• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1596-1604
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• 2013

Coordinating operation between large-scale wind power and thermal units in multiple time scale is an important problem to keep power balance, especially for the power grids mainly made up of large coal-fired units. The paper proposes a novel operation mode of multi-scale unit commitment (abbr. UC) that includes mid-term UC and day-ahead UC, which can take full advantage of insufficient flexibility and improve wind power accommodation. First, we introduce the concepts of multi-scale UC and then illustrate the benefits of introducing mid-term UC to the wind-coal intensive grid. The paper then formulates the mid-term UC model, proposes operation performance indices and validates the optimal operation mode by simulation cases. Compared with day-ahead UC only, the multi-scale UC mode could reduce the total generation cost and improve the wind power net benefit by decreasing the coal-fired units' on/off operation. The simulation results also show that the maximum total generation benefit should be pursued rather than the wind power utilization rate in wind-coal intensive system.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1322-1327
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• 2007

Many automotive companies have tried to apply the aluminum alloy sheet to car body because reducing the car weight can improve the fuel efficiency of vehicle. In order to do that, sheet materials require of weldablity, formability, productivity and so on. Aluminum alloy was not easy to join these metals due to its material properties. Thus, the laser is good heat source for aluminum alloy welding because of its high heat intensity. However, the welding quality was not good by porosity, underfill, and magnesium loss in welded metal for AA5182 aluminum alloy. In this study, Nd:YAG laser welding of AA 5182 with filler wire AA 5356 was carried out to overcome this problem. The weldability of AA5182 laser welding with AA5356 filler wire was investigated in terms of tensile strength and Erichsen ratio. For full penetration, mechanical properties were improved by filler wire. In order to optimize the process parameters, model to estimate tensile strength by artificial neural network was developed and fitness function was defined in consideration of weldability and productivity. Genetic algorithm was used to search the optimal point of laser power, welding speed, and wire feed rate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1793-1799
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• 2003

An optimal design of a multi-layered plate structure to endure high-velocity impact has been suggested by using size optimization after numerical simulations. The NET2D, a Lagrangian explicit time-integration finite element code for analyzing high-velocity impact, was used to find the parameters for the optimization. Three different materials such as mild steel, aluminum for a multi-layered plate structure and die steel for the pellet, were assumed. In order to consider the effects of strain rate hardening, strain hardening and thermal softening, Johnson-Cook model and Phenomenological Material Model were used as constitutive models for the simulation. It was carried out with several different gaps and thickness of layers to figure out the trend in terms of those parameters' changes under the constraint, which is against complete penetration. Also, the measuring domain has been shrunk with several elements to reduce the analyzing time. The response surface method based on the design of experiments was used as optimization algorithms. The optimized thickness of each layer in which perforation does not occur has been obtained at a constant velocity and a designated total thickness. The result is quite acceptable satisfying both the minimized deformation energy and the weight criteria. Furthermore, a conceptual idea for topology optimization was suggested for the future work.

• Journal of Radiation Industry
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• v.17 no.4
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• pp.391-396
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• 2023

Currently, state-of-the-art devices such as SPECT, PET/CT, and PET/MRI are rapidly spreading nationwide, and the penetration rate of nuclear medical devices is also ranked fifth in the world. However, PET/MRI's system is slower and less common because it is more complex than PET/CT. The purpose of this study is to provide optimal information on PET/MRI according to the patient's disease. The subjects obtained information on head and neck cancer, pediatric patients, breast cancer patients, heart disease patients, lung cancer patients, and rectal cancer patients. We tried to accumulate protocols by obtaining a lot of information about each disease. In diagnosing head and neck cancer, it is believed that it is highly likely to be used in evaluating preoperative stage determination, recurrence and remote metastasis after treatment, and unclear primary cervical lymph node metastasis. Diagnosis and continuous follow-up of pediatric patients can increase patient benefits by minimizing radiation exposure. Breast cancer provides a comprehensive evaluation of the clinical need to determine the extent of disease in breast and local lymph nodes and the systematic stages of early diagnosis or recurrence. In diagnosing heart disease patients, MR-based PET motion correction helps to realize the full potential of PET images. For lung cancer patients, the clinical value and usefulness of the resolution and detection ability of integrated PET/MRI for soft tissues such as lung cancer will be sufficient. In diagnosing rectal cancer patients, the detection of missing residual diseases can change the clinical response evaluation for rectal cancer patients treated with TNT, and both the initial stage and treatment response evaluation are possible. Therefore, this literature study provided basic clinical data for PET/MRI tests.

• Journal of Korean Society of Transportation
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• v.30 no.6
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• pp.71-80
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• 2012

This research suggested a real-time traffic signal control algorithm using individual vehicle travel times on an isolated signal intersection. To collect IDs and passing times from individual vehicles, space-based surveillance systems such as DSRC were adopted. This research developed models to estimate arrival flow rates, delays, and the change rate in delay, by using individual vehicle's travel time data. This real-time signal control algorithm could determine optimal traffic signal timings that minimize intersection delay, based on a linear programming. A micro simulation analysis using CORSIM and RUN TIME EXTENSION verified saturated intersection conditions, and determined the optimal traffic signal timings that minimize intersection delay. In addition, the performance of algorithm varying according to market penetration was examined. In spite of limited results from a specific scenario, this algorithm turned out to be effective as long as the probe rate exceeds 40 percent. Recently, space-based traffic surveillance systems are being installed by various projects, such as Hi-pass, Advanced Transportation Management System (ATMS) and Urban Transportation Information System (UTIS) in Korea. This research has an important significance in that the propose algorithm is a new methodology that accepts the space-based traffic surveillance system in real-time signal operations.

• Journal of Advanced Marine Engineering and Technology
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• v.13 no.4
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• pp.63-74
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• 1989

It is well-known that the fuel injection system if a diesel engine has taken a more important place in understanding of diesel combustion process with combustion chamber. But a diesel fuel injection system has an assembly of many complex and intricate problems such as the desired rate of injection, secondary injection and injection pump etc., in addition to the atomization for ignition and combustion, the penetration and diestribution for proper utilization of air. The analysis is carried out by simplifing and modeling the injection phenomena and dividing into three parts comprising of fuel injection pump, high pressure pipe and fuel injection nozzle. The purpose of this paper is to describe an analytical simulation of the injection system and to speed up the work of developing injection systems for new engines. The effects of important injection parameters as predicted by the present model are found to be in good agreement with experiment. It can be seen that there is an optimal pipe diameter for maximum quantity injected.

• Journal of ILASS-Korea
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• v.28 no.1
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• pp.16-23
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• 2023

The objective of this numerical study is to investigate the effect of the shape and material of the blower blade for the electrified speed sprayer on the blowing performance. The shape of the blade was changed to the bonding angle, the number of blades, the width of the blade, and the blade length based on the existing model. In order to obtain the reliability of the numerical model, the analysis of the grid dependence was performed in the numerical analysis. The numerical analysis results were compared and analyzed in terms of the agricultural chemical penetration length characteristics, flow uniformity characteristics, and velocity distribution characteristics. Furthermore, the effect of material change on weight reduction and structural characteristics was also compared and analyzed. As a result of the analysis, it was found that the optimal condition was that the blade angle was 45°, the number of blades was 12, and the width was 115 mm, which was confirmed through a comparison of the inlet mass flow rate. As a result of the equivalent stress lower than the yield strength due to the material change from aluminum to steel compared to the existing steel, structural defects do not appear, and it is judged that the operation time compared to the battery capacity will be improved through the weight reduction of the blade.

• Magazine of the Korean Society of Agricultural Engineers
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• v.21 no.3
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• pp.83-91
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• 1979

This study was conducted in order to find out the performance of rice transplanters in accordance with the change of the trans-planting days after pudding and the water depth flooding the paddy field at the time of transplanting : and thus to select the optimum paddy field preparation procedures for an efficient utilization of rice transplanters. The performance factors of the two different types of rice transplanters were measured during the first 6 consecutive days after puddling and with 3 different levels of water depth flooding the paddy fields. The results of this study were analysed and summarized as follows : 1. Wheel sinkage decreased very rapidly from 0 to 2 days after puddling and slowly from 3 to 5 days after puddling. 2. The depth of the test cone penetration decreased rapidly during the first few days after puddling. It was 17.8cm just after puddling, and decreased to 13.4cm one day after puddling. After 2 days, the rate of decrease was dampened, and after 5 days it kept constant value of 9.2cm. 3. Two days after puddling, the hill interval was 15.8cm (98.75% of the preset value) for broadcasted seedling rice transplanter with 3cm flooding depth : This value was the closest to the pre-adjusted value of 16cm. The general performance of broadcasted-seedling type rice transplanter was better than that of strip-seedling type rice transplanter. 4. Usually the working performance of a rice transplanter is evaluated with uniformity and adjustability of the hill intervals. The hill interval was the most uniform and closest to the pre-set value of 16cm when planted two days after puddling with 3cm of water depth. When it was inavoidable to plant 4 days after puddling with stripseedling type rice transplanter, it is advisable to let the water flooded somewhat deeper. 5. The percentage of missing hills including floating and burried seedlings was the highest just after puddling and ie decreased substancially until 3 days after puddling and then it increased again. Hence, the optimal time transplanting is to be between 2 and 3 days after puddling. 6. Better postures of planted seedlings were found when planter 2 days after puddling than 3 days after puddling. Six cm of flooding water depth always gave the best results with respect to the postures of planted seedlings. Broadcasted-seedling rice transplanter, in general, showed better posture of planted seedlings than did strip-seedling type rice transplanter. 7. Judging from the above results, the optimal conditions will be 3cm of flooding depth and transplanting between 2 and 3 days after puddling.

• Knowledge Management Research
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• v.21 no.3
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• pp.105-121
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• 2020

With regard to the development of new drugs, what is most important for a Korean Biotech, where no global sales network has been established, is decision-making related to out-licensing of new drugs. The probability of success for each clinical phase is different, and the licensing amount and its royalty vary depending on which clinical phase the licensing contract is made. Due to the nature of such a licensing contract and Biotech's weak financial status, it is a very important decision-making issue for a Biotech to determine when to license out to a Big Pharma. This study defined a model called 'optimal timing for out-licensing of new drugs' and the results were derived from the decision tree analysis. As a case study, we applied to a Biotech in Korea, which is conducting FDA global clinical trials for a first-in-class new drug. Assuming that the market size and expected market penetration rate of the target disease are known, it has been shown that out-licensing after phase 1 or phase 2 of clinical trials is a best alternative that maximizes Biotech's profits. This study can provide a conceptual framework for the use of management science methodologies in pharmaceutical fields, thus laying the foundation for knowledge and research on out-licensing of new drugs.

• Korean Journal of Agricultural Science
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• v.23 no.2
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• pp.206-211
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• 1996

This study was conducted to investigate the effects of medium and cumulus cell on in vitro fertilization of porcine follicular oocytes. The results obtained are as follows ; 1. The normal fertilization rates of in vitro matured follicular oocytes cultured in 00, mT ALP and TCM-HEPES medium were 14.0~24.3%, 30.8~32.7% and 21.4~23.9%, respectively. These data indicated that the optimal medium for fertilization of porcine oocytes in vitro was the mTALP medium 2. The normal fertilization rates of epididymal sperm were 24.3%(80), 30.8%(mTALP) and 23.9%(TCM-HEPES), and those of ejaculated sperm were 14.0%(B0), 32.7%(mTALP) and 21.4%(TCM-HEPES). 3. The sperm penetration rates of cumulus-enclosed and cumulus-free oocytes on in vitro fertilization were 54.0% and 72.0%. The normal fertilization rates of cumulus-enclosed and cumulus-free oocytes were 11.9% and 21.5%. The normal fertilization rate of cumulus-enclosed oocytes was significantly(P<0.05) higher than that of cumulus-free oocytes.