewing time, maximum opening, average opening, closing velocity and opening velocity. The EMG indexes analyzed were maximum and average integrated amplitude of the anterior temporal and masseter muscles. The results obtained were as follows. 1. The chewing time and chewing number, mandibular displacement and mandibular movement velocity were not changed by the hardness, cohesiveness and adhesiveness of the food (p>0.05). 2. The harder food materials showed a higher amplitude of the anterior temporal muscle integrated EMGs than the softer ones (p<0.05). 3. The maximum and average integrated EMGs of the masseter muscle increased with the increase of hardness of the food (p<0.05). 4. The integrated EMGs of preferred side and non-preferred side masticatory muscles increased with the increase of hardness of the food (p<0.05). 5. The adhesiveness and cohesiveness of the food were not the determining factor to the integrated EMGs of masticatory muscles (p<0.05).

• The Korean Journal of Applied Statistics
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• v.23 no.5
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• pp.823-834
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• 2010

Stock markets perpetually accumulate information. During trading hours the price instantaneously reacts to new information, but accumulated overnight information reacts simultaneously on the opening price. This can create opening price uctuations. This study explores the overnight information e ects on intra-da stock market volatility. GARCH models and the VKOSPI model are provided. Empirical data includes daily opening and closing prices of the KOSPI 200 index and the VKOSPI from March $3^{rd}$ 2008 to June $22^{th}$ 2010. Empirical results show that the VKOSPI signi cantly decrease during trading time when positiv overnight information moves the Korean stock upward. This study provides useful information to investors since the Korea Exchange plans to introduce a futures market for the VKOSPI soon.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.741-747
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• 2010

Vent-relief valve performed as a safety-valve combination for liquid propellant feeding system of space launch vehicle, which can vent the vaporized oxygen vapor during both filling cryogenic oxidizer into tank and flight. We have designed vent-relief model by using the AMESim code to predict dynamic characteristics and simulate pneumatic behavior of valve. To validate valve model we have compared by opening time in vent model, and opening/closing pressure by mathematical methods and improved the accuracy through numerical flow analysis by using FLUENT code. In this study, we had verified design parameters and analyzed operating performances. We can use these analysis results to precedent development study on propellant feeding system of Korea Space Launch Vehicle.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.3
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• pp.335-341
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• 2011

In this paper, we proposed an automatic packing mechanism of one station concept for fastener objects where the continuous work is performed in a finite space. The proposed packing mechanism is composed of supporting frame, feeding supply, air shower device, clamping/opening device, batch charging device, sealing/cutting device and supply adjusting device. And, these mechanisms have been modularized through mechanical, dynamical, structural and fluid optimized design using the SMO(SimDesigner Motion) analysis module. Also, the virtual prototype was carried out using the 3-D CAD program. The packing process is consisted performed in the order of feeding, clamping, bottom sealing, cutting, opening, object charging, closing and the upper sealing. And the time of these cycles were designed to be completed in 15-20 seconds. This packing mechanism will be created as a prototype in the near future. In addition, it will be applied to the production scenes after going through a field test for the validation of performance.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.146-146
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• 2021

A contamination event occurring in water distribution networks (WDNs) needs to be handled with the appropriate mitigation strategy to protect public health safety and ensure water supply service continuation. Typically the mitigation phase consists of contaminant sensing, public warning, network inspection, and recovery. After the contaminant source has been detected and treated, contaminants still exist in the network, and the contaminated water should be flushed out. The recovery period is critical to remove any lingering contaminant in a rapid and non-detrimental manner. The contaminant flushing can be done in several ways. Conventionally, the opening of hydrants is applied to drain the contaminant out of the system. Relying on advanced information and communication technology (ICT) on WDN management, warning and information can be distributed fast through electronic media. Water utilities can inform their customers to participate in the contaminant flushing by opening and closing their house faucets to drain the contaminated water. The household draining strategy consists of determining sectors and timeslots of the WDN users based on hydraulic simulation. The number of sectors should be controlled to maintain sufficient pressure for faucet draining. The draining timeslot is determined through hydraulic simulation to identify the draining time required for each sector. The effectiveness of the strategy is evaluated using three measurements, such as Wasted Water (WW), Flushing Duration (FD), and Pipe Erosion (PE). The optimal draining strategy (i.e., group and timeslot allocation) in the WDN can be determined by minimizing the measures.

• Journal of the korean society of oceanography
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• v.32 no.1
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• pp.38-45
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• 1997

To find out the changes in vertical distribution patterns over the 24-h period, a key and the first step to tackle the problem of adaptive significance of diel vertical migration (DVM), vertically stratified time series samplings with multiple opening/closing plankton samplers were done in the East Sea of Korea (Sea of Japan). Sampling was done almost every 4 h for one day period following the same water parcel in Nov. 1995 and May 1996, respectively. Resultant patterns of vertical distribution showed that some species such as most abundant taxa Metridia pacifica and Scolecithyicella minor, both Copepoda, performed DVM even in the study area of strong thermal stratification. Their patterns of DVM such as distance scales and timing of movements were not the same each other, and they were separated from other taxa in the dendrogram obtained by the cluster analyses, Most minor taxa grouped in one, however, seemed not to do DVM in the study area of strong thermal stratification. They usually preferred the warmer surface layer where the foods were probably more abundant.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.777-781
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• 1997

One of the spring-link mechanisms, the air circuit breaker(ACB), was studied to improve the shock-proof characteristics of it. The low-cycle fatigue fracture phenomenon was occurred on the critical link, called h-link, of ACB for the repeated rapid closing and opening operations. To analyze the cause of failure, dynamic FE-analysis on the h-link part of ACB was accomplished with considered the velocity and acceleration of the links per time as boundary conditions, which were obtained by using ADAMS. Then, to reduce the maximum tensile stress on the h-link, three types of h-link were suggested and one of them was selected. Fmm this study, we suggested the process of analysis on the high-speed motion behavior part related low-cycle fatigue fractures.