• The Journal of the Korea Contents Association
• /
• v.14 no.2
• /
• pp.467-474
• /
• 2014

The relative dose calculated by MCNPX and the relative dose measured by ionization chamber and solid phantoms evaluated the accuracy comparing with Monte Carlo simulation. In order to apply Monte Carlo simulation the intraluminal brachytherapy of extrahepatic bile duct cancer, 192Ir sealed radioactive source replicate, Bile duct and surrounding organs were made using KMIRD phantom based on a South Korea standard man. To check the absorbed dose of normal organs around bile duct, we set the specific effective energy and initial radioactivity to 1 Ci using MCNPX. Evaluation of the accuracy of the Monte Carlo simulation, the difference of the relative dose is the most 1.96% that satisfy the criteria that is the relative error less than 2% suggested by MCNPX code. In addition, The specific effective energy and absorbed dose of normal organs that were relatively adjacent to bile duct such as right side of kidney, liver, pancreas, transverse colon, spinal cord, stomach and small intestine were relatively high. on the contrary, the organs that were relatively distant to bile duct such as left side of kidney, spleen, ascending colon, descending colon and sigmoid colon were relatively low.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.6
• /
• pp.593-599
• /
• 2016

Incheon Bridge is 13.38 km long with an 800 m span, connecting Incheon International Airport and Songdo International City, Per hour 73.8 vessels navigate this space. The purpose of this study was to suggest a safe passing speed based on the displacement of a vessel based on the safety criteria of Incheon Bridge's anti-collision fence, which was designed during its initial construction. As AASHTO LRFD suggested, vessel collision energy, vessel collision velocity, and the hydrodynamic mass coefficient were considered to derive a safe vessel traffic speed. Incheon Bridge's anti-collision fence was designed so that 100,000 DWT vessels can navigate at a speed of 10 knot. This research suggests a safe speed for vessel traffic through a comparative analysis of an experimental ship's (300,000 DWT) speed and cargo conditions, regulation speed has been calculated according to the collision energy under each set of conditions. Additionally, safe traffic vessel's safe speed was analyzed with reference to tidal levels. Results from the experimental ship showed that a vessel of maximum 150,000 DWT is able to pass Incheon Bridge at a maximum of 7 knots with an above average water level, and is able to pass the bridge with a maximum of 8 knots under ballast conditions.

• Asian-Australasian Journal of Animal Sciences
• /
• v.30 no.1
• /
• pp.34-41
• /
• 2017

Objective: Two experiments were performed to evaluate the effects of coated slow-release urea on nutrient digestion, ruminal fermentation, nitrogen utilization, blood glucose and urea concentration (Exp 1), and average daily gain (ADG; Exp 2) of steers. Methods: Exp 1: Eight ruminally fistulated steers [$503{\pm}28.5kg$ body weight (BW)] were distributed into a d $4{\times}4$ Latin square design and assigned to treatments: control (CON), feed grade urea (U2), polymer-coated slow-release urea A (SRA2), and polymer-coated slow-release urea B (SRB2). Dietary urea sources were set at 20 g/kg DM. Exp 2: 84 steers ($350.5{\pm}26.5kg$ initial BW) were distributed to treatments: CON, FGU at 10 or 20 g/kg diet DM (U1 and U2, respectively), coated SRA2 at 10 or 20 g/kg diet DM (SRA1 and SRA2, respectively), and coated SRB at 10 or 20 g/kg diet DM (SRB1 and SRB2, respectively). Results: Exp 1: Urea treatments (U2+SRA2+SRB2) decreased (7.4%, p = 0.03) the DM intake and increased (11.4%, p<0.01) crude protein digestibility. Coated slow-release urea (SRA2+-SRB2) showed similar nutrient digestibility compwared to feed grade urea (FGU). However, steers fed SRB2 had higher (p = 0.02) DM digestibility compared to those fed SRA2. Urea sources did not affect ruminal fermentation when compared to CON. Although, coated slow-release urea showed lower (p = 0.01) concentration of $NH_3-N$ (-10.4%) and acetate to propionate ratio than U2. Coated slow-release urea showed lower (p = 0.02) urinary N and blood urea concentration compared to FGU. Exp 2: Urea sources decreased (p = 0.01) the ADG in relation to CON. Animals fed urea sources at 10 g/kg DM showed higher (12.33%, p = 0.01) ADG compared to those fed urea at 20 g/kg DM. Conclusion: Feeding urea decreased the nutrient intake without largely affected the nutrient digestibility. In addition, polymer-coated slow-release urea sources decreased ruminal ammonia concentration and increased ruminal propionate production. Urea at 20 g/kg DM, regardless of source, decreased ADG compared both to CON and diets with urea at 10 g/kg DM.

• The Journal of Korean Medicine
• /
• v.41 no.2
• /
• pp.58-79
• /
• 2020

Objectives: The purpose of this study is to predict the weight loss by applying machine learning using real-world clinical data from overweight and obese adults on weight loss program in 4 Korean Medicine obesity clinics. Methods: From January, 2017 to May, 2019, we collected data from overweight and obese adults (BMI≥23 kg/m2) who registered for a 3-month Gamitaeeumjowi-tang prescription program. Predictive analysis was conducted at the time of three prescriptions, and the expected reduced rate and reduced weight at the next order of prescription were predicted as binary classification (classification benchmark: highest quartile, median, lowest quartile). For the median, further analysis was conducted after using the variable selection method. The data set for each analysis was 25,988 in the first, 6,304 in the second, and 833 in the third. 5-fold cross validation was used to prevent overfitting. Results: Prediction accuracy was increased from 1^st to 2^nd and 3^rd analysis. After selecting the variables based on the median, artificial neural network showed the highest accuracy in 1^st (54.69%), 2^nd (73.52%), and 3^rd (81.88%) prediction analysis based on reduced rate. The prediction performance was additionally confirmed through AUC, Random Forest showed the highest in 1^st (0.640), 2^nd (0.816), and 3^rd (0.939) prediction analysis based on reduced weight. Conclusions: The prediction of weight loss by applying machine learning showed that the accuracy was improved by using the initial weight loss information. There is a possibility that it can be used to screen patients who need intensive intervention when expected weight loss is low.

• The Journal of the Korea Contents Association
• /
• v.18 no.7
• /
• pp.590-599
• /
• 2018

As a basic information to implement the fire plan that dominates multiple targets effectively under the battle environment with limited resources, such a process is mandatory that gives a priority order to a target with the high level of threat by quantitatively computing the threat level of an individual target through the analysis on the target. However, the study has still remained in the initial level on an evaluation algorithm for the threat level of the ground target. Considering this fact, the present paper proposes the evaluation algorithm for the threat by multiple ground targets. The proposed algorithm has a core point to consider the type of target and protected asset to implement the computation of proximity; set the additional value based on the weights indicating the significance of weapon and protected asset; and compute the threat level of a target that considers the characteristics of the target. The evaluation and verification of performances have been implemented through the simulation and visualization of an algorithm proposed in the present paper. From the performance result, as the proposed algorithm has been able to perform effectively the threat assessment according to the weights indicating the significance of weapons and protected assets under diverse environments where weapons and protected assets are located, high utility and effect are expected when applied to an actual ground weapon system.

• Journal of Astronomy and Space Sciences
• /
• v.22 no.1
• /
• pp.13-20
• /
• 2005

Bound abrasive grinding is used for the initial fabrication phase of the precision aspheric mirrors for both space and ground based astronomical telescopes. We developed a new grinding optimization process that determines the input grinding variables for the target surface roughness, checks the grinding error magnitude in resulting surface roughnesses, and minimizes the required machining time. Using the machining data collected from the previous grinding runs and subsequently fed into the multivariable regression engine, the process has the evolving controllability that suggests the optimum set of grinding variables for each target surface roughness. The process model was then used for ten grinding experiments that resulted in the grinding accuracy of $=-0.906{\pm}3.38(\sigma)\;nm(Ra)$ for the target surface roughnesses of Zerodur substrate ranging from 96.1 nm (Ra) to 65.0 nm (Ra) The results imply that the quantitative process optimization technique developed in this study minimizes the machining time and offers the nanometric surface roughness controllability superior to the traditional, qualitative, craftsman based grinding process for the astronomical optical surfaces.

• Journal of Distribution Research
• /
• v.16 no.3
• /
• pp.33-75
• /
• 2011

The ownership structure of a franchise system is determined by the franchisor's strategic choice. A close look at the extant theories and perspectives in economics and management such as resource scarcity theory, agency theory, transaction cost analysis, and mixed ownership theory reveals that firms choose their ownership structure for the sake of economic efficiency, profit potentials, the chance of survival, and other strategic concerns. The present study, on the basis of strategic choice perspective, reviews the divergent theories of a franchise system's ownership structure and its determinants, thus providing a theoretical framework for comparing the contradictory arguments along the several critical dimensions. We also developed and tested the conflicting hypotheses regarding key determinants of ownership structure including firm's age, size, transaction-specific investments, uncertainty, and risk-sharing propensity. Using a FDD (Franchise Disclosure Document) data set of 543 Korean franchisors, we found that the years in business, the total number of employees, days of training, the inverse of the years of franchising, and the requirement of royalty payment have positive relationships with the proportion of company-owned outlets to total number of outlets. On the other hand, the proportion of company-owned outlets was found to have negative relationships with the total number of outlets and the extent of geographic dispersion of outlets, but to have no significant relationships with the initial investment required and the inverse of contract length. Based on the findings, we provide several theoretical and managerial implications for studying ownership structure of franchise systems.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.17 no.1
• /
• pp.47-54
• /
• 1984

From the four tuna purse seiners operating in the western equatorial Pacific waters 370 tuna schools were sampled on attribute of the school, fishing operation of purse seine sit and catch. The data were tabulated and subjected to the statistical tests of independency on the associated object and availability of the school, and catch per set of purse seine fishery as well. The resultant inferences are as follows. 1. Most frequent attributes of the tuna schools found on the surface are associated with sea birds, bait fishes and the flotsams. 2. In fishing operations of purse seine sets on the flotsam-associated schools, the settings were more frequently performed at dawn than in day-time. In fishing operations on the sea-birds-associated schools, the siftings were more frequent in day-time than at dawn. 3. From the flotsam-associated schools the successful sets were significantly more frequent. 4. In the fishing operations of purse seine sets, some of the flotsam-associated schools were subjected to the supplementary sets in success to the initial sets until the schools were consummated. 5. The fish-attracting effect of the flotsam is correlated with structure of the flotsam, but not with length of the flotsam. The flotsams, which tend to attract large tuna schools are the complicated-structure flotsams, i, e. driftwoods with roots or branches or with both of them, otherwise a bunch of uprooted bamboo shrubs, while a log without roots and branches tend to be an attractant inferior to the flotsam of complicated structure.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.3
• /
• pp.306-311
• /
• 2017

This paper deals with the design optimization of the kinematic characteristics of an automotive suspension system. The kinematic characteristics of the suspension determine the attitude of the wheels, such as the toe and camber, which not only relates to tire wear during driving, but also greatly affects the control of the vehicle and its stability, which corresponds to the motion performance of the vehicle. Therefore, it is very important to determine the characteristics of the suspension mechanism at the initial stage of the design. In this study, a displacement analysis is performed to determine the kinematic properties of the suspension for the McPherson strut suspension. For this purpose, a set of constraint equations for the joints constituting the suspension mechanism was established and a program was developed to solve them. We also used ADS, a design optimization program, to obtain the desired kinematic characteristics of the suspension. As the design variables for optimization, we used the coordinates of the hard points, which are the points of attachment of the suspension to the vehicle body, and are defined as the summation of the toe-in for the up and down movement of the wheel as the objective function. As the constraint functions, the maximum camber angle and minimum roll center height, which are design requirements, are considered. As a result of this study, it was possible to determine the optimal locations of the hard points that satisfy both constraint functions and minimize the change of the toe-in.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.11
• /
• pp.755-760
• /
• 2016

The demand for independent generators using renewable energy has been increasing. Among those independent generators, small wind turbine generators have been actively developed. Permanent magnets are generally used for small wind turbine generators to realize a simple structure and small volume. On the other hand, cogging torque is included due to the structure of the permanent magnet synchronous machine, which can be the source of noise and vibration. The cogging torque can be varied by the shape of the permanent magnet and core, and it can be reduced using the appropriate design techniques. This paper proposes a design technique that can reduce the cogging torque by changing the shape of the permanent magnets for SPMSM (Surface Permanent Magnet Synchronous Motor), which is used widely for small wind turbine generators. Evolution Strategy, which is one of non-deterministic optimization techniques, was adopted to find the optimal shape of the permanent magnets that can reduce the cogging torque. The angle and outer diameter of permanent magnet were set as the design variable. A 300W class wind turbine generator, whose pole/slot combination was 8 poles/18 slots, was designed with the proposed design technique. The properties of the generator, including the cogging torque and output voltage, were calculated. The calculation results showed that the cogging torque of the optimized model was reduced compared to that of the initial model. The design technique proposed by this paper can be an effective measure to reduce the cogging torque.