• Korean Journal of Construction Engineering and Management
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• v.18 no.6
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• pp.26-37
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• 2017

Preliminary scheduling at the initial stage of planning phase is usually performed with limited information and details. Therefore, the reliability and accuracy of preliminary scheduling is affected by personal experiences and skills of the schedule planners, and it requires enormous managerial effort (or workload). Reusing of historical data of the similar projects is important for efficient preliminary scheduling. However, understanding the structure of historical data and applying them to a new project requires a great deal of experience and knowledge. In this context, this paper propose a framework and methodology for automated preliminary schedule generation based on historical database. The proposed methodology and framework enables to automatically generate CPM schedules for airport projects in the early planning stage in order to enhance the reliability and to reduce the workload by using structured knowledge and experience.

• Journal of the Korean Geophysical Society
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• v.1 no.1
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• pp.3-22
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• 1998

Korea boasts of abundant historical earthquake records of almost 1900 events. The epicenters and intensities of these earthquakes are determined on the basis of descriptions and felt areas of the events. It turns out that most of the earthquakes occurred on major faults or tectonic boundaries of the peninsula except for the northeastern part which had been the least disrupted by tectonic disturbances during the Mesozoic. It appears that the crustal layers of the southern and northwestern parts of the peninsula had been severely ruptured during the Mesozoic disturbances and some of the faults thus generated have been active since. The seismicity of the peninsula had been rather low from the first to the fourteenth century, but unusually high from the fifteenth to the eighteenth century, and have been rather low since. This period of unusually high seismicity of the peninsula coincides with that of the northeastern part of China, suggesting the two areas are seismologically closely connected. It appears that most of the seismicity of the peninsula results from the high stress propagating from the Himalayas where the Eurasian and Indian plates collide. The data file of Korean historical earthquakes is not yet complete and supplementary studies are under way. The main purpose of this paper is to provide the data file of Korean historical earthquakes analyzed up to date for geoscientists and engineers in need of this file.

• Korean Journal of Remote Sensing
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• v.38 no.5_2
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• pp.781-791
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• 2022

It is crucial to provide forest fire risk forecast information to minimize forest fire-related losses. In this research, forecast models of forest fire risk at a mid-range (with lead times up to 7 days) scale were developed considering past, present and future conditions (i.e., forest fire risk, drought, and weather) through random forest machine learning over South Korea. The models were developed using weather forecast data from the Global Data Assessment and Prediction System, historical and current Fire Risk Index (FRI) information, and environmental factors (i.e., elevation, forest fire hazard index, and drought index). Three schemes were examined: scheme 1 using historical values of FRI and drought index, scheme 2 using historical values of FRI only, and scheme 3 using the temporal patterns of FRI and drought index. The models showed high accuracy (Pearson correlation coefficient >0.8, relative root mean square error <10%), regardless of the lead times, resulting in a good agreement with actual forest fire events. The use of the historical FRI itself as an input variable rather than the trend of the historical FRI produced more accurate results, regardless of the drought index used.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.182-184
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• 2012

산업분야에서 이용되는 이력 데이터는 압력, 부피, 온도, 볼트, 전류, 전압 등 각종 제어기나 센서에서 발생하는 입력 정보를 일정 시간 간격으로 수집되는 데이터로, 데이터의 값이 일정하거나 값의 폭이 좁고, 많게는 수만 개의 포인트가 실시간으로 수집, 저장되어지는 대용량의 데이터라는 특징이 있다. 이러한 특성을 지닌 이력 데이터는 이력의 모든 데이터를 저장하지 않고, 전체를 대표하는 데이터의 일부만을 저장함으로써 이력 데이터의 효율적인 관리와 공간효율을 극대화시킬 수 있다. 이러한 이력 데이터를 효과적으로 관리하고, 보관하기 위해 이력 데이터 압축 알고리즘에 대한 개발과 연구가 진행 중이다. 그러나 이미 알려져 있는 이력 데이터 압축 알고리즘과 개발하고 있는 알고리즘의 성능에 대한 평가를 할 수 있는 시뮬레이터는 개인이나 소규모 집단만을 위해 만들어지거나, 공개되지 않고 있어 사용하기에 제한적이다. 이에 이력 데이터 압축 성능평가를 위한 시뮬레이터인 HDCS(Historical Data Compression Simulator)를 설계하고 구현하고자 한다.

• Journal of the Korea Furniture Society
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• v.23 no.2
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• pp.130-143
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• 2012

The rapid increase in apartments of Korea brought about overall changes in the life style, and definitely played the biggest role to convert into western style. Since 1960, furniture has been changed for 50 years along with apartments, but furniture companies and the academic world had insufficient historical materials and lack of study. In addition, considering the changing trend according to residents' life style, the data of furniture industries should be collected to study every year or in 5 years at least. Therefore, this study aims to provide basic data that gives historical materials or design clues based on recent AV equipment-oriented storage furniture in the living room that prioritized design in public space. Accordingly, the study looked into the periodical trends of Korean furniture industries, analyzed 10 furniture companies in Korea which is actively doing business as the sample and arranged key points of periodical changes of furniture in the table, and suggested the conclusion according to the image map, style, color, material, and function.

• Korean Management Science Review
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• v.23 no.2
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• pp.75-91
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• 2006

The purpose of this paper is to propose a new software development cost estimation method using SVR(Support Vector Regression) SVR, one of machine learning techniques, has been attracting much attention for its theoretic clearness and food performance over other machine learning techniques. This paper may be the first study in which SVR is applied to the field of software cost estimation. To derive the new method, we analyze historical cost data including both well-known overseas and domestic software projects, and define cost drivers affecting software cost. Then, the SVR model is trained using the historical data and its estimation accuracy is compared with that of the linear regression model. Experimental results show that the SVR model produces more accurate prediction than the linear regression model.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.232-234
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• 2005

This paper will produce a practical, accurate method for computing the equipment forced outages rate (FOR) based on 10 years of historical equipment outages data. Also, the location and weather conditions on outages are included. The computed FOR are ranked as 4 groups (presumably high, medium, low & very low) depending on the frequency (up to # times per year) and a consistent framework for transmission reliability performance table is developed based on these groupings. Our intent is to use this framework as guidelines for contingency analysis criteria in system planning / operation departments. The concepts are illustrated on the 2005 KEPCO power system.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.209-213
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• 2008

재현기간이 수백년 이상인 이상홍수의 초과확률을 추정하기 위해서는 재현기간 이상의 홍수자료를 이용해 내삽(interpolation)을 해야 하지만 현재 우리나라의 체계적(systematic) 관측자료 기간은 이에 훨씬 미치지 못한다. 따라서, 역사 자료(historical data)를 이용해 자료 길이를 확장하는 방법, 홍수자료에 비해 비교적긴 강우자료와 유출 모형에 의한 합성자료를 이용하는 방법 등이 사용되어 왔다. 본 연구에서는 역사 자료와 체계적 관측자료를 효율적으로 결합할 수 있는 EMA(Expected Moment Algorithm) 기법을 연구하였다. EMA는 Cohn 등(1997)에 의해 제안된 방법으로 미국의 공식 분포인 LP3(Log-Pearson type 3) 분포를 대상으로 반복 계산을 통해 매개변수를 추정하는 기법으로서 본 연구에서는 LP3 분포 대신에 최근 국내 홍수빈도해석 시 많이 쓰이고 있는 GEV(Generalized Extreme Value) 분포를 대상으로 EMA 절차를 이론적으로 유도하였다.

• Water for future
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• v.12 no.2
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• pp.63-69
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• 1979

The sequences of monthly streamflows constitute a non-statonary time series. The purely stochastic model has been applied to data generation of non-stationary time series. Tow different mothods--single site and multisite generation--have been used on the hydrologic time series. In this study the synthetic generation method by bivariate analysis, studied by Thomas Fiering, one of multi-site models, has been applied to the historical data on monthly streamflows at two sites in Nakdong River, and also for validity of this model the single site Thomas Fiering model applied. Through statistical analysis it has been shown that the performance of bivariate Thomas Fiering model was better than that of the other. By comparison of mean and standard deviaion between the historical and the generated, and cross correlogram interpretation, it has been known that the model used herein has good performance to simultaneously generate the monthly streamflows at two sites in a river hasin.

• ETRI Journal
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• v.24 no.3
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• pp.226-238
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• 2002

A spatial object changes its states over time. However, existing spatial and temporal database systems cannot fully manage time-varying data with both spatial and non-spatial attributes. To overcome this limitation, we present a framework for spatio-temporal databases that can manage all time-varying historical information and integrate spatial and temporal relationship operators into the select statement in SQL3. For the purpose of our framework, we define three referencing macros and a history aggregate operator and classify the existing spatial and temporal relationship operators into three groups: exclusively spatial relationship operators, exclusively temporal relationship operators, and spatio-temporal common relationship operators. Finally, we believe the integration of spatial and temporal relationship operators into SQL3 will provide a useful framework for the history management of time-varying spatial objects in a uniform manner.