• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.3
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• pp.291-302
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• 2005

Due to the importance of the parameter in structural response, the uncertain elastic modulus was located at the center of stochastic analysis, where the response variability caused by the uncertain system parameters is pursued. However when we analyze the so-called stochastic systems, as many parameters as possible must be included in the analysis if we want to obtain the response variability that can reach a true one, even in an approximate sense. In this paper, a formulation to determine the statistical behavior of in-plane structures due to multiple uncertain material parameters, i.e., elastic modulus and Poisson's ratio, is suggested. To this end, the polynomial expansion on the coefficients of constitutive matrix is employed. In constructing the modified auto-and cross-correlation functions, use is made of the general equation for n-th moment. For the computational purpose, the infinite series of stochastic sub-stiffness matrices is truncated preserving required accuracy. To demons4rate the validity of the proposed formulation, an exemplary example is analyzed and the results are compared with those obtained by means of classical Monte Carlo simulation, which is based on the local averaging scheme.

• Korea journal of population studies
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• v.19 no.2
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• pp.47-76
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• 1996

This study was carried out to provide the basic information for the implementation of population quality policies by analyzing fetal life. The outcomes and process of all the pregnancies of women with spouses living in Gapyung-gun, Kyunggi province from November 3, 1993 through December 31, 1995 were analyzed. The results of the study are as follows: According to the fetal life table, the estimated probability of pregnancy outcome showed 53.5% of live birth, 14.5% of fetal death, 32.0% of induced abortion, which resulted in 46.5% of pregnancy wastage throughout gestation period. The curve of the estimated probability of pregnancy outcome by gestation weeks showed L shape in case of total pregnancy rate, induced abortion rate and fetal death rate. The estimated probability of fetal death was 21.9% in case that the induced abortion was excluded, which was 7.4% higher than the case that induced abortion was included. The expected duration of pregnancy was 22.9 weeks until the fourth week of gestation and then started to become the highest, 26.6 weeks at the tenth week. At the 11th week, it declined to decrease to 26.4 weeks. This is attributed to the fact that the pregnancy wastage including fetal death and induced abortion occurred in the early period of pregnancy. The establishment of appropriate policies to cope with this situation are needed.

• Education of Primary School Mathematics
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• v.16 no.2
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• pp.147-162
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• 2013

This is an in-dept case study that extract the problems showing remarkable gender gap in 6th graders and analyze the difference between boys and girls in the process of problem solving. This study can be summarized as the following. First, according to the result of basic study, the parts are divided into measurement, probability and statistics and regularity. And then test problems and face-to-face talk contents are developed. Second, the distinct features between boys and girls, follow-up study and face-to-face talk. As a result, five characteristics of gender gap are selected. Through the results of this study, the improvement of teaching & learning development and evaluation considering gender is expected in the classrooms of elementary schools.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.11a
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• pp.118-126
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• 2000

동양의학에서 인체의 주된 생리 정보는 체질과 맥진에서 얻어질 수 있다 체질은 선천적인 오장 육부 기능에 대한 정보를 제공한다. 체질에 대한 판단은 얼굴형상, 맥진, 사주 등의 방법에 의한다. 반면에 진맥은 현재의 오장육부의 건강 상태를 나타낸다. 오장육부의 생체정보는 인체경락의 전기 전도도를 측정하는 방법에 의해서도 얻어질 수 있으나 본 논문에서는 진맥에의한 방법만을 토론한다. 체질과 진맥 정보는 치병에 있어서 처방의 기간과 강도를 결정 할 수 있는 결정적인 변수이다. 이 두가지 정보 중에서 하나라도 결핍될 경우 병에 대한 효율적인 대응이 어려워진다. 그 이유는 처방의 강약 조절이 어렵고 그 결과 다른 부작용 유발가능성이 크다. 본 논문에서는 진맥이론의 일반적 전개를 위하여 음양오행 성질의 과학적인 정의를 기초로 하였다. 구체적인 맥상의 판단에는 (1) 음의 맥과 양의 맥의 절대적 크기와 상대적 비(즉 음양의 강도와 비), (2) 오행의 성질에 기초한 맥의 형상, 그리고 (3) 맥의 느낌이나 성질등 3가지 정보를 종합한 방법으로 맥상을 파악한다. 이러한 맥진기술 이론은 분류방법이 간단할 뿐만아니라 이론이 일반적이다. 그래서 한의학의 전문가는 물론이고 일반인 모두 쉽게 익혀 덜인의 건강상태를 스스로 파악하는 것이 가능하다. 진맥기 제작의 기년 이론으로서 역할을 할 수 있다. 오행이론에 기초 할 경우 맥상은 5가지 대표적인 맥으로 분류된다. 맥의 이름은 황제내경에 제시된 한의학적인 이름과 함께 맥상을 쉽게 유추 할 수 있는 실생활적인 이름을 병용하였다. 예를 들어 위장이 약할 때 나타나는 홍맥을 진빵같이 부드러운 맥으로, 폐가 나쁠 때 나오는 흩어지는 모맥을 도우너츠형 연기맥으로, 신장이 나쁠 때 나오는 단단한 석맥을 고구마형상의 돌덩어리맥으로, 간이 나쁠 때 나오는 긴장된 현맥을 팽팽한 고무줄맥으로 그리고 심장이 나쁠 때 나오는 작고 연한 구맥을 튀어오르는 물방울맥으로 명명하였다. 이외에 진맥에 의하여 인체의 한열이나 지삭 부침등의 정보가 가능하며, 이러한 정보는 고혈압이나 중풍 확률, 비만 가능성 지수, 골다공증 선행지수 그리고 심장기능 파악(불전맥이나 대맥) 등 다양한 인체 정보를 파악하는 데 응용될 수 있음을 강조한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.175-175
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• 2018

우리나라에서 발생하는 대규모 자연재해의 상당부분은 강우에 의한 홍수피해이다. 최근 이러한 홍수피해는 기후변화와 더불어 극한강우 현상의 빈발에 의한 새로운 재해양상으로 전개되고 있으며, 이에 따라 정부에서도 재해발생시 원상복구의 개념이 아닌 항구복구의 개념으로 복구사업을 수행하고 있다. 그러나 설계에 기후변화에 대한 영향을 반영하고 있지 못하기 때문에 기후변화에 의하여 미래에 발생할 극한강우로 반복적인 피해가 예상되고 있으므로 기존의 방재성능목표 강우량의 설정 방법에 대한 개선이 필요하다. 전 세계적으로 이러한 기후변화에 의한 현상을 모의하기 위한 연구로 전지구기후모델(Global Climate Model, 이하 GCM)과 지역기후모델(Reginal Climate Model, 이하 RCM)을 사용하고 있다.우리나라 기상청에서도 CMIP5 국제사업의 표준 실험체계를 통해 전지구 기후변화 시나리오 산출을 위해서 영국 기상청 해들리센터의 GCM인 HadGEM2-AO를 도입하였다. 또한 한반도 기후변화 시나리오를 산출하기 위해 HadGEM3-RA 모형을 이용하여 전지구 기후변화 시나리오를 역학적으로 상세화하고 이를 한반도에 대해 12.5km 공간 해상도로 일 자료를 제공하고 있다. 하지만 유역규모 혹은 지점규모에서 사용하기 위해서는 이러한 일자료의 시 공간적인 상세화기법이 요구된다. 본 연구에서는 기후변화를 고려한 방재성능목표 강우량 개선 방향을 제안하기 위해 다양한 연구단에서 도출된 상세화 결과를 수집하고 비교분석을 통해 기후변화를 고려하고자 하였다. 다양한 연구기관에서 생산된 미래 확률 전망을 살펴본 결과, 동일한 GCM자료를 사용하더라도 상세화 방법론에 따라 서로 다른 결과가 도출되는 것을 확인하였다. 미래 예측의 불확실성을 고려하면 특정한 방법론이 우수하다고 평가하기는 어려움에 따라 앙상블 평균을 활용한 개선방향을 제안한다. 본 연구의 결과는 전국 지자체의 강우특성만을 고려한 것으로, 연안지역의 경우 해수면 상승을 고려하여 추가적인 대책이 필요할 것으로 판단된다.

• Journal of Educational Research in Mathematics
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• v.15 no.4
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• pp.445-459
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• 2005

Statistics education is considered within the mathematics curriculum and, thus, can be integrated into other areas of mathematics. However, statistical concepts and thinking skills have to be considered as very different from those of other areas. It is possible to make statistics more meaningful for the learner by making definitions or explanations of concepts in textbooks more clear and consistent. In 'Math I' and 'Probability & Statistics' of the 7th curriculum, the definitions of sample standard deviation are different, which might confuse students. In this study, firstly, some issues relevant to sample standard deviation concept are discussed through the analysis in terms of didactical situation and curriculum. Secondly, the characteristics of sample standard deviation concept as a scholarly knowledge are examined. Finally, the characteristics of didactic transposition of sample standard deviation concept in Japanese, American, and British textbooks are investigated and some suggestions are elicited.

• Journal for History of Mathematics
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• v.25 no.4
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• pp.53-67
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• 2012

Today, it is necessary to calculate orbits with high accuracy in space flight. The key words of Poincar$\acute{e}$ in celestial mechanics are periodic solutions, invariant integrals, asymptotic solutions, characteristic exponents and the non existence of new single-valued integrals. Poincar$\acute{e}$ define an invariant integral of the system as the form which maintains a constant value at all time $t$, where the integration is taken over the arc of a curve and $Y_i$ are some functions of $x$, and extend 2 dimension and 3 dimension. Eigenvalues are classified as the form of trajectories, as corresponding to nodes, foci, saddle points and center. In periodic solutions, the stability of periodic solutions is dependent on the properties of their characteristic exponents. Poincar$\acute{e}$ called bifurcation that is the possibility of existence of chaotic orbit in planetary motion. Existence of near exceptional trajectories as Hadamard's accounts, says that there are probabilistic orbits. In this context we study the eigenvalue problem in early 20th century in three body problem by analyzing the works of Darwin, Bruns, Gyld$\acute{e}$n, Sundman, Hill, Lyapunov, Birkhoff, Painlev$\acute{e}$ and Hadamard.

• Asia Marketing Journal
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• v.7 no.1
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• pp.21-42
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• 2005

Customer Relationship Management (CRM) is a corporate marketing strategy maintaining and managing customers. And with CRM companies maximize the customer's value through a series of processes of new customer retention, VIP customer retention, customer value increase, potential customer activation, and customers for lifetime by collecting the customer information and taking advantage of it effectively. In particular, as the competitive environment is changing rapidly and getting more intense, maintaining the customer retention through customer churn management becomes more important in order to increase the customer value for maximizing the company's profit and to build up the relationship with customers. For example, the financial industry has managed the customer churn with the concept of customer segmentation. Recently the customer retention and churn management is becoming increasingly important in all business fields as well as financial industry since the companies expect the effect of preventing the customer churn by identifying characteristics of customers. However, despite the increasing interest and importance of the management of the customer churn, not many of studies are systematically executed by analyzing the data of customer churn. In this study we analyze the actual data of CRM activities for the customer retention, specifically the data of TV home-shopping. By doing so, we hope to identify the differences of demographic attributes and transaction specific characteristics in consumer behaviors between the churning customer and the retained customers. In addition, we try to find out the variables which can impact the churning of the customers and to predict the churn rate of individual customer through our proposed model of customer churn. In the end, based on our findings we suggest the possible marketing strategies for TV home-shopping companies.

• The Transactions of the Korea Information Processing Society
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• v.7 no.10
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• pp.3138-3147
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• 2000

EC(Electronic Commerce) which is cone the virtual space through Internet, has the advantage of time and space. On the contrary, it also has weak point like security probelm because anybody can easily access to the system due to open network attribute of Internet. Theretore, we need the solutions that protect the EC security problem for safe and useful EC activity. One of these solution is the implemonlation of a strong cipher algorithm. YK2(YoungKu Kang) cipher algorithm proposed in this paper is advantage for the EC security and it overcomes the limit of the current 6/1 bits block cipher algorithm using 128 bits key length for input, output, encryption key and 32 rounds. Moreover, it is degigned for the increase of time complexity and probability calculation by adapting more complex design for key scheduling regarded as one of the important element effected to enciyption.

• The KIPS Transactions:PartB
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• v.9B no.5
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• pp.625-634
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• 2002

In this paper, we conducted various experiments with Bayesian networks in order to analyze clinical data of infertility patients. With these experiments, we tried to find out inter-dependencies among important factors playing the key role in clinical pregnancy, and to compare 3 different kinds of Bayesian network classifiers (including NBN, BAN, GBN) in terms of classification performance. As a result of experiments, we found the fact that the most important features playing the key role in clinical pregnancy (Clin) are indication (IND), stimulation, age of female partner (FA), number of ova (ICT), and use of Wallace (ETM), and then discovered inter-dependencies among these features. And we made sure that BAN and GBN, which are more general Bayesian network classifiers permitting inter-dependencies among features, show higher performance than NBN. By comparing Bayesian classifiers based on probabilistic representation and reasoning with other classifiers such as decision trees and k-nearest neighbor methods, we found that the former show higher performance than the latter due to inherent characteristics of clinical domain. finally, we suggested a feature reduction method in which all features except only some ones within Markov blanket of the class node are removed, and investigated by experiments whether such feature reduction can increase the performance of Bayesian classifiers.