• Title/Summary/Keyword: 확률적 상황

Search Result 543, Processing Time 0.028 seconds

Analysis of Correlation between Construction Business and Insolvency of Construction Company (건설경기와 건설업체 부실화 간의 관계성 분석)

  • Seo, Jeong-Bum;Lee, Sang-Hyo;Kim, Jae-Jun
    • Korean Journal of Construction Engineering and Management
    • /
    • v.14 no.3
    • /
    • pp.3-11
    • /
    • 2013
  • The changes in construction business have impact on overall operation of construction companies. Poor business of construction companies following a s low industrial cycle could have broader implications and influences on the industry. Since a construction project involves various stakeholders including public organizations, financial institutions and households, a downturn in construction industry might lead to significant economic loss. In this regard, it is meaningful to examine the relationship between changes in construction business cycles and insolvency of construction companies. This study conducts an empirical analysis of the relationship between construction business cycles and how much they affect operation of construction companies. To this end, KMV model was used to estimate probability of bankruptcy, which represents business condition of a construction company. To examine construction business cycles, investment amount for different construction types-residential, non-residential, and construction work-was used as a variable. Based on the investment amount, VECM was applied and the analysis results suggested that construction companies should put priority on diversifying project portfolio. In addition, it was shown that once a construction company becomes unstable in business operation, it is hard to recover even when the market condition turns for the better. This suggests that, to improve business operation of a construction company, internal capacity-building is as important as the market condition and other external circumstances.

An Efficient Routing Algorithm Considering Packet Collisions in Cognitive Radio Ad-hoc Network (CR Ad-hoc Network에서 패킷 충돌을 고려한 효율적인 경로탐색 알고리즘)

  • Kim, Jin-Su;Choi, Jun-Ho;Shin, Myeong-Jin;Lee, Ji-Seon;Yoo, Sang-Jo
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.38B no.9
    • /
    • pp.751-764
    • /
    • 2013
  • In cognitive radio ad-hoc networks, common control channel overload and packet collisions are occured due to indiscriminate broadcasting of control packets. So that the path reliability is reduced and control channel is easily saturated. In this paper, we propose a new routing algorithm considering the probability of appearance of primary user and channel status of neighbor nodes. When the source node needs to transmit a data packet to the destination, it performs route discovery process by exchanging control messages using a control channel in ADOV CR Ad-hoc networks. If any intermediate node doesn't have common data channel with previous node to transmit data, it doesn't rebroadcast control packet. And if it has common data channels with previous node, each node determines channel contribution factor with the number of common channels. Based on the channel contribution factor, each node performs different back-off broadcasting. In addition, each node controls control packet flooding by applying to proposed advanced mode using such as number of available channels and channel stability. With the proposed method, the number of control packets to find the data transmission path and the probability of collision among control packets can be decreased. While the path reliability can be increased. Through simulation, we show that our proposed algorithm reduces packet collisions in comparison with the traditional algorithm.

Estimation of Extreme Sea Levels Reflecting Tide-Surge Characteristics (조석-해일 특성을 반영한 극치해면고 산정)

  • Kang, Ju Whan;Kim, Yang-Seon
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.30 no.3
    • /
    • pp.103-113
    • /
    • 2018
  • Tide-surge characteristics of the West/South domestic coasts were analyzed with a tool of EST (empirical simulation technique). As a result, stations of Incheon, Gunsan, Mokpo and Busan are categorized as tide-dominant coasts, while Yeosu, Tongyoung and Busan are as surge-dominant coasts. In the tide-dominant coasts, extreme sea level of less than 50-yr frequency is formed without typhoon-surge, while only 10-yr extreme sea level is formed in the surge-dominant coasts. As the results of casual condition of extreme sea level formation considering the relative degree of surge on tide, the regional characteristics were detected also. Three methods for estimating the design tide level were compared. The AHHW method shows an unrealistic outcomes of the concern of over estimate design. Furthermore, the probability distribution function method has been concerned as causing missing data if a huge typhoon occurs in a neap tide or a low tide. To cope with these drawbacks, the applicability of the EST method is proved to be suitable especially in tide-dominant coasts.

Statistical Inference for Process Capability Indices and 6 Sigma Qualify Levels (공정능력지수들과 6 시그마 품질수준에 대한 통계적 추론)

  • Cho, Joong-Jae;Sim, Kyu-Young;Park, Byoung-Sun
    • Communications for Statistical Applications and Methods
    • /
    • v.15 no.3
    • /
    • pp.451-464
    • /
    • 2008
  • Six sigma is the rating that signifies "best in clas", with only 3.4 defects per million units or operations. Higher sigma quality level is generally perceived by customers as improved performance by assigning a correspondingly higher satisfaction score. The process capability indices and the sigma level $Z_{st}$ have been widely used in six sigma industries to assess process performance. Most evaluations on process capability indices focus on point estimates, which may result in unreliable assessments of process performance. In this paper, we consider statistical inference for process capability indices $C_p$, $C_{pk}$ and $C_{pm}$. Also, we study better testing procedure on assessing sigma level $Z_{st}$ and capability index $C_{pm}$, for practitioners to use in determining whether a given process is capable. The proposed method is easy to use and the decision making is more reliable. Whether a process is clearly normal or nonnormal, our bootstrap testing procedure could be applied effectively without the complexity of calculation. A numerical result based on our proposed method is illustrated.

Applicability of Robust Decision Making for a Water Supply Planning under Climate Change Uncertainty (기후변화 불확실성하의 용수공급계획을 위한 로버스트 의사결정의 적용)

  • Kang, Noel;Kim, Young-Oh;Jung, Eun-Sung;Park, Junehyeong
    • Journal of Climate Change Research
    • /
    • v.4 no.1
    • /
    • pp.11-26
    • /
    • 2013
  • This study examined the applicability of robust decision making (RDM) over standard decision making (SDM) by comparing each result of water supply planning under climate change uncertainties for a Korean dam case. RDM determines the rank of alternatives using the regret criterion which derives less fluctuating alternatives under the risk level regardless of scenarios. RDM and SDM methods were applied to assess hypothetic scenarios of water supply planning for the Andong dam and Imha dam basins. After generating various climate change scenarios and six assumed alternatives, the rank of alternatives was estimated by RDM and SDM respectively. As a result, the average difference in the rank of alternatives between RDM and SDM methods is 0.33~1.33 even though the same scenarios and alternatives were used to be ranked by both of RDM and SDM. This study has significance in terms of an attempt to assess a new approach to decision making for responding to climate change uncertainties in Korea. The effectiveness of RDM under more various conditions should be verified in the future.

Integration and Decision Algorithm for Location-Based Road Hazardous Data Collected by Probe Vehicles (프로브 수집 위치기반 도로위험정보 통합 및 판단 알고리즘)

  • Chae, Chandle;Sim, HyeonJeong;Lee, Jonghoon
    • The Journal of The Korea Institute of Intelligent Transport Systems
    • /
    • v.17 no.6
    • /
    • pp.173-184
    • /
    • 2018
  • As the portable traffic information collection system using probe vehicles spreads, it is becoming possible to collect road hazard information such as portholes, falling objects, and road surface freezing using in-vehicle sensors in addition to existing traffic information. In this study, we developed a integration and decision algorithm that integrates time and space in real time when multiple probe vehicles detect events such as road hazard information based on GPS coordinates. The core function of the algorithm is to determine whether the road hazard information generated at a specific point is the same point from the result of detecting multiple GPS probes with different GPS coordinates, Generating the data, (3) continuously determining whether the generated event data is valid, and (4) ending the event when the road hazard situation ends. For this purpose, the road risk information collected by the probe vehicle was processed in real time to achieve the conditional probability, and the validity of the event was verified by continuously updating the road risk information collected by the probe vehicle. It is considered that the developed hybrid processing algorithm can be applied to probe-based traffic information collection and event information processing such as C-ITS and autonomous driving car in the future.

Exploring the Reliability of an Assessment based on Automatic Item Generation Using the Multivariate Generalizability Theory (다변량일반화가능도 이론을 적용한 자동문항생성 기반 평가에서의 신뢰도 탐색)

  • Jinmin Chung;Sungyeun Kim
    • Journal of Science Education
    • /
    • v.47 no.2
    • /
    • pp.211-224
    • /
    • 2023
  • The purpose of this study is to suggest how to investigate the reliability of the assessment, which consists of items generated by automatic item generation using empirical example data. To achieve this, we analyzed the illustrative assessment data by applying the multivariate generalizability theory, which can reflect the design of responding to different items for each student and multiple error sources in the assessment score. The result of the G-study showed that, in most designs, the student effect corresponding to the true score of the classical test theory was relatively large after residual effects. In addition, in the design where the content domain was fixed, the ranking of students did not change depending on the item types or items. Similarly, in the design where the item format was fixed, the difficulty showed little variation depending on the content domains. The result of the D-study indicated that the original assessment data achieved a sufficient level of reliability. It was also found that higher reliability than the original assessment data could be obtained by reducing the number of items in the content domains of operation, geometry, and probability and statistics, or by assigning higher weights to the domains of letters and formulas, and function. The efficient measurement conditions presented in this study are limited to the illustrative assessment data. However, the method applied in this study can be utilized to determine the reliability and to find efficient measurement conditions for the various assessment situations using automatic item generation based on measurement traits.

Determinants of age at menarche in Korean elementary school girls (초등학교 여학생의 초경시기와 관련된 결정요인 분석)

  • Kwon, Mi-Kyoung;Seo, Eun Min;Park, Kyong
    • Journal of Nutrition and Health
    • /
    • v.48 no.4
    • /
    • pp.344-351
    • /
    • 2015
  • Purpose: During the recent decades, the age at menarche continued to decline in Korea and worldwide. Prior studies have suggested that early menarche may increase the risk of various social, psychological, and physical health problems in young adolescent girls, but little is known about the determinants associated with early menarche. The purpose of this study is to evaluate independent determinants of early menarche among 5th~6th female graders in South Korea. Methods: Our analysis was conducted in 95 menarcheal girls and 95 age-matched pre-menarcheal girls residing in Daegu, South Korea. Demographic and lifestyle characteristics were collected using survey questionnaires for children and parents. Dietary information was assessed by 2 day~24 hour food records and survey questionnaires, which were completed by both children and their parents. Anthropometric data were obtained from the student health check-ups at the school. Results: A multiple logistic regression analysis using a conditional likelihood method was performed for simultaneous evaluation of several risk factors. There were significant differences in that higher proportion of obesity (OR, odds ratio = 5.60, 95% CI, confidence interval = 1.34~23.42), shorter sleep duration (OR = 0.45, 95% CI = 0.23~0.87), and younger mother's age at menarche (OR = 0.64, 95% CI = 0.44~0.93) were observed in the menarcheal group compared to the pre-menarcheal group. Conclusion: These findings indicate a possible association of sleep duration, mother's menarcheal age, and obesity with age at menarche. A well-planned, prospective cohort study is warranted to examine causal relationship.

An Analysis of Statistics Chapter of the Grade 7's Current Textbook in View of the Distribution Concepts (중학교 1학년 통계단원에 나타난 분포개념에 관한 분석)

  • Lee, Young-Ha;Choi, Ji-An
    • Journal of Educational Research in Mathematics
    • /
    • v.18 no.3
    • /
    • pp.407-434
    • /
    • 2008
  • This research is to analyze the descriptions in the statistic chapter of the grade 7's current textbooks. The analysis is based on the distribution concepts suggested by Nam(2007). Thus we assumed that the goal of this statistic chapter is to establish concepts on the distributions and to learn ways of communication and comparison through distributional presentations. What we learned and wanted to suggest through the study is the followings. 1) Students are to learn what the distribution is and what are not. 2) Every kinds of presentational form of distributions is to given its own right to learn so that students are more encouraged to learn them and use them more adequately. 3) Density histogram is to be introduced to extend student's experiences viewing an area as 3 relative frequency, which is later to be progressed into a probability density. 4) Comparison of two distributions, especially through frequency polygons, is to be an hot issue among educational stakeholder whether to include or not. It is very important when stochastic correlations be learned, because it is nothing but a comparison between conditional distributions. 5) Statistical literacy is also an important issue for student's daily life. Especially the process ahead of the data collection must be introduced so that students acknowledge the importance of accurate and object-oriented data.

  • PDF

A Comparative Study of Curriculum and Mathematics Learning Programme of Lower Grade Between Korea and New Zealand (한국과 뉴질랜드의 초등학교 저학년 교육과정 및 수학학습 프로그램의 비교와 분석)

  • 최창우
    • School Mathematics
    • /
    • v.6 no.1
    • /
    • pp.1-19
    • /
    • 2004
  • Recently, we have been listening such a words, that is, the crisis of public education through the mass communication such as newspaper or broadcasting. This means that we didn't have an enough opportunity to think it over about good education programme which the education of school can be normalized or the design of curriculum in the current problems such as overcrowded class, teacher and poor finance which is not still solved. As we know, it is true that the older generation is familiar with the rote learning which was under the control of behaviorism for about three hundred years. Fortunately, The 7th curriculum which had made public by the ministry of education on 30 Dec. 1997 have changed so many things such as real life based or activity based and so on. But it still leaves something to be desired in reflecting the demand of teachers of field. Taking into account this real situation, I have wondered how they run curriculum and how math learning programme of lower grade is different with ours in New Zealand, etc and so I had tried to find some suggestive points through the comparison of curriculum and text between Korea and New Zealand. But, if we want to compare all the strands of curriculum between two countries, it is too global and so in this paper, we deal with only number and operations(number), measurement, figure(geometry), equation and patter(algebra), probability and statistics(statistics) which are dealt with more comparatively in the lower grade of primary school. Because the main purpose of this paper is a comparison and analysis of the curriculum and math learning program of the lower grade in the primary school between two countries and so we compare global characteristics of education system and curriculum between two countries, at first and then we dealt with the very core part of the content of New Zealand curriculum within the ranges of level 1, 2 and 3 and global characteristics of learning program simultaneously.

  • PDF