• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.11
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• pp.1683-1695
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• 2009

This study analyzes the production process of eight domestic companies that manufacture scuba diving suits for men with an emphasis on the level of consumer satisfaction in scuba diving suits purchases. One hundred fifty questionnaires were distributed and a total of 140 usable data were coded for further statistical analysis that includes descriptive statistics (frequency and ${\chi}^2$ test) through SPSSWIN 17.0. The results show that a majority of the domestic scuba diving suit companies were either small, manufactured products under original equipment manufacturer (OEM) brands, or were involved in the import business. Many of these companies have developed a local sizing system derived from a company database of customer sizing. As a result, different companies have different sizes that lead to confusion and complication among consumers in selecting the correct size for scuba diving suits. The results indicate that most high-priced diving suits are made of imported fabrics because they had superior quality, fitness, and thickness compared to domestic brands. The degree of consumer satisfaction with scuba diving suits was found to be low in comfort, stuffiness, and activity. Respondents indicated that they felt a little tightness in circumstances such as bust, wrist, and thigh in measurements of circumstances. On the other hand, the respondents showed a high degree of satisfaction with body fitness in scuba diving suits. Further research will clarify a standardized sizing system and develop patterns suitable for Korean men's scuba diving suit body sizes.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.216-227
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• 2005

The head penetrations for control rod drive mechanism and instrumentation systems are installed at the reactor pressure vessel head of PWRs. Primary coolant water and the operating conditions of PWR plants can cause cracking of these nickel-based alloy through a process called primary water stress corrosion cracking (PWSCC). Inspection of the head penetrations to ensure the integrity of the head penetrations has been interested since reactor coolant leakages were found at U. S. reactors in 2000 and 2001. The complex geometry of the head penetrations and the very low echo amplitude from the fine, multiple flaws due to the nature of the see made it difficult to detect and size the flaws using conventional pulse-echo UT methods. Time-of-flight-diffraction technique, which utilizes the time difference between the flaw tips while pulse-echo does the flaw response amplitude from the flaw, has been selected for this inspection for it's best performance of the detection and sizing of the head penetration see flaws. This study defines the limits of the detectable and accurately sizable minimum flaw size which can be detected by the General TOFD and the Delta TOFD techniques for circumferentially and axially oriented flaws respectively. These results assures the reliability of the inspection techniques to detect and accurately size for various kind of flaws, and will also be utilized for the future development and qualifications of the TOFD techniques to enhance the detecting sensitivity and sizing accuracy of the flaws of the reactor head penetrations in nuclear power plants.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.351-358
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• 2013

In the electric power supplying industry, outdoor sealing end (pothead) is used and sometimes it is necessary to check the seismic qualification analysis or test which is intended to demonstrate that the equipment have adequate integrity to withstand stress of the specified seismic event and still performs their function. And since the pothead is mounted on the supporting jig, the avoidance of resonance between the pothead and jig is required. In order to design jig, three types of optimization are performed to get the minimum weight while satisfying the natural frequency constraint using ANSYS. Optimal array, position and thickness of truss members of the jig are obtained through topology, shape and sizing optimization process, respectively. And seismic analysis of the pothead on the jig for given RRS acceleration computes the displacement and stress of the pothead which shows the safety of the pothead. The obtained natural frequency, mass, and member thickness of the jig are compared with those of the reference jig which was used for seismic experimental test. The numerical results of the jig in the research is more optimized than the jig used in the experimental test.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.457-458
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• 2008

We have developed new process to product Al clad steel wire. New machine was modified to be able to apply an four step of "foiling-sizing-cladding-drawing" considering low clad temperature and high clad pressure. The foiling part for continuous foiling of Al sheet was designed and machine. Cladding properties at Al and steel interface were investigated for the processes of new work.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.27-37
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• 2020

Structural optimization problems with discrete design variables require more function calculations (or finite element analyses) than those in the continuous design space. In this study, a method to find an optimal solution in the discrete design of the truss structure is presented, reducing the number of function calculations. Because a continuous optimal solution is the Karush-Kuhn-Tucker point that satisfies the optimality condition, it is assumed that the discrete optimal solution is around the continuous optimum. Then, response values such as weight, displacement, and stress are predicted using approximate models-referred to as hybrid metamodels-within specified design ranges. The discrete design method using the hybrid metamodels is used as a post-process of the continuous optimization process. Standard truss design problems of 10-bar, 25-bar, 15-bar, and 52-bar are solved to show the usefulness of this method. The results are compared with those of existing methods.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.441-444
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• 2009

In this research, a hot and cold combined forging process for manufacturing net-shape one-way clutch bearing outer race of an automobile automatic transmission unit is developed. The process is composed of hot forging for manufacturing an optimized gear-like perform and precision cold forging for sizing the perform into final net-shape product. Finite element simulation techniques are applied to find the optimized process designs including blank and die shapes. The predictions and experiments are compared, revealing that they are in good agreement with each other. The dimensional test showed that the important dimensional requirements on gear tooth-like shape of the forged product were fulfilled.

• Transactions of Materials Processing
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• v.3 no.3
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• pp.282-290
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• 1994

The outer race of BJ type C.V.Joint has a complicated shape and ball grooves. It is produced by cold or warm precision forging. Especially, the precision level of the ball grooves determines the quality of the part. The objective of the present study is to develop process conditions of the cold forging using the plasticine. Because the cold forging consists of forward extrusion, upsetting, backward extrusion and cold sizing, the study was focused on finding the best perform for each process. The data obtained from the study will be used in the design of the cold forging process for the outer race.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.4
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• pp.63-71
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• 2010

Modular design is a very important design methodology that allows designers to develop a product family at low product development and production cost. This design methodology is also very powerful for products that require frequent design changes due to customer requirements. Most research on modular design is focused on the modularization based on functional decomposition, physical interface and manufacturing process of parts. In this paper, we propose a modularization method that takes size of human body parts into consideration for products which have physical interactions with the products such as office chairs and sport machines. Evaluation of modular design is based on dependence measurement between every pair of components in the design. In addition we proposed a module sizing method for the maximization of customer satisfaction in MC(Mass Customization) environment.

• Journal of Aerospace System Engineering
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• v.7 no.3
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• pp.15-19
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• 2013

Tail wing is important to designing of civil aircrafts, because it is responsible for aircraft stability and control. Tail wing has a role in aircraft control and makes aircraft fly stably without any pilot control input. Also, designing of tail wing determine trim drag force in whole aircraft. Center of gravity(CG) of aircraft travels with various effects as placement of passenger's seats, location of cargo bay, etc. In designing horizontal tail volume, aircraft CG travel has to be considered to have margin so that it should be sized to provide adequate stability and control for the airplane's entire CG range throughout the flight envelope. Finally, it is essential to have sufficient elevator control to perform stall at forward CG for all flaps down configurations. Such stalls establish the FAR stall speed which airplane take-off and landing performance. This paper deals with the process for tail wing design regarding the aircraft CG travel and results for 95-seat type turboprop aircraft.

• KIEAE Journal
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• v.14 no.6
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• pp.105-110
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• 2014

The basic factors determining the amount of energy used in hospital buildings are weather conditions and building factors. But the real energy consumer is central plant equipment such as boilers and chillers that produce thermal energy for heating and cooling. Inaccurate decision of the primary equipment's size can cause a high initial-cost, an excessive equipment space, a wasted energy by low operation-efficiency and shortening of the machine's life. In this reason, the decision of optimal size for central plant equipment is very important. There are several factors for the decision such as an operation factor, a factor (equipment factor), piping losses and a simultaneous usage factor applied in the sizing process except a basic cooling load. But there is no standard method for applying those factors. Usually, factors are applied individually by an experience or custom of each engineer. In this study, the authors emphasize the meaning and the problem of those factors, examine them by analyzing factors which were applied to actual practices, and propose the recommendation value of safety, load, operation factors and application methods.