• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.4
• /
• pp.199-206
• /
• 1997

The inner pulley is an automobile component used as air conditioner clutch assembly. In cold forging of inner pulley, the design requirements are to keep the same height of the inner rib and outer one, and to make uniform the hardness distribution in the forged product. In industry, the design of forging processes is performed based on experience-oriented technology, that is, designers experience and expensive trial and error. Using the rigid-plastic finite element simulations. we design the optimal process conditions, which has a preforming operation. Also the final product configuration of forging has to be designed again in view of metal flow involved in the operation, derived from the finite element simulations. The forged pulley is investigated by checking the hardness distribution and it is noted that distribution has improved to be even and high enough for industrial application.

• Korean Management Science Review
• /
• v.29 no.1
• /
• pp.1-14
• /
• 2012

The goal of the multi-reservoir operation planning is to provide an optimal release plan that maximize the reservoir storage and hydropower generation while minimizing the spillages. However, the reservoir operation is difficult due to the uncertainty associated with inflows. In order to consider the uncertain inflows in the reservoir operating problem, we present a Stochastic Dynamic Programming (SDP) model based on the markov decision process (MDP). The objective of the model is to maximize the expected value of the system performance that is the weighted sum of all expected objective values. With the SDP model, multi-reservoir operating rule can be derived, and it also generates the steady state probabilities of reservoir storage and inflow as output. We applied the model to the Geum-river basin in Korea and could generate a multi-reservoir monthly operating plan that can consider the uncertainty of inflow.

• Proceedings of the KIEE Conference
• /
• 1987.11a
• /
• pp.106-108
• /
• 1987

Until now, inflow has been handled an independent log-normal random variable in the problem of planning the long-term operation of a multi-reservoir hydrothermal electric power generation system. This paper introduces the detail study for making rule curve by applying weekly time interval for handling inflows. The hydro system model consists of a set of reservoirs and ponds. Thermal units are modeld by one equivalent thermal unit. Objective is minimizing the total cost that the summation of the fuel cost of equivalent thermal unit at each time interval. For optimization, stochastic dynamic programming(SDP) algorithm using successive approximations is used.

• Proceedings of the KIEE Conference
• /
• 1993.07a
• /
• pp.195-197
• /
• 1993

This raper describes a nev program designed as a part of the integrated software package for distribution system planning and operation. The program accesses electrical map databases which include both electrical and geographical information. Data retrieval, load flow analyses, and reconfiguration studies can be easily performed in highly interactive environment on graphics and pull down menus, case study results demonstrate the practical usefulness of the program at the real systems.

• International Journal of Aeronautical and Space Sciences
• /
• v.17 no.1
• /
• pp.89-100
• /
• 2016

Given the unpredictability of the space environment, satellite communications are manually performed by exchanging telecommands and telemetry. Ground support for orbiting satellites is given only during limited periods of ground antenna visibility, which can result in conflicts when multiple satellites are present. This problem can be regarded as a scheduling problem of allocating antenna support (task) to limited visibility (resource). To mitigate unforeseen errors and costs associated with manual scheduling and mission planning, we propose a novel method based on a genetic algorithm to solve the ground support problem of multiple satellites and antennae with visibility conflicts. Numerous scheduling parameters, including user priority, emergency, profit, contact interval, support time, remaining resource, are considered to provide maximum benefit to users and real applications. The modeling and formulae are developed in accordance with the characteristics of satellite communication. To validate the proposed algorithm, 20 satellites and 3 ground antennae in the Korean peninsula are assumed and modeled using the satellite tool kit (STK). The proposed algorithm is applied to two operation modes: (i) telemetry, tracking, and command and (ii) payload. The results of the present study show near-optimal scheduling in both operation modes and demonstrate the applicability of the proposed algorithm to actual mission control systems.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1816-1819
• /
• 2003

As a result of milling operation, we expect to have burr at the outward edge of workpiece. Also, it causes undesirable problems such as deburring cost, low quality of machined surface, and bottleneck in manufacturing process. Though it is impossible to totally remove burr in machining, it is necessary to plan a machining process that minimizes the occurrence of burr. In this paper, a scheme is proposed which identifies the tool path of the milling operation with minimum burr. In the previous research, a Burr Expert System was developed where the feature identification, the cutting condition identification, and the analysis on exit burr formation are the key steps in the program. The Burr Expert System predicts which portion of workpiece would have the exit burr in advance so that we can calculate the burr length of each milling operation. Here, the critical angle determines whether the burr analyzed is an exit burr or not. So the burr minimization scheme becomes to minimize the burr with critical angle. By iterating all the possible tool paths in certain milling operation, we can identify the tool path with minimum burr.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.430-431
• /
• 2011

Recently the power system consists of the more complicated structure, due to increase of power demands. In this circumstance, the congestion and loss capacity in transmission line is also increased. Accordingly, the investment planning of transmission system is required to reduce the congestion and loss of the transmission line. In study of the planning of domestic and international transmission expansion, the reliability of transmission planning and minimizing Investment cost is focused. However, the study has not been performed systematically in economic aspects. Typically, the congestion and loss costs have been individually calculated. It is not consider the mutual relationship between the congestion cost and the loss cost. This paper proposes a method to compute concurrently the congestion and loss costs. This purpose is to calculate the more exact value for economic assessment of the power system operation.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.8
• /
• pp.807-813
• /
• 2011

High precision of planning in the preoperative phase can contribute to increase operational safety during computer-aided spinal fusion surgery, which requires extreme caution on the part of the surgeon, due to the complexity and delicacy of the procedure. In this paper, an advanced preoperative planning framework for spinal fusion is presented. The framework is based on spinal pedicle data obtained from CT (Computed Tomography) images, and provides optimal insertion trajectories and pedicle screw sizes. The proposed approach begins with safety margin estimation for each potential insertion trajectory that passes through the pedicle volume, followed by procedures to collect a set of insertion trajectories that satisfy operation safety objectives. The radius of a pedicle screw was chosen as 70% of the pedicle radius. This framework has been tested on 68 spinal pedicles of 8 patients requiring spinal fusion. It was successfully applied, resulting in an average success rate of 100% and a final safety margin of $2.44{\pm}0.51mm$.

• Management Science and Financial Engineering
• /
• v.17 no.1
• /
• pp.45-63
• /
• 2011

The aim of this paper is to consider the process of supplying trained workers with knowledge and skills for upcoming business opportunities and the process of training apprentices to be prepared to meet future demands in an IT service firm. As the demand for new workers fluctuates, a firm should employ a buffer workforce such as apprentices or interns. However, as a result of rapid business development, the capacity of the buffer may be exceeded, thus requiring the company to recruit skilled workers from outside the firm. Therefore, it is important for a firm to map out a strategy for manpower planning so as to fulfill the demands of new business and minimize the operation costs related to training apprentices and recruiting experienced workers. First, this paper analyzes the supply and demand of workers for the IT service in a knowledge-intensive field. It then presents optimal human resource planning strategies via the familiar method of stochastic process. Also, we illustrate that our model is applied to the human resource planning of an information security service firm in South Korea.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.23 no.3
• /
• pp.81-90
• /
• 2017

Purpose: The regional trauma center should be a trauma treatment center equipped with facilities, equipment, and manpower capable of providing optimal treatment such as emergency surgery to a severely traumatized patient upon arrival at the hospital. In order to establish a medical system for effective severe diseases, it is necessary to prepare architectural planning guidelines for the regional trauma centers. Methods:: Analyze the spatial configuration, and the area composition of the regional trauma center, And to provide basic data for building a more efficient regional trauma center. The spatial composition analysis divides the space into initial care, resuscitation, patient area, nursing area, diagnostic test, staff training, staff support, public, and analyzes the area and interconnection of each space. Results: The area that must be included in the regional trauma center is the resuscitation area, the patient area, the diagnostic examination area, architectural planning should be designed to enhance the interconnection of the areas. IIn addition, a regional trauma center should be planned as a separate from the existing facility so that it can be installed and operated independently. Implications: A regional trauma center should be built as a stand alone operation and the space should be planned as a more efficient route.