• Journal of Applied Reliability
• /
• v.17 no.2
• /
• pp.112-121
• /
• 2017

Purpose: The most previous works on designing accelerated life tests (ALTs) are focused on the application of a single stress. Because of the difficulty to obtain the sufficient information in a reasonable duration using single stress only, there is needed in practice to use multiple-stress ALTs frequently. This paper presents new practical plans with two stresses for Weibull distribution. Methods: The four-level practical plans based on rectangle test region are proposed and compared with the corresponding three-level statistically optimal plans. Sensitivity analyses for assumed design parameters and life-stress relationship are conducted. Results: A procedure to choose practical ALT plans is illustrated with a numerical example and guidelines for planning two-stress ALTs are provided. Conclusion: The proposed two-stress ALT plans on practical constraints to assess a quantile of Weibull lifetime distribution at the use condition are efficient and robust.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.910-915
• /
• 2004

The objective of this study is to investigate the influence of process parameters, such as power of laser, travel speed of laser and material thickness, on the practical cutting region and the kerfwidth for the case of cutting of CSP 1N sheet using high power Nd:YAG laser with continuous wave(CW). In order to find the practical cutting region and the relationship between process parameters on the kerfwidth, several laser cutting experiments are carried out. The effective heat input is introduced to consider the influence of power and travel speed of laser on the kerfwidth together. From the results of experiments, the allowable cutting region and the relationship between the effective heat input and kerfwidth for the case of cutting of CSP 1N sheet using high power CW Nd:YAG laser have been obtained to improve the dimensional accuracy of the cut area.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.7 s.172
• /
• pp.19-26
• /
• 2005

The objective of this study is to investigate the influence of process parameters, such as power of laser, cutting speed of laser and material thickness, on the practical cutting region and the kerfwidth fer the case of cutting of CSP IN sheet using high power Nd:YAC laser in continuous wave(CW) mode. In order to obtain the practical cutting region and the relationship between process parameters on the kerfwidth, several laser cutting experiments are carried out. The effective heat input is introduced to consider the influence of power and cutting speed of laser on the kerfwidth together. From the results of experiments, the allowable cutting region and the relationship between the effective heat input and kerfwidth fur the case of cutting of CSP 1N sheet using high power CW Nd:YAG laser have been obtained to improve the dimensionalaccuracyofthecutarea.

• Journal of IKEEE
• /
• v.23 no.1
• /
• pp.302-305
• /
• 2019

Non-orthogonal multiple access (NOMA) has been considered for the fifth generation (5G) mobile networks to provide high system capacity and low latency. We calculate the channel capacity for the weak channel user in NOMA and the channel capacity region for NOMA. In this paper, Gaussian mixture channel is compared to the additive white Gaussian noise (AWGN) channel. Gaussian mixture channel is modeled when we assume the practical signal modulation for the inter user interference, such as the binary phase shift keying (BPSK) modulation. It is shown that the channel capacity with BPSK inter user interference is better than that with Gaussian inter user interference. We also show that the channel capacity region with BPSK inter user interference is larger than that with Gaussian inter user interference. As a result, NOMA could perform better in the practical environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.6
• /
• pp.155-164
• /
• 2012

The compression of software development schedule has a limit without regarding to a development manpower. However, the actually developed softwares includes the impossible short time or unreal long time date. Previously suggested models are driving the development schedule from all of the actually developed software without considering these constraints. This paper recommends a standard of minimum and the most suitable development time period. This paper has chosen a criterion that shows the best development schedule among 5 criteria based on the actually performed projects. Moreover, this paper suggests a model that estimates the development schedule based on the best criterion.

• Journal of Digital Convergence
• /
• v.15 no.12
• /
• pp.13-23
• /
• 2017

Obviously, "informatization" is one of the most effective means for improving national competitiveness. In particular, South Korea is a representative successful case implementing informatization in the world. On the contrary, North Kora does not because of serious information devide matter. Given the assumption that information devide is caused by three aspects: the access to information devices or database(information accessibility); the ability to utilize information resources(information mobilization); and the ability to differentiate the quality of information(information consciousness). Based upon three aspects of information devide, we design practical strategies to implement informatization for North Korea region. The purpose of this study is to investigate how to successfully build in informatization of North Korea region for unification era. Drawing on the analysis of successful cases of South Korea, we suggest the valuable guidelines and directions toward success of building informatization of North Korea region. Therefore, this study provides government with specific and practical success strategies for unification era.

• The Korean Journal of Community Living Science
• /
• v.16 no.3
• /
• pp.57-64
• /
• 2005

The purpose of this study was to compare clothing attitudes and the criteria for clothing selection between Korean and Korean-Chinese college female students in the Yanbian region of China. The subjects were selected as follows: 404 Korean female college students in the Choongchung area and 242 Korean-Chinese female college students in the Yanbian region of China. Questionnaires were used to collect the data and the data was analyzed by frequency, factor analysis, and t-test. The major results of this study were as follows: The clothing attitudes of the total respondents were classified into 5 factors: the fashion involving factor, the modesty involving factor, the economy conscious factor, the brand-name oriented factor, and the practical user factor. The modesty involving factor, the economy conscious factor, the brand-name oriented factor, and the practical user factor were significantly different between Korean and Korean-Chinese college female students. Korean consumers thought highly of the economy conscious factor and the practical user factor compared with Korean-Chinese college female students. However, Korean-Chinese college female students thought highly of the brand-name oriented factor and the modesty factor compared with Korean consumers.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.12
• /
• pp.2009-2018
• /
• 2001

This paper presents a region offsetting algorithm for tool-path generation. The proposed region offsetting algorithm is developed by expanding the 'PWID offset algorithm [Choi and Park, 1999]'designed to offset a simple polygon. The PWID offset algorithm has three important steps; 1) remove 'local invalid ranges'by invoking a PWID test, 2) construct a raw offset owe and 3) remove 'global invalid ranges'by finding self-intersections of the raw offset cure. To develop a region offsetting algorithm, we modified the PWID offset algorithm by expanding the concept of the 'global invalid range'in the third step. The time complexity of the proposed algorithm is approximately Ο(n), where n is the number of points, and it is free of numerical errors for practical purposes. The proposed algorithm has been implemented and tested with various real regions obtained by intersecting a sculptured surface with a plane.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.9A
• /
• pp.2333-2344
• /
• 1998

We present a two step approach for estimating the motionand sturcture parameters from region orrespondences in two frames. Given four or more region corresondences on the same planar surface, the motion and planar orientation parameters are first linearly estimated based on second-order approximation of the displacement field of the image plane. Then, using this linear estimate as an initial guess, a nonlinear estimate is obtained by iteratively minimizing an objective function using the exact experession of the displacement field. The objective function involves the centroids of corresponding regions and relationships among low-order moments. Through simulations, we show that the two-step region-based approach gives robust estimates. The performance of nonlinear region-based estimation is compared with that of linear region-based and point-based methods. Experimental results for two image pairs, on esynthetic and one real, ar epresented to show the practical applicability of our approach.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.27 no.5
• /
• pp.57-65
• /
• 2000

Vernacular embodies a culture and economy that are unique to one particular region at a given period, expressed in the lifestyles of the ordinary people of the region. This study aims at interpreting Korean Vernacular Landscape by applying the analytical tool thus developed to the lifestyles of ordinary people found in their permanent dwellings (e. g., villages). By so doing, this study hopes to contribute to building a framework with which to understand the tradition of ordinary people by exploring the uniqueness and basic characteristics of Korean Vernacular Landscape. This study relies primarily on filed studies on, and publications relating to, the agrarian and residential landscapes. The Korean vernacular landscape has not only crude and simple generality, but also individuality derived from cultural circumstances and natural feature. Korean Vernacular Landscape may be characterized as the practical Vernacular Landscape, consisting of the raw materials that were only available in a particular region, shaped by the terrain, and maintained by the customs that varied from a region to a region.