• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.116-122
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• 2014

In this study, 2 kinds of twist run models as exercise equipments are compared by durability analyses of fatigue and vibration. Maximum equivalent stresses are shown as 3.3 MPa and 16.6 MPa at the parts of stress concentrations at models 1 and 2. As the values becomes much lower than yield stress of this models, these models are shown to be safe designs. Model 1 becomes stronger than model 2 at natural frequency analysis. Fatigue lives become lowest at four axis parts and one axis part respectively in cases of models 1 and 2. Maximum damage probability at fatigue is shown to be 2.4% near the average stress of 0 in case of model 1 but this probability becomes 0.6 % in case of model 2. Model 1 has the maximum damage possibility 4 times more than model 2 at these states. As the result of this study is applied by the design of twist run, the prevention on fatigue damage and the durability are predicted.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.199-202
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• 2005

High speed milling process is emerging as an important fabrication process benefits include the ability to fabricate micro and meso-scale parts out of a greater range of materials and with more varied geometry. It also enables the creation of micro and meso-scale molds for injection molding. Factors affecting surface roughness have not been studied in depth for this process. A series of experiments has been conducted in order to begin to characterize the factors affecting surface roughness and determine the range of attainable surface roughness values for the high speed milling process. It has previously been shown that run-out creates a greater problem for the dimensional accuracy of parts created by high speed milling process. And run-out also has a more significant effect on the surface quality of milled parts. The surface roughness traces reveal large peak to valley variations. This run-out is generated by spindle dynamics and tool geometry. In order to investigate the relationship between tool setting errors and surface roughness end tilted mills were used to cut aluminum samples. The results indicate that tool setting errors have significant effects on surface roughness and cutting forces.

• Journal of the Korean association of regional geographers
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• v.12 no.6
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• pp.748-756
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• 2006

This study mainly deals with price behavior developed in a agricultural location model (or closed model) considering the production and demand aspects. The short-run situation of price and output is associated with the yearly fluctuation of yield from agricultural production. Demand is generally regarded as constant in the short-run because of being inelastic over short time. The long-run situation is associated with a period in which all related variables can be varied. Then a price behaviors from the two contrasting closed models have been further explored in the long-run economy. Agricultural price for each activity in the closed model is affected by change in agricultural production. Also, falling agricultural price is connected with lower rents and lower land values.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.627-628
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• 2006

High speed milling process is emerging as an important fabrication process benefits include the ability to fabricate micro and meso-scale parts out of a greater range of materials and with more varied geometry. It also enables the creation of micro and meso-scale molds for injection molding. Factors affecting surface roughness have not been studied in depth for this process. A series of experiments has been conducted in order to begin to characterize the factors affecting surface roughness and determine the range of attainable surface roughness values for the high speed milling process. It has previously been shown that run-out creates a greater problem for the dimensional accuracy of pans created by high speed milling process. And run-out also has a more significant effect on the surface quality of milled parts. The surface roughness traces reveal large peak to valley variations. This run-out is generated by spindle dynamics and tool geometry. In order to investigate the relationship between tool alignment errors and surface roughness the scallop generating mechanism in the ball-end milling with tool alignement errors has been studied and simulated. The results indicate that tool alignment errors have no significant effects ell the dimension of scallops in for flat planes.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.2
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• pp.131-137
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• 2016

Purpose : The bladder volume change was measured using ultrasonography for helping decrease the side effects and other organ variations in the location of radiation therapy for cervical cancer patients. An experiment was performed targeting patients who were treated with radiation therapy at PNUH within the period from September to December 2015. Materials and Methods : To maintain the bladder volume, each patient was instructed to drink 500 cc water before and after CT simulation, 60 minutes before the dry run. Also, the bladder volume was measured in each patient CT scan, and a 3D conformal therapy plan was designed. The bladder volumes measured before and after the CT simulation, dry run, and radiation treatment planning were compared and analyzed. Results : The average volume and average error of the bladder that were obtained from the measurement based on the CT scan images had the lowest standard deviation in the CT simulation. This means that the values that were obtained before and after the CT simulation were statistically relevant and correlative. Moreover, the bladder volume measured via ultrasonography was larger size, the average volume in the CT scan. But the values that were obtained Dry run and after the CT simulation were not statistically relevant. Conclusion : Drinking a certain amount of water helps a patient maintain his/her bladder volume for a dry run. Even then, it is difficult to maintain the bladder volume for the dry run. Also, whether or not the patients followed the directions for the dry run correctly is important.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.9
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• pp.828-833
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• 2011

A reaction wheel assembly(RWA) is the largest disturbance source that can induce high frequency micro-vibration on an optical payload of satellites. To ensure a tight pointing-stability budget of satellites, the RWA disturbance effect on spacecraft should be accurately analyzed and evaluated for whole design phases. For this purpose, the micro-vibration disturbance of RWA should be precisely measured. In the present study, two measurement methods on RWA micro-vibration disturbances are compared and investigated. One is a free run-down speed test and the other is a constant speed test. The micro-vibration data measured by the two methods are analyzed in terms of spectrum characteristics, static and dynamic imbalance values, and root sum square(RSS) values. The analysis results show that both methods can measure very similar results in time and frequency domains and that the free run-down speed method is more adequate in respects to wheel friction modeling, noise rejection of imbalance and RSS peak evaluation.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.211-217
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• 2014

A new needle-based device for headspace wire coated in-needle microextraction (HS-WC-INME) was fabricated using a nichrome wire coated with poly(ethylene glycol) (PEG) and poly(dimethylsiloxane) (PDMS) mixture. The proposed needle device was applied for the determination of volatile compounds in lavender and lavandin essential oils by gas chromatography. Fundamental parameters such as needle design, conditions of extraction and desorption were optimized along with the validation of the extraction and desorption efficiency. The optimal conditions were 30 min extraction at $50^{\circ}C$ and 2 min desorption at $240^{\circ}C$. The calibration curves showed good linearity with the suitable values of the coefficients of determination ($r^2$) greater than 0.99. The limits of detection for linalyl acetate, ${\beta}$-caryophyllene, linalool and (+)-limonene were 7.15, 9.04, 10.79 and 22.26 ng, respectively. Analytical recoveries were acceptable in the test samples, varying from 86.7% to 108.0%. The values of relative standard deviations for run to run showed range less than 0.9% while 3.9% through 7.2% for needle to needle. The proposed PEG-PDMS coating could be more suitable than PDMS coating to extract particular polar groups such as alcohols.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.277-292
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• 2018

This paper presents the development and implementation of an artificial intelligence (AI)-based deep excavation induced wall and ground displacements and wall support member forces prediction program (ANN-EXCAV). The program has been developed in a C# environment by using the well-known AI technique artificial neural network (ANN). Program used ANN to predict the induced displacement, groundwater drawdown and wall and support member forces parameters for deep excavation project and run the stability check by comparing predict values to the calculated allowable values. Generalised ANNs were trained to predict the said parameters through databases generated by numerical analysis for cases that represented real field conditions. A practical example to run the ANN-EXCAV is illustrated in this paper. Results indicate that the program efficiently performed the calculations with a considerable accuracy, so it can be handy and robust tool for preliminary design of wall and support members for deep excavation project.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.5
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• pp.1-9
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• 2022

The study examines stock prices (LOGKSE) and exchange rate (LOGPK)-Pakistani Rupee vis-à-vis US Dollar- interactions in Pakistan. This study employs a multivariate VAR-GARCH model using monthly data from January 2012 to October 2020. The results of the Johansen cointegration test show that there is no relationship between Foreign Exchange Market and Stock Market in the long run. In the short-run, stock exchange returns are affected slightly negatively by the changes in the foreign exchange market, but the foreign exchange market does not seem to be affected by the ups and downs of the stock exchange. The VAR model and Granger Causality show that both markets are strongly influenced by their own lagged values rather than by the lagged values of one another and show weak or no correlation between the two markets. Volatility persistence is observed in both the stock and foreign exchange markets, implying that shocks and past period volatility are major drivers of future volatility in both markets. Thus greater uncertainties today will induce panic and consequently generate higher volatility in the future period. This phenomenon has been observed many times on Pakistan Stock Exchange especially. The results have important implications for local international investors in portfolio diversification decisions and risk hedging strategies.

• Journal of the Korean Society for Railway
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• v.8 no.4
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• pp.354-360
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• 2005

The railway track and the substructures constructed in the field test section of Kyongbu High Speed Line are the structures for HSL, for the first time designed and constructed by domestic technical group. It is very important to verify the local design criteria and specifications for these structures and also to assure the recordings for vibration or deflection produced on the essential parts of the structures. The study to verify the high-speed railway track performance and to ensure the run in safety on the track in curved section during the KTX run. Finally, the conclusion are drawn as follows. The measuring values of the deflection effort of the rail and displacement for verifying the track performance in the field test section of Kyoungbu HSL satisfy the criteria of the foreign countries (Japan and Germany). The measured value for the wheel load and the presumed value show the consistent tendency. The wheel loads of the exterior and interior of the rails at the speed superior to 300km/h are measured same. Finally, the comparison between the theoretical value presented during the verification of the derailment to evaluate the safety of the train run at the time of the detailed design of the track and the measured value in the field shows that the correct design of track structure was applied.