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Ternary Forecast of Heavy Snowfall in the Honam Area, Korea

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Advances in Atmospheric Sciences 2009年第2期26卷 327-332页

作者： Keon Tae SOHN Jeong Hyeong LEE young seuk CHO Department of Statistics Pusan National University Division of Management Information Science Dong-A University

The objective of this study is to improve the statistical modeling for the ternary forecast of heavy snowfall in the Honam area in Korea. The ternary forecast of heavy snowfall consists of one of three values, 0 for less than 50 mm, 1 for an advisory （50-150 ram）, and 2 for a warning （more than 150 mm）. For our study, the observed daily snow amounts and the numerical model outputs for 45 synoptic factors at 17 stations in the Honam area during 5 years （2001 to 2005） are used as observations and potential predictors respectively. For statistical modeling and validation, the data set is divided into training data and validation data by cluster analysis. A multi-grade logistic regression model and neural networks are separately applied to generate the probabilities of three categories based on the model output statistic （MOS） method. Two models are estimated by the training data and tested by the validation data. Based on the estimated probabilities, three thresholds are chosen to generate ternary forecasts. The results are summarized in 3 × 3 contingency tables and the results of the three-grade logistic regression model are compared to those of the neural networks model. According to the model training and model validation results, the estimated three-grade logistic regression model is recommended as a ternary forecast model for heavy snowfall in the Honam area.

关键词： ternary forecast of heavy snow MOS multi-grade logistic regression neural networks threshold

Analysis and optimization of nitrile butadiene rubber sealing mechanism of ball valve

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中国有色金属学会会刊：英文版 2009年第B09期19卷 220-224页

作者： young-Chul park Department of Mechanical Engineering Dong-A University

An approach for analyzing and optimizing sealing mechanism of ball valve made of nitrile butadiene rubber(NBR) with finite element method was presented. The Mooney-Rivlin hyperelastic material model was chosen to characterize NBR sealing, as it has been recommended in the similar applications. That is, NBR sealing was modeled as incompressible hyperelasticity, as well as the assumption of isotropic flow. The results illustrate the structural pressure and contact pressure on the contact surface, which shows that the NBR sealing mechanism is very suitable for sealing after dimension optimization.

关键词：橡胶密封丁腈橡胶尺寸优化机制球阀有限元方法材料模型各向同性

The Study on Effect of Exhaust Performance According to Active Muffler Valve Spring as Followed Spring Constant

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Journal of Thermal Science 2002年第4期11卷 372-377页

作者： seuk Cheun Choi Tae Woo Kong Han Shik Chung Hyo Min Jeong young Heung Chun Graduate School of Mechanical and Precision Engineering Gyeongsang National UniversityInpyeongdong 445 Tongyong Kyongnam 650-160Korea School of Transport Vehicle Engineering Gyeongsang National UniversityThe Institute of Marine IndustryInpyeongdong 445 Tongyong Kyongnam 650-160Korea

This study represents the influence on exhaust performance by active muffler valve *** main experimental parameters were engine speeds and torsion coil spring constants in the active *** the muffler valve spring has a low spring constant of k=0.75,the sound pressure level was low at the region of engine speed 2000 to 2500 r/min,and the velocity of exhaust gas was high at spring constant k=*** the engine speed was under 1500 r/min,the mean concentration of CO was high in case without muffler *** the engine speed in the range of 1600 to 2600 r/min with spring constant k=0.75,the mean HC concentration showed the lowest *** muffler valve,the temperature in the muffler was higher than the case with muffler *** research represented that the performance of the active muffler valve spring constant k=0.75 was higher than that without muffler valve and valve spring constant k=*** the three cases of experimental condition,with a spring constant k=0.75,0.70 and without muffler valve,the exhaust performance was high in case active muffler valve spring constant k=0.70.

关键词： active muffler torsion coil spring spring constant sound pressure level

Effects of Nitrogen Source and Bacterial Elicitor on Isoflavone Accumulation in Root Cultures of Albizzia kalkora （Roxb.） Prain

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Journal of Integrative Plant Biology 2006年第9期48卷 1108-1114页

作者： So-young park Wi-young Lee youngki park Jin-Kwon Ahn Biotechnology Division Korea Forest Research Institute Suwon 441-350 Korea

Changes in cellular isoflavone （daidzein and genistein） contents were monitored in root cultures of Albizzia kalkora （Roxb.） Prain after feeding different ratios of NH4^＋/NO3^- and treatment with a biotic elicitor （three strains of Rhizobium sp.）. The NH4^＋/NO3^- ratio appears to be positively correlated with daidzein content in the roots and shows a negative correlation with genistein. Among the three different strains of Rhizobium used, the strain ATCC 15834 caused a 35% increase in daidzein production by infection. In the case of genistein, maximum production （94%） was obtained when cultures were treated on Day 6 by the strains ATCC 15834 and KCTC 1541. The biosynthetic pathway of the two isoflavones apparently reacts differently to the same culture conditions and the same strains of Rhizobium. Therefore, the present data suggest that the production of daidzein and genistein could be modulated by changing the NH4^＋/NO3^- ratio and the application of Rhizobium.

关键词： Albizzia kalkora infection isoflavone nitrogen root culture

Weldability evaluation and tensile strength estimation model for aluminum alloy lap joint welding using hybrid system with laser and scanner head

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中国有色金属学会会刊：英文版 2012年第S3期22卷 596-604页

作者： Dong-Yoon KIM young-Whan park Department of Mechanical Engineering Pukyong National University

Aluminum welding using a hybrid system with a laser and scanner welding head was performed under various welding conditions to verify the feasibility of applying an aluminum alloy to a car *** experimental material was 5J32 aluminum alloy,and the laser power,welding speed,and laser incidence angle were used as the control *** weld bead shape and the tensile shear strength were evaluated in order to understand the aluminum lap joint weld *** of variance (ANOVA) was conducted to identify the effect of the process variables on the tensile shear *** strength estimation models using three different regression models were also *** input variables were the laser power,welding speed,and laser incidence angle,and the output was the tensile shear *** the models,the second-order polynomial estimation model had the best estimation performance,and the average error rate of this model was 0.058.

关键词： laser welding scanner remote welding 5J32 aluminum alloy regression model

OPTIMUM ORDERING POLICY FOR PREVENTIVE AGE REPLACEMENT

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Journal of Systems Science and Systems Engineering 2009年第3期18卷 283-291页

作者： young T. park Jing SUN Department of Systems Management Engineering Sungkyunkwan University School of Economics and Management Tsinghua University Beijing 100084 China

Most of the spare ordering policies treated up to now have assumed that preventive and corrective replacement costs are equal, which implies in essential that there is no significant need for preventive replacement. This paper presents an ordering policy for preventive age replacement with minimal repair. Introducing the replacement, repair, inventory holding and shortage costs, the expected cost rate is derived. A procedure to determine jointly the ordering time for a spare and the preventive replacement time for the operating unit so as to minimize the expected cost rate is proposed. To explain the ordering policy and the optimization procedure, a numerical example is also included.

关键词： Ordering policy spare age replacement minimal repair

Liquid crystal between two distributed Bragg reflectors enables multispectral small-pitch spatial light modulator

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Light(Science & Applications) 2022年第8期11卷 1643-1645页

作者： Junghyun park Kanghee Won young Kim Advanced Sensor Lab Device Research CenterSamsung Advanced Institute of TechnologySuwonRepublic of Korea

The ability of controlling the phase of light at the subwavelength scale can be a game-changer due to its extraordinally wide angle-range in the wavefront shaping. By combining two conventional material and configurat... 详细信息

关键词： crystal enable light

Effect of Ni and Mn on the Mechanical Properties of 22Cr Microduplex Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2015年第1期28卷 32-38页

作者： Jun-young park Yong-Sik Ahn Department of Materials Science and Engineering Pukyong National University

The tensile properties of 22Cr–2Ni–4Mn–0.2N micro-duplex stainless steels with different Ni and Mn contents were investigated. Duplex stainless steels were vacuum induction melted and hot rolled, then annealed at 1,000–1,100 °C, at which temperature both the austenite and ferrite phases were stable. The volume fraction of the ferrite phase was markedly affected by the alloying elements of Mn and Ni; 1 wt% of Mn was equivalent to 0.4 wt% of Ni. All of the steels tested at room temperature showed the common strain-hardening behavior, while the steels tested at lower temperatures（-30 or-50 °C）showed a distinct inflection point in their stress–strain curves, which resulted from the transformation of the austenite to straininduced martensite. The onset strain（e0） of the inflection point in the stress–strain curve depended on the Md30 value of the steel. Testing at lower temperatures resulted in smaller e0 and consequently higher strengths and fracture strains（ef）. The tensile behavior was examined from the perspective of austenite stability of the micro-duplex stainless steels with the different Ni and Mn contents.

关键词： Duplex stainless steel Microstructure Mechanical property Alloy composition

Biomimetic Quadruped Robot with a Spinal Joint and Optimal Spinal Motion via Reinforcement Learning

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Journal of Bionic Engineering 2021年第6期18卷 1280-1290页

作者： young Kook Kim Woojin Seol Jihyuk park LV R&D Team Electro-technology R&D CenterLS Electric Co.LtdCheongju28437Republic of Korea Digital Innovation Unit Korea Hydro&Nuclear Power Co.Ltd1312-gil YuseongdaeroYusung-guDaejeon34101Republic of Korea Department of Automotive Engineering College of Mechanical and IT EngineeringYeungnam University280 Daehak-roGyeongsanGyeongbuk38541Republic of Korea

Feline animals can run quickly using spinal joints as well as the joints that make up their four *** paper describes the development of a quadruped robot including a spinal joint that biomimics feline *** developed robot platform consists of four legs with a double 4-bar linkage type and one simplified rotary *** addition,Q-learning,a type of machine learning,was used to find the optimal motion profile of the spinal *** bounding gait was implemented on the robot system using the motion profile of the spinal joint,and it was confirmed that using the spinal joint can achieve a faster Center of Mass(CoM)forward speed than not using the spinal *** the motion profile obtained through Q-learning did not exactly match the spinal angle of a feline animal,which is more multiarticular than that of the developed robot,the tendency of the actual feline animal spinal motion profile,which is sinusoidal,was similar.

关键词： Quadruped robot system Bioinspired methods Legged robots Machine learning Q-learning