• The Journal of Engineering Geology
• /
• v.21 no.4
• /
• pp.361-367
• /
• 2011

The uniaxial compressive strength (UCS) is an important factor in the design and construction of surface and underground structures. However, the method employed to measure UCS is time consuming and expensive to apply in the field. Therefore, we developed a model to estimate UCS based on a few properties using linear regression analysis, which is a statistical method. To develop the model, valid factors from the test results were selected from a correlation analysis using a statistical program, and the model was formulated by linear regression based on the relationships among factors. UCS estimates derived from the model were compared with the results of UCS tests, to assess the reliability of the model. The relationship between rock properties and UCS indicates that the factors with the greatest influence on UCS are point load strength and shape facto r. The UCS values obtained using the model are in good agreement with the results of the UCS test. Therefore, the developed model may be used to estimate the UCS of rocks in regions with similar conditions to those of the present study area.

• The Journal of Engineering Geology
• /
• v.22 no.2
• /
• pp.207-221
• /
• 2012

A statistical analysis of time series of water level at 27 groundwater monitoring wells was conducted to analyze the surface water-groundwater connectivity in the wide alluvial plains surrounding the Nakdong River, Korea. Change in groundwater level is strongly related to river water level, yielding an average cross-correlation coefficient of 0.601, which is much higher than that between rainfall and groundwater level (0.125). Principal component analysis of groundwater level indicates that wells in the study area can be classified into two groups: wells in Group A are located close to a river, have water levels closely related to river level, and generally show a large increase in groundwater level during heavy rainfall. On the other hand, wells in Group B located far from a river are relatively less related to river level. Including hydrologic and statistical analyses, geochemical analysis and temperature monitoring are additionally required to reveal the relationship between surface water level and groundwater level, and to assess the possibility of groundwater flooding.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.4
• /
• pp.255-263
• /
• 2016

This study conducted empirical tests on contemporary finance theories for corporate cash holdings, such as trade-off, pecking order, and agency theory. There is ongoing debate on the possibility of excess cash savings by domestic firms, including chaebols in the Korean capital markets. Thus, it may be worthy to identify any financial characteristics based on each aforementioned theory as an extension of previous studies on similar subjects. Two primary hypotheses were postulated and tested, and the following empirical results were obtained. First, principal component analysis (PCA) provides evidence that nine out of the twenty explanatory variables showed a significant influence on the level of corporate cash holdings, such as cash conversion cycle in trade-off theory and leverage in pecking order theory. Second, the chaebol firms that decreased cash holdings after global financial turmoil may be affected by financial factors that include investment opportunities and foreign ownership according to the PCA. The results may reinforce the outcomes derived from previous research on corporate cash holdings. Based on the robust results, large firms in advanced or emerging capital markets could approach the optimal level of the cash reserves.

• Proceedings of the Korean Information Science Society Conference
• /
• 2003.10b
• /
• pp.415-417
• /
• 2003

본 논문에서는 휴대폰에서 실시간으로 사용할 수 있는 GIS 기반의 약도를 생성하는 기법을 소개한다. 휴대폰의 출력 창은 크기가 제한되어, 자세한 도로 정보들이나 건물 정보 등의 GIS 정보를 모두 출력 창에 표현하면 사용자들이 인식하기가 매우 어렵다. 그러므로, 출력창의 크기에 맞춘 간략한 약도를 제공하여 사용자들이 지리 정보를 손쉽게 활용할 수 있도록 도와주자는 것이다. 기존의 GPS와 지리 정보를 이용한 경로 탐색 및 안내 장비는 차량 운전자를 위한 도로 중심의 지리 정보를 제공한다. 우리나라 도로 환경에서는 휴대폰을 가진 보행자가 장소 찾기에 필요한 지리 정보를 원하는 경우도 않다. 그러므로 본 연구에서는 도보 통행자 및 대중교통 사용자들이 이용하기 편리하도록 지하철역이나 버스 정류장, 대형건물과 같은 이정표를 중심으로 하고. 장소 찾기에 필요한 도로만을 출력 창에 나타내어 단순화된 지리정보를 제공하고자 한다. 또한, 기존에 사용하던 방위 개념 중심의 지도들을 가지고, 지도 읽기에 익숙하지 않은 일반 보행자들이 길 찾기에 바로 사용하는 것은 쉽지 않다. 그러므로 수직 개념을 이용한 단순화된 도로 표현 기법을 사용하여 일반인도 쉴게 지도를 보고 길을 찾을 수 있도록 하였다. GIS 정보 중에서 필요로 하는 도로들을 선택하여 그 경로들을 수직선과 수평선에 가깝게 변형하고, 불필요한 도로를 생략, 지도를 단순화하였다. 또한 포함되어 있던 많은 정보들 중에서 일반적으로 보행자들이 길을 찾아갈 때에 참고하는 정보들을 제외한 나머지 정보들을 생략함으로써, 불필요한 정보로 인한 지도의 복잡도를 줄이고, 지리 정보의 가독성을 향상시켰다. 본 연구의 결과를 활용하면 휴대폰의 출력 창에는 이정표 중심의 약도를 표현할 수 있으므로, 약도 정보를 실시간으로 서비스할 수 있을 것으로 기대된다.성뿐만 아니라 보안성을 중요하게 생각하였으며, 앞으로 보안 관련 소프트웨어 개발에 사용될 수 있는 도구들이 가이드 라인에 대한 정보를 제공한다.용할 수 있는지 세부 설계를 제시한다.다.으로서 hemicellulose구조가 polyuronic acid의 형태인 것으로 사료된다. 추출획분의 구성단당은 여러 곡물연구의 보고와 유사하게 glucose, arabinose, xylose 함량이 대체로 높게 나타났다. 점미가 수가용성분에서 goucose대비 용출함량이 고르게 나타나는 경향을 보였고 흑미는 알칼리가용분에서 glucose가 상당량(0.68%) 포함되고 있음을 보여주었고 arabinose(0.68%), xylose(0.05%)도 다른 종류에 비해서 다량 함유한 것으로 나타났다. 흑미는 총식이섬유 함량이 높고 pectic substances, hemicellulose, uronic acid 함량이 높아서 콜레스테롤 저하 등의 효과가 기대되며 고섬유식품으로서 조리 특성 연구가 필요한 것으로 사료된다.리하였다. 얻어진 소견(所見)은 다음과 같았다. 1. 모년령(母年齡), 임신회수(姙娠回數), 임신기간(姙娠其間), 출산시체중등(出産時體重等)의 제요인(諸要因)은 주산기사망(周産基死亡)에 대(對)하여 통계적(統計的)으로 유의(有意)한 영향을 미치고 있어 $25{\sim}29$세(歲)의 연령군에서, 2번째 임신과 2번째의 출산에서 그리고 만삭의 임신 기간에, 출산시체중(出産時體重) $3.50{\sim}3.99kg$사이의 아이에서 그 주산기사망률(周産基死亡率)이 각각 가장 낮았다. 2. 사산(死産)과 초생아사망(初生兒死亡)을 구분(區分)하여 고려해 볼때 사산(死産)은 모성(母性)의 임신력(姙娠歷)과 매우 밀접한 관련이 있는 것으로 사료(思料)되었고 초생아사망(初生兒死

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.04b
• /
• pp.145-147
• /
• 2004

본 논문에서는 무선인터넷 환경에 적합한 개인화된 상품추천에이전트를 제안한다. 기존에 유선인터넷상의 많은 개인화 추천시스템에서는 초기 사용자 모델링을 위해 사용자에게 수많은 질의를 하고 응답을 요구하였다. 그러나 이러한 방식은 무선인터넷 환경에서 정보 전송량에 따른 높은 사용요금을 고려할 때 적용하기 힘든 방식이다. 본 제안 시스템은 사용자의 Social data률 이용하여 사용자를 비슷한 연령과 성별 그룹으로 나누고, 해당 그룹에서 구매율이 높은 상품을 우선 제시한 후, 사용자 행동을 모니터링 하여 암시적(Implicit)피드백을 통해 프로파일을 생성함으로써, 번거로운 질의-응답 과정 없이도 초기 사용자 모델링을 수행할 수 있다. 프로파일 생성 이후에는 이를 기반으로 하여 사용자몰 유사한 취향을 가진 그룹으로 다시 군집화한 후 협력적 추천을 하게 되며, 프로파일에는 해당 상품의 최종 카테고리명과 키워드를 수집함으로써, 상품의 브랜드와 규격정보를 반영한 추천이 가능하다. 또한 추천 상품과 사용자의 구매데이터와의 비교를 수행하여 사용자가 해당상품을 구매하였을 경우, 상품에 대한 취향정보는 그대로 유지하고 관련 상품을 추천하되, 구매한 상품이 중복 추천되지 않도록 하였다. 시스템 평가를 위해 프로토타입을 구현하여, 다수의 사용자에게 시스템을 이용하며 관심품목을 체크하도록 하였고. 추천횟수가 반복되며 히트율이 증가하는 결과를 통해 시스템의 학습속도와 성능을 평가하였다. 그리고 쇼핌몰에서 구매경험이 있는 사용자의 기존 구매데이터와 Social data를 이용한 초기 제시상품을 역으로 비교하여 오랜 시간과 비용 발생 없이도 초기 프로파일 생성의 유효성을 증명하였다. 포함하는 XML 질의에 대해서도 웹에서 캐쉬를 이용한 처리가 효율적임을 확인하였다.키는데 목적이 있다.RED에 비해 향상된 성능을 보여주었다.웍스 네트워크상의 다양한 디바이스들간의 네트워크 다양화와 분산화 기능을 얻을 수 있었고, 기존의 고가의 해외 솔루션인 Echelon사의 LonMaker 소프트웨어를 사용하지 않고도 국내의 순수 솔루션인 리눅스 기반의 LonWare 3.0 다중 바인딩 기능을 통해 저 비용으로 홈 네트워크 구성 관리 서버 시스템 개발에 대한 비용을 줄일 수 있다. 기대된다.e 함량이 대체로 높게 나타났다. 점미가 수가용성분에서 goucose대비 용출함량이 고르게 나타나는 경향을 보였고 흑미는 알칼리가용분에서 glucose가 상당량(0.68%) 포함되고 있음을 보여주었고 arabinose(0.68%), xylose(0.05%)도 다른 종류에 비해서 다량 함유한 것으로 나타났다. 흑미는 총식이섬유 함량이 높고 pectic substances, hemicellulose, uronic acid 함량이 높아서 콜레스테롤 저하 등의 효과가 기대되며 고섬유식품으로서 조리 특성 연구가 필요한 것으로 사료된다.리하였다. 얻어진 소견(所見)은 다음과 같았다. 1. 모년령(母年齡), 임신회수(姙娠回數), 임신기간(姙娠其間), 출산시체중등(出産時體重等)의 제요인(諸要因)은 주산기사망(周産基死亡)에 대(對)하여 통계적(統計的)으로 유의(有意)한 영향을 미치고 있어 $25{\sim}29$세(歲)의 연령군에서, 2번째 임신과 2번째의 출산에서 그리고 만삭의 임신 기간에, 출산시체중(出産時體重) $3.50{\sim}3.99kg$사이의 아

• Korean Journal of Plant Resources
• /
• v.27 no.2
• /
• pp.188-193
• /
• 2014

The sap outflow characteristics of Juglans sinensis and J. mandshurica were investigated to evaluate the optimum pruning period of walnut tree that there is a sap spill on dormant. The total period of sap outflow were 34 days for both J. sinensis and J. mandshurica. Total amount of sap outflow per tree in J. sinensis and J. mandshurica were 2,922 mL/tree and 3,135 mL/tree, respectively and the period of sap outflow and non sap outflow between two species were similar. ANOVA analysis showed that the amount of sap outflow was significant differences with day of sap outflow but there were no significant differences between species. From the correlation analysis between air-temperature and sap outflow, daily minimum temperature showed a positive correlation at the 1% level of significance (r=0.56 and r=0.46) for both J. sinensis and J. mandshurica. When branch of walnut tree that diameter is 5 cm cut on the period of sap outflow, the sap flowed down the longest period (48 days) but the sap outflow was not observed after budburst. Therefore, our study supported that the pruning have to avoid the period of sap outflow to reduce sap outflow of walnut tree.

• The Journal of the Korea Contents Association
• /
• v.21 no.12
• /
• pp.107-118
• /
• 2021

One of the debates regarding the college admission systems is about which admissions screening works as a mechanism for social mobility, between early and regular admissions. This study attempted to contribute to related discussions by analyzing the income level of college admissions students according to the admissions screening (early vs. regular admissions) using data from the third year survey of the Korean Education & Employment Panel II (KEEP II). Analyzing the dataset, we found that parental income was almost the same between students admitted from early and regular admissions. To be specific, average monthly parental income was 586.4 million Korean Won for students admitted from early admission while it was 585.4 million Korean Won for those admitted from regular admission, which means that the difference between the two was neither practically nor statistically significant. Applying the chi-square test, we tested whether the relationship between parental income and types of college admissions and found no statistical significance. Finally, categorizing colleges where students are admitted by ranking, we compared parental incomes among students. We found that parental income was higher for top-ranked universities, and that parental income was higher for students admitted from early admission. We concluded that early admission can possibly be an admission system for "well-offs" between the two, and that early admission may not be working as a pathway to facilitate social mobility compared to the regular admissions.

• Journal of the Korea Society of Computer and Information
• /
• v.28 no.3
• /
• pp.189-196
• /
• 2023

This paper analyzes the level of satisfaction of two groups of teachers who were educated about artificial intelligence using App Inventor. The participants were 13 pre-service and 9 in-service elementary school teachers and the data was collected using a questionnaire. As a result of the study, in-service teachers were all more satisfied than pre-service teachers in terms of interest, difficulty, and participation in the education. In addition, the questions investigating whether education helped motivate learning of artificial intelligence and whether there is a willingness to apply it to elementary classes in the future were also more positive for in-service teachers than for pre-service teachers. In general, pre-service teachers had somewhat more negative views than in-service teachers, but they were more positive than in-service teachers in terms of whether the education helped improve their understanding of artificial intelligence and whether they were willing to participate in additional education. Analysis of the Mann-Whitney test to see if there was a significant difference in satisfaction between the two groups showed no significance. This may be because most of the students in the two groups already had block-type or text-type programming experience, so they were able to participate in the education without any special resistance or difficulty with App Inventor, resulting in high levels of satisfaction from both groups. The results of this study can provide basic data for the future development and operation of programs for artificial intelligence education for both pre-service and in-service elementary school teachers.

• Journal of Korea Water Resources Association
• /
• v.57 no.5
• /
• pp.311-320
• /
• 2024

Climate change has been intensifying drought frequency and severity. Such prolonged droughts reduce reservoir levels, thereby exacerbating drought impacts. While previous studies have focused on optimizing reservoir operations using historical data to mitigate these impacts, their scope is limited to analyzing past events, highlighting the need for predictive methods for future droughts. This research introduces a novel approach for predicting minimum inflow at the Seomjingang dam which has experienced significant droughts. This study utilized the Stochastic Analysis Modeling and Simulation (SAMS) 2007 to generate inflow sequences for the same period of observed inflow. Then we simulate reservoir operations to assess firm yield and predict minimum inflow through synthetic inflow analysis. Minimum inflow is defined as the inflow where firm yield is less than 95% of the synthetic inflow in many sequences during periods matching observed inflow. The results for each case indicated the firm yield for the minimum inflow is on average 9.44 m³/s, approximately 1.07 m³/s lower than the observed inflow's firm yield of 10.51 m³/s. The minimum inflow estimation can inform reservoir operation standards, facilitate multi-reservoir system reviews, and assess supplementary capabilities. Estimating minimum inflow emerges as an effective strategy for enhancing water supply reliability and mitigating shortages.

• Korean Journal of Environmental Biology
• /
• v.41 no.4
• /
• pp.720-734
• /
• 2023

To understand the spatiotemporal distribution pattern of zooplankton and the environmental factors influencing zooplankton abundance in Gomso Bay, major harvesting area of Manila clam (Venerupis philippinarum) in South Korea, zooplankton sampling was conducted four times in autumn (October 2022), winter (January 2023), early spring (March 2023), and spring (May 2023). Among the environmental factors of Gomso Bay, water temperature, chlorophyll a concentration (Chl-a), dissolved oxygen (DO), and pH observed different patterns, while salinity and suspended particulate matter(SPM) showed no significant statistical differences between the survey periods. The zooplankton in Gomso Bay occurred 33, 29, 27, and 29 taxonomic groups during each respective survey period. In October 2022 and May 2023, arthropod plankton were dominated, while in January and March 2023, protozoa were primarily dominant. Among the Arthropods, copepods including Acartia hongi, Paracalanus parvus s. l., Corycaeus spp., and Oithona spp. commonly found along Korean coastal areas of the Yellow Sea, were dominated. Cluster analysis based on zooplankton abundance indicated a single community (stable condition) in each season, attributed to low dissimilarity distances, while three distinct clusters (autumn, winter-early spring, spring) between seasons indicated a highly seasonal environment in Gomso Bay.