• Journal of Korean Institute of Industrial Engineers
• /
• v.25 no.1
• /
• pp.35-46
• /
• 1999

The introduction of general purpose machining centers and the information system based on computer network has added a new control problem to the classical job shop control problems: a routing problem. A routing problem is to determine the machine on which a part will be processed. The modern manufacturing systems are given much system status information including the arrival time of the future parts via the computer network for automation. This paper presents and tests the performance of a routing procedure, LARP(Look-Ahead Routing Procedure) which uses look-ahead information on the future arrival of parts in the system. The manufacturing system considered in this paper has multi-stations which consists of general purpose machines and processes parts of different types. The application of LARP under many operating conditions shows that the reduction of part flow time and tardiness from the cases without using this information is up to 8% for flow time and 21% for tardiness. The procedure introduced here can be used for many highly automated systems such as an FMS and a semi-conductor fabrication system for routing where the arrivals of parts in the near future are known.

• Korean Institute of Interior Design Journal
• /
• v.27 no.1
• /
• pp.132-139
• /
• 2018

The high-rise and high-density apartment complexes are built on a large scale and occupy a large portion of the city. The facade of the apartment has a great influence on the cityscape. In particular, the lower part of apartment design gives people to important impressions. For the harmonious landscape of the city, the color plan emphasizes its importance as an influential visual design element that forms the urban landscape. In specialized apartment design, especially finishing material on lower-parts of apartment which is recognized by pedestrian is more important planning factor. Also, finishing material which is one of the primary design elements is important for making the entire image about the building with color. Nowadays stone is mostly used for specialized design on lower-level in apartments. Stone makes luxurious image and harmonious landscape as a nature material. But when planning for design, only general stone graphic or pictures is used without specific plan, after construction, there is a big difference between a plan and the actual color and image. Thus based on exact understanding of stone, I analyzed current state of expression for stone which is used for lower-parts of apartments in Daegu. By this, the purpose of this study is to present detailed data to offer the basis for planning specialized design of lower-parts of apartment.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1996.04a
• /
• pp.121-124
• /
• 1996

In general, cellular manufacturing system can be constructed by the following two steps. The first step forms machine cells and part families, and the second step determines cell layout based on the result of first step. Cell layout has to be considered when cell is formed becauese the result of cell formation affects it. This paper presents a cell formation algorithm and proposes an integrated mathematical model for cell formation and cell layout. The cell formation algorithm minimizes the number of exceptional element in cellular manufacturing system. New concept for similarity and incapability is introduced, based on machine-operation incidence matrix and part-operation incidence matrix. One is similarity between the machines, the other is similarity between preliminary machine cells and machines. The incapability identifies relations between machine cells and parts. In this procedure, only parts without an exceptional element are assigned to machine cell. Bottleneck parts are considered with cell layout design in an integrated mathematical model. The integrated mathematical model determines cell layout and assigns bottleneck parts to minimize the number of exceptional element and intercell moving distance, based on linearixed 0-1 integer programming. The proposed algorithm is illustrated by using numerical examples.

• Journal of Aerospace System Engineering
• /
• v.10 no.2
• /
• pp.1-6
• /
• 2016

The thermal analysis of electronic equipment is required to predict the reliability of electronic equipment being loaded on a satellite. The transient heat transfer of electronic equipment that was developed recently has been generated using a large-scale integration circuit. If there is a transient heat transfer between EEE(Electric, Electronic and Electro mechanical) parts, it may lead to failure the satellite mission. In this study, we performed the thermal design and analysis for reliability of APD(Antenna Pointing Driver) electronics for activation of a spaceborne X-band 2-axis antenna. The EEE parts were designed using a thermal mathematical model without the thermal mitigation element. In addition, thermal analysis was performed based on the worst case for verifying the reliability of EEE parts. For the thermal analysis results, the thermal stability of electronic equipment has been demonstrated by satisfying the de-rating junction temperature.

• International Journal of Precision Engineering and Manufacturing
• /
• v.8 no.3
• /
• pp.14-19
• /
• 2007

Rapid prototyping (RP) technology can fabricate any 3D physical model regardless of geometric complexity using the layered manufacturing (LM) process. Stereolithography (SL) is the best-known example of RP technology. In general, the surface quality of a raw SL-generated part is unsatisfactory for industrial purposes due to the step artefact created by the LM process. Despite of the increased number of applications for SL parts, this side effect limits their uses. In order to improve their surface quality, additional post-machining finishing, such as traditional grinding, is required, but post-machining is time consuming and can reduce the geometric accuracy of a part. Therefore, this study proposes a post-machining technology combining coating and grinding processes to improve the surface quality of SL parts. Paraffin wax and pulp are used as the coating and grinding materials. By grinding the coating wax only up to the boundary of the part, the surface smoothness can be improved without damaging the surface. Finally, moulding and casting experiments were performed to confirm the suitability of the SL parts finished using the proposed process with rapid tooling (RT) techniques.

• Composites Research
• /
• v.32 no.2
• /
• pp.102-107
• /
• 2019

Several studies related to reinforce composites structures in the through thickness direction have been developed along the years. As follows, in this study a new reinforced process is proposed based on previous experimental results using a novel stitching process in T-joints and one-stitched specimens. It was established the need to perform more analysis under standard test methods to obtain a better understanding. FEM analysis were compared after performed mode I interlaminar fracture toughness test, using different stitching patterns to analyze the through thickness strength with reference laminates without stitching. The stitching patterns were defined in $2{\times}2$ and $3{\times}3$, where the upper and lower head of the non-continuous stitching process (I-Fiber) has proven to influence in a higher through thickness strength of the laminate. In order to design the numerical model, cohesive parameters were required to define the surface to surface bonding elements using the cohesive zone method (CZM) and simulate the crack opening behavior from the double cantilever beam (DCB) test.

• Korean Journal of Poultry Science
• /
• v.21 no.4
• /
• pp.277-284
• /
• 1994

The functional properties of mechanically deboned chicken meat(MDCM) from whole carcass, whole carcass without exsanguination, neck without skin, leg hone, and upper back and rib were studied. Also, the effects of adding different levels of gelatin and MDCM to the comminuted meats were investigated. Proximate composition values of MDCM ranged from 54.2 to 68.6% moisture, 14.5 to 19.7% protein, 12.3 to 30.1% fat, and 1.1 to 1.3% ash. The MDCM from leg hone had a higher content of fat, and a lower contents of moisture and protein. The MDCM from neck without skin tended to be opposite to the MDCM from leg hone. The total pigment and myoglobin levels were highest in MDCM from whole carcass without exsanguination such as 3.83 and 0.29 rng /g, and those from the other parts were 1.58~2.93 mg /g and 0. 17~0.31 mg /g, respectively. The emulsifying capacity and water holding capacity were highest in MDCM from neck without skin which contained lower levels of fat, collagen and hydroxyproline, but a higher level of salt soluble protein. The emulsifying capacity of comminuted meat decreased as gelatin content increased. The extractability of hydroxyproline from gelatin showed a higher solubility in acidic solution. The MDCM could he added up to 20% level without detrimentally affecting functional properties of comminuted meats although they had less water holding capacity and cooking loss as the proportion of MDCM increased.

• Journal of the Korean earth science society
• /
• v.37 no.5
• /
• pp.277-285
• /
• 2016

We introduce a depth scaling strategy to improve the accuracy of frequency-domain elastic full waveform inversion (FWI) using the new pseudo-Hessian matrix for seismic data without low-frequency components. The depth scaling strategy is based on the fact that the damping factor in the Levenberg-Marquardt method controls the energy concentration in the gradient. In other words, a large damping factor makes the Levenberg-Marquardt method similar to the steepest-descent method, by which shallow structures are mainly recovered. With a small damping factor, the Levenberg-Marquardt method becomes similar to the Gauss-Newton methods by which we can resolve deep structures as well as shallow structures. In our depth scaling strategy, a large damping factor is used in the early stage and then decreases automatically with the trend of error as the iteration goes on. With the depth scaling strategy, we can gradually move the parameter-searching region from shallow to deep parts. This flexible damping factor plays a role in retarding the model parameter update for shallow parts and mainly inverting deeper parts in the later stage of inversion. By doing so, we can improve deep parts in inversion results. The depth scaling strategy is applied to synthetic data without lowfrequency components for a modified version of the SEG/EAGE overthrust model. Numerical examples show that the flexible damping factor yields better results than the constant damping factor when reliable low-frequency components are missing.

• Journal of computational fluids engineering
• /
• v.20 no.3
• /
• pp.8-14
• /
• 2015

More and more, spaces are decreasing which satisfy multiple requirements for wind power plants. However, areas which have excellent wind resources and are free to civil complaints occupy a large space, although they are exposed to the cryogenic environment. This study conducted a thermal-fluid analysis of a cryogenic chamber for testing large wind turbine parts exposed to the cryogenic environment. The position of supply air is placed to the upper area to compare each cooling performance for each location of various outlets in mixing ventilated conditions. The study carried out CFD analysis for the chamber both with and without a test object. For the cases without the test object, the air temperature of the upper supply and down extract type chamber was cooled faster by 5-100% than the others. However, for the cases with the test object, the object temperature of upper supply and center extract on the opposite side type chamber was cooled faster by 33-132% than the others. The cooling performance by the air inside the chamber and the test object did not show the same pattern, which implicates the need to consider the cooling performance by not only the air but also the test object in the large cryogenic chamber design for testing large parts.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.4
• /
• pp.7-21
• /
• 2000

This paper describes an overview of the thixoforming and thixomolding processes. Semi-solid metalworking (SSM), which is called the thixoforming process of aluminium materials, incorporates the elements of both casting and for the manufacture of near net shape parts. The SSM has some advantages such as net shape or near net shape manufacturing, the ability to form thin walls, excellent surface finish, tight tolerance, and excellent dimensional precision. The thixomolding process of Mg alloy (AZ9l) is a combination of two technologies both conventional die casting and plastic injection molding. The feed material used is a machined chip with a geometry of approximately 1 mm square and a length of 2~3 mm. The semi-solid forming (SSF) of high quality aluminium and magnesium parts will be established in the automotive and electronic industry, in the future. The hybrid method of casting/forging has been caused attention. This process uses a preformed material made by casting instead of the wrought material and finishes it by a single forging process. This process is expected to lower costs without sacrificing the mechanical and finishes it by a single forging process. The process is expected to lower costs without sacrificing the mechanical properties. The authors, intending that the casting/forging process contributes to a reduction in production cost of aluminum automotive parts in Korea, describes the feature of the casting/forging process, aluminum alloys suitable for the cast preform, microstructure and mechanical properties of the cast preform, application examples of cast/forging, and further study.