• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.40 no.1
• /
• pp.35-40
• /
• 2017

A most important progress in civilization was the introduction of mass production. One of main methods for mass production is die-casting molds. Due to the high velocity of the liquid metal, aluminum die-casting is so complex where flow momentum is critical matter in the mold filling process. Actually in complex parts, it is almost impossible to calculate the exact mold filling performance with using experimental knowledge. To manufacture the lightweight automobile bodies, aluminum die-castings play a definitive role in the automotive part industry. Due to this condition in the design procedure, the simulation is becoming more important. Simulation can make a casting system optimal and also elevate the casting quality with less experiment. The most advantage of using simulation programs is the time and cost saving of the casting layout design. For a die casting mold, generally, the casting layout design should be considered based on the relation among injection system, casting condition, gate system, and cooling system. Also, the extent or the location of product defects was differentiated according to the various relations of the above conditions. In this research, in order to optimize the casting layout design of an automotive Oil Pan_BR2E, Computer Aided Engineering (CAE) simulation was performed with three layout designs by using the simulation software (AnyCasting). The simulation results were analyzed and compared carefully in order to apply them into the production die-casting mold. During the filling process with three models, internal porosities caused by air entrapments were predicted and also compared with the modification of the gate system and overflows. With the solidification analysis, internal porosities occurring during the solidification process were predicted and also compared with the modified gate system.

• The Journal of Engineering Research
• /
• v.6 no.1
• /
• pp.5-14
• /
• 2004

Finding a solution to a constraint satisfaction problem requires choosing values for variables so as to satisfy the constraints of the problem. A constraint is simply a logical relation among several unknowns (or variables), each taking a value in a given domain. Conventional constraint-based scheduling systems are not enough to satisfy the all constraints because there are conflicts between them. In this paper, we propose a method for interactive scheduling, which have two major problems: first, it is hard to satisfy concretely all various kinds of constraints, and second, the search space is extremely large and requires a long execution time. To solve the above problems, we introduce the Interactive Scheduling System (ISS) that interacts with the user to exchange suggestions each other. Our system is performed in two steps: knowledge base generation of an initial assignment and iterative improvement with the user(host or internet client) to satisfy the constraints. Applying our system, we actually constructed timetables for our university, where the scheduling time is considerably reduced.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.1476-1479
• /
• 1996

The ring rolling process is one of the best known ring production method. The present model based control system was designed for rings with rectangle cross-section yet. An Adaptive Fuzzy Control for Closed-Die Ring-Rolling was developed in order to enhance the flexibility of the radial-axial ring rolling machine and to produce the rings with highly complex cross-section profile, roller bearing rings. A fuzzy method was implemented because of its simple application and to utilize the known process knowledge. The quality of the control system was estimated by die filling grad, which is strong dependent on the rising time of the controller. The rolling process parameters were also varied to determine their influence on filling of the ring profile. Die filling met the requirement of the industry.

• Journal of Korean Critical Care Nursing
• /
• v.13 no.1
• /
• pp.27-43
• /
• 2020

Purpose : This integrative review aimed to synthesize studies on intensive care unit (ICU) nurses' attitude, perceptions, and experiences toward end-of-life care decision-making. Methods : Using Whittermore and Knafl (2005)'s methods, we identified and synthesized research articles published in domestic journals between the years 2003 and 2019 and evaluated the quality of selected articles using the Mixed Methods Appraisal Tool. Results : In the 13 studies reviewed, 12 were published prior to enactment of the "The Act for Hospice and Palliative Care and Decision-Making about Life-Sustaining Treatment (2018)." All nine quantitative studies identified were based on cross-sectional descriptive survey. In four qualitative studies, content analysis (n=2) and phenomenology (n=2) were used. Overall, ICU nurses were well-aware of the necessity of communicating and limiting life-sustaining treatments. Many ICU nurses had positive attitude towards limiting life-sustaining treatments to promote patients' comfort and dignity. Although nurses were willing to take active roles, they also reported having experienced high stress in the process of decision-making and implementation. Conclusions : It is important to prepare ICU nurses with proper knowledge and attitude regarding the topic area. It is also equally important to develop systems to support nurses' emotional stress and moral distress during communication, decision-making, and implementation.

• Fashion & Textile Research Journal
• /
• v.12 no.2
• /
• pp.162-171
• /
• 2010

This study aims to discuss what changes Korean clothing companies and manufacturers have undergone with production facilities moving abroad due to offshore outsourcing and examine what conditions the clothing manufacturers are facing and how the clothing companies recognize those manufacturers. For these purposes, in-depth interviews were conducted with 24 firms with annual production capacity of more than 200,000 pieces among clothing brands for the domestic market, clothing exporters and promotion agencies. Those interviewed firms were the companies who were found to produce more than 200,000 pieces of clothing per year, and the interview-based survey was conducted from December 18, 2008 to January 30, 2009. The key findings from this study are as follows; first, a high percentage of interviewed firms were producing only a small number of items in Korea with a large part of their production line transferred abroad or outsourcing all of their production abroad only with their headquarters in Korea. Second, many were employing contractors rather than their own factories. Third, when asked about the wage levels of clothing manufacturers, many of the clothing companies gave responses such as: 'They are just our contractor, so we respect their decision,' 'We don't know because it's none of our business,' or 'We don't know at all.' Fourth, when asked about the work environment of clothing manufacturers, the clothing companies gave responses such as: 'We know in part,' 'To our knowledge, they conform to the Labor Standards Law,' or 'We don't know at all.' Fifth, the production line of clothing manufacturers featured straight-line systems, specialization, pairing and compounding/mixing. Sixth, it was found that clothing companies had interest in mass customization but their preparations were not satisfactory.

• Journal of Internet Computing and Services
• /
• v.21 no.2
• /
• pp.19-26
• /
• 2020

This paper analyses the feasibility of using implantable antennas to detect and monitor tumors. We analyze this setting according to the wireless propagation loss and signal fading produced by human bodies and their environment in an indoor scenario. The study is based on the ITU-R propagation recommendations and prediction models for the planning of indoor radio communication systems and radio local area networks in the frequency range of 300 MHz to 100 GHz. We conduct primary estimations on 915 MHz and 2.4 GHz operating frequencies. The path loss presented in most short-range wireless implant devices does not take into account the human body as a channel itself, which causes additional losses to wireless designs. In this paper, we examine the propagation through the human body, including losses taken from bones, muscles, fat, and clothes, which results in a more accurate characterization and estimation of the channel. The results obtained from our simulation indicates a variation of the return loss of the spiral antenna when a tumor is located near the implant. This knowledge can be applied in medical detection, and monitoring of early tumors, by analyzing the electromagnetic field behavior of the implant. The tumor was modeled under CST Microwave Studio, using Wisconsin Diagnosis Breast Cancer Dataset. Features like the radius, texture, perimeter, area, and smoothness of the tumor are included along with their label data to determine whether the external shape has malignant or benign physiognomies. An explanation of the feasibility of the system deployment and technical recommendations to avoid interference is also described.

• Advances in aircraft and spacecraft science
• /
• v.2 no.2
• /
• pp.217-232
• /
• 2015

To prevent over-testing of the test-item during random vibration testing Scharton proposed and discussed the force limited random vibration testing (FLVT) in a number of publications. Besides the random vibration specification, the total mass and the turn-over frequency of the load (test item), $C^2$ is a very important parameter for FLVT. A number of computational methods to estimate $C^2$ are described in the literature, i.e., the simple and the complex two degrees of freedom system, STDFS and CTDFS, respectively. The motivation of this work is to evaluate the method for the computation of a realistic value of $C^2$ to perform a representative random vibration test based on force limitation, when the adjacent structure (source) description is more or less unknown. Marchand discussed the formal description of getting $C^2$, using the maximum PSD of the acceleration and maximum PSD of the force, both at the interface between load and source. Stevens presented the coupled systems modal approach (CSMA), where simplified asparagus patch models (parallel-oscillator representation) of load and source are connected, consisting of modal effective masses and the spring stiffness's associated with the natural frequencies. When the random acceleration vibration specification is given the CSMA method is suitable to compute the value of the parameter $C^2$. When no mathematical model of the source can be made available, estimations of the value $C^2$ can be find in literature. In this paper a probabilistic mathematical representation of the unknown source is proposed, such that the asparagus patch model of the source can be approximated. The chosen probabilistic design parameters have a uniform distribution. The computation of the value $C^2$ can be done in conjunction with the CSMA method, knowing the apparent mass of the load and the random acceleration specification at the interface between load and source, respectively. Data of two cases available from literature have been analyzed and discussed to get more knowledge about the applicability of the probabilistic method.

• Proceedings of the Korean Society for Bioinformatics Conference
• /
• 2000.11a
• /
• pp.56-58
• /
• 2000

Post-genomics may be defined in different ways depending on how one views the challenges after the genome. A popular view is to follow the concept of the central dogma in molecular biology, namely from genome to transcriptome to proteome. Projects are going on to analyze gene expression profiles both at the mRNA and protein levels and to catalog protein 3D structure families, which will no doubt help the understanding of information in the genome. However complete, such catalogs of genes, RNAs, and proteins only tell us about the building blocks of life. They do not tell us much about the wiring (interaction) of building blocks, which is essential for uncovering systemic functional behaviors of the cell or the organism. Thus, an alternative view of post-genomics is to go up from the molecular level to the cellular level, and to understand, what I call, the "interactome"or a complete picture of molecular interactions in the cell. KEGG (http://www.genome.ad.jp/kegg/) is our attempt to computerize current knowledge on various cellular processes as a collection of "generalized"protein-protein interaction networks, to develop new graph-based algorithms for predicting such networks from the genome information, and to actually reconstruct the interactomes for all the completely sequenced genomes and some partial genomes. During the reconstruction process, it becomes readily apparent that certain pathways and molecular complexes are present or absent in each organism, indicating modular structures of the interactome. In addition, the reconstruction uncovers missing components in an otherwise complete pathway or complex, which may result from misannotation of the genome or misrepresentation of the KEGG pathway. When combined with additional experimental data on protein-protein interactions, such as by yeast two-hybrid systems, the reconstruction possibly uncovers unknown partners for a particular pathway or complex. Thus, the reconstruction is tightly coupled with the annotation of individual genes, which is maintained in the GENES database in KEGG. We are also trying to expand our literature surrey to include in the GENES database most up-to-date information about gene functions.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.1C
• /
• pp.112-121
• /
• 2002

In this paper, we present a design of a hash processor for data security systems. Two standard hash algorithms, Sha-1(American) and HAS-1600(Korean), are implemented on a single hash engine to support real time processing of the algorithms. The hash processor can also be used as a PRNG(Pseudo-random number generator) by utilizing SHA-1 hash iterations, which is being used in the Intel software library. Because both SHA-1 and HAS-160 have the same step operation, we could reduce hardware complexity by sharing the computation unit. Due to precomputation of message variables and two-stage pipelined structure, the critical path of the processor was shortened and overall performance was increased. We estimate performance of the hash processor about 624 Mbps for SHA-1 and HAS-160, and 195 Mbps for pseudo-random number generation, both at 100 MHz clock, based on Samsung 0.5um CMOS standard cell library. To our knowledge, this gives the best performance for processing the hash algorithms.

• Journal of Elementary Mathematics Education in Korea
• /
• v.2 no.1
• /
• pp.61-80
• /
• 1998

Whereas research on telelearning in educational technology area is lively done, that in mathematics education area is not. Related to the open education, telelearning has 4 models: the distance classroom model, the front-end system design, the knowledge construction model, and the teaching model based on data. S/W, C/W, and H/W are the components of telelearning system. For an effective mathematics telelearning system, H/W and S/W which use multimedia with complex multimode information such as text, graphics, animation, video, and audio are necessary. Examples of telelearning systems on going are MIPOS, SDS telelearning system, telelearning system of the Naechon Elementary School, and Doorae Multimedia Application Development Platform.