• Title/Summary/Keyword: problem analysis

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Development of Survey Tool for the Scientific Character of Elementary Student (초등학생을 위한 과학인성 검사 도구 개발)

  • Nam, Ilkyun;Im, Sungmin
    • Journal of The Korean Association For Science Education
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    • v.38 no.6
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    • pp.825-838
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    • 2018
  • The purpose of this study is to develop a survey tool of scientific character for elementary student which connects science education and character education effectively by figuring out traits of elementary students' character being presented in teaching and learning context of elementary school science. For this, we adapted the theocratical model from the previous research which defined scientific character as the competencies being able to practice in concrete teaching and learning context of science. Based on this model, we developed the survey tool as 'Scientific Character Inventory for Elementary Student' to assess elementary students' scientific character as the competences to practice the virtues being pursued in the context of elementary school science and verified its reliability and validity. As a result of an exploratory and confirmatory factor analysis, we confirmed all the items could be summarized into 28 items and eight constructs such as scientific problem-solving, self-management, self-reflection, communication, interpersonal skill, community participation, global citizenship, and environmental ethics awareness. We found that minimum reliability coefficient of constructs was over than 0.5 and reliability coefficient of the total items was 0.878. And also, there was modest relationship between each construct and the total score of scientific character. These results show that the developed survey tool can be useful in evaluating the effectiveness of science character education. This study is meaningful in that it systematically reveals constructs of scientific character which can be raised in concrete context of science teaching and learning so as to suggest the survey tool to assess this.

A Comparison Analysis on the Efficiency of Solar Cells of Shingled Structure with Various ECA Materials (다양한 ECA 소재를 활용한 shingled 구조의 태양전지 효율 비교 분석)

  • Jang, Jae Joon;Park, Jeong Eun;Kim, Dong Sik;Choi, Won Seok;Lim, Donggun
    • Journal of the Korean Solar Energy Society
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    • v.39 no.4
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    • pp.1-9
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    • 2019
  • Modules using 6 inch cells have problems with loss due to empty space between cells. To solve this problem made by shingled structure which can generate more power by utilizing empty space by increasing the voltage level than modules made in 6inch cell. Thus, in this paper, the c-Si cutting cells were produced using nanosecond green laser, and then the ECA was sprayed and cured to perform cutting cell bonding. Three types of ECA materials (B1, B2, B3) with Ag as the main component were used, and experimental conditions varied from 5 to 120 seconds of curing time, 130 to $210^{\circ}C$ of curing temperature, and 1 to 3 of curing numbers. As a results of experiments varying curing time, B1 showed efficiency 19.88% in condition of 60 seconds, B2 showed efficiency 20.15% in 90 seconds, and B3 showed efficiency 20.27% in 60 seconds. In addition, experiments with varying curing temperature, It was confirmed highest efficiency that 20.04% in condition of $170^{\circ}C$ with B1, 20.15% in condition of $150^{\circ}C$ with B2, 20.27% in condition of $150^{\circ}C$ with B3. These are because the Ag particles are densely formed on the surface to make the conduction path. After optimizing the conditions of temperature and curing time, the secondary-tertiary curing experiments were carried out. as the structural analysis, conditions of secondary-tertiary curing showed cracks that due to damp heat aging. As a result, it was found that the ECA B3 had the highest efficiency of 20.27% in condition of 60 seconds of curing time, $150^{\circ}C$ of curing temperature, and single number of curing, and that it was suitable for the manufacture of Solar cell of shingled structure rather than ECA B1 and B2 materials.

Analytical Research on Dynamic Behavior of Steel Composite Lower Railway Bridge (강합성 하로 철도교의 동적거동에 대한 해석적 연구)

  • Jeong, Young-Do;Koh, Hyo-In;Kang, Yun-Suk;Eom, Gi-Ha;Yi, Seong-Tae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.1
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    • pp.27-35
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    • 2019
  • The existing middle-long span railway bridge has been mainly applied to steel box girder bridges. However, the steel box girder bridges have disadvantages in securing the space under the bridge, and the main girder is made of a thin plate box shape, resulting in a ringing noise due to the vibration. Many complaints about noise have been raised. For this reason, there is a need for the development of long railway bridges that can replace steel box girder bridges. In this paper, the characteristics of the steel composite railway bridge currently developed were introduced and a time history analysis was conducted using MIDAS Civil reflecting the speed of KTX load for 40m and 50m bridges. In addition, from the analysis results, the dynamic behavior of target bridges were verified and it was examined whether they meet the dynamic performance criteria proposed in the railway design standards. As a result, all of the bridges under review satisfied the dynamic safety criteria, however, in case of 40m of span, the vertical acceleration value was very large. In order to solve this problem, authors proposed the improvement plan and corrected the cross section to confirm that the vertical acceleration decreased.

A Study on the Yield Rate and Risk of Portfolio Combined with Real Estate Indirect Investment Products (부동산간접투자상품이 결합된 포트폴리오의 수익률과 위험에 관한 연구)

  • Choi, Suk-Hyun;Kim, Jong-Jin
    • Journal of Cadastre & Land InformatiX
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    • v.49 no.1
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    • pp.45-63
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    • 2019
  • Until recently, most people have invested in a traditional portfolio consisting of stocks, bonds and real estates based on the three-division method of properties in Korea. However, this study analyzed the impact of the composition of a portfolio combining representative real estate indirect investment products such as Reits and real estate funds on the investment performance. For this purpose, the empirical analysis using the mean variance model, which is the most appropriate method for the portfolio composition, was used. For variables used in this study, mixed asset portfolios were classified into Portfolio A through Portfolio G depending on the composition of assets, and the price indices selected as Kospi, Krx bond, Reits Trus Y7, Hanwha-Lasal fund, and Office (Seoul). The results are as follows; first Portfolio D, which combined bonds, stocks, Reits and Real Estate funds, and Portfolio G, which added the office, the actual real estate, were shown to have the lowest risk. second, Portfolio B composed of bonds, stocks and Reits and Portfolio D with added real estate funds had the lowest risk while Portfolio F composed of bonds, stocks, offices and real estate funds, and Portfolio G with added Reits were the most profitable. As a result, it has been analyzed that it was more effective to compose a portfolio including Reits and real estate funds, which were real estate indirect investment products that eliminated the illiquidity limitation of real estates than real estates, the traditional three-division method of properties. Therefore, it is possible to minimize the risk of investors and reduce the cost of ownership of the real estate by solving the illiquidity problem that is the biggest disadvantage of the direct investment, In addition, it is considered that it is more necessary to reinvigorate the real estate indirect investment market where small amounts can be invested.

Prevalence of Emotional Distress and Related Factors of Orthopedic Surgical Patients in a Military Hospital : A Cross-sectional Feasibility Study (군 병원 정형외과계 입원환자의 정서문제 유병률과 관련 요인)

  • Oh, In Mok;Hong, Minseok;Lee, Soo Yeon;Yoon, Ga Hee;Lee, Ho;Kim, Myung Jin;Kim, Hyun Mi;Lee, Sang Don
    • Anxiety and mood
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    • v.15 no.2
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    • pp.115-121
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    • 2019
  • Objective : The purpose of this study was to investigate prevalence of psychiatric symptoms and determine predictors of emotional distress of military hospital surgical patients. Methods : This study examined 104 orthopedic patients admitted to the Armed Forces Military Hospital September-November 2018. For the study, every subject completed self-assessment inventories regarding depressive and anxiety symptoms (Hospital Anxiety and Depression Scale), sleep problems (Pittsburgh Sleep Quality Index), problematic alcohol and tobacco use (Cut off, Annoyed, Guilty, Eye-opener screening), and psychiatric history. We performed the Student's t-test and the chi-square test for the collected data to investigate the prevalence of psychiatric symptoms, including emotional distress. Logistic regression analysis was used to examine the risk factors related to emotional distress of hospitalized military personnel. Results : There were no significant differences in socio-demographic and psychiatric symptoms between soldiers and officers. The prevalence of depressive and/or anxiety symptoms (emotional distress) was 21.2% (n=21). In the logistic regression analysis, psychiatric history [Adjusted Odds Ratio (AOR)=18.99 ; 95% Confidence Interval (CI)=1.42-253.57 ; p=0.026] and low military life satisfaction (AOR=15.67; 95% CI=1.46-168.11 ; p=0.023) correlated with emotional distress. Conclusion : Soldiers admitted to the military hospital showed similar prevalence of emotional distress as those at general hospitals. Considering military circumstances, it is necessary to detect and intervene regarding soldiers with a psychiatric history and low military life satisfaction to promote mental health at military hospitals.

Direction of Conservation and Management about Cultural Landscape of the Traditional Villages in Huizhou Region, China - Centered on IPA Analysis - (중국 휘주 지역 고촌락 문화경관 보전 관리 방안 - IPA 분석을 중심으로 -)

  • Zhang, Xiao Dong;Park, Jae Chul;Lin, Nan
    • Journal of the Korean Institute of Rural Architecture
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    • v.21 no.3
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    • pp.69-75
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    • 2019
  • The purpose of this study is to provide the conservation management direction about cultural landscape of the traditional villages in the area of Huizhou through the importance-performance analysis. The results of the survey on the importance - performance of 261 people who had many visits to various cultural landscapes of Huizhou villages such as Hongchun, Sidichun etc. are as follows. It was appeared that the item of 'good air' is the highest level of importance and satisfaction and is best condition. The item of 'historical conservation' is the high level of importance, but the level of satisfaction is low, so continuous improvement is necessary. The item of 'Old garden conservation' has high satisfaction but low importance, so it needs to improve its importance through subsequent improvement. The item of 'Keeping of old cemetary and old tower' has low importance and satisfaction but it is above average, so continuous maintenance is needed. The items of 'Preservation of stone gate' and 'Preservation of famous man's birth house' all have slightly higher satisfaction and lower importance. Both items are highly satisfied with their importance, so they should avoid excessive efforts and maintain the present status. Satisfaction with the item of 'water environment and water quality' was the lowest, and the problem of the present condition is the most serious, and a major improvement is needed. The importance and satisfaction of 'Commercial development of old villages' was the lowest among all items. This item is causing serious problems and should provide an overall improvement way to drastically improve the importance and satisfaction. Concentration is necessary to improve the environment of the whole villages, to protect the ecological plants and animals in old villages, to transfer and improve the culture of old villages, to maintain sustainability of the villages, and to protect old temple and old rock in old villages. As the level of satisfaction with sustainability is the lowest in the part of 'Concentrate here', there is a great concern about sustainability. Therefore, it is necessary to focus on sustainability and concentrate on sustainable development.

A Study on Performance of Steel Monocell Expansion Joints (강재형 모노셀 신축이음장치 성능 연구)

  • Kim, Yong-Hoon;Yhim, Sung-Soon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.5
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    • pp.502-509
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    • 2019
  • Studies have been made on performance evaluation of expansion joint systems for an ordinary highway or road bridge. However little study has been made for runway connection bridges at airports. A study on performance evaluated from computer code analysis and shrinkage, extension, and compression repetition tests based on KS F 4425 is conducted to a newly developed expansion joint system which has been installed in a runway connection bridge at Incheon Airport Extension 2 Construction Site. The MIDAS computer code is used to analyze the performance before the manufacture of the mock-up of expansion joint system on the basis of design requirements. Tests based on the KS F 4425 of 2001 year-version are conducted for the mock-up. Domestic codes and standards to validate the performance of the expansion joint system in a connection bridge have been developed for a vehicle. However the expansion joint system tested in this study is installed in a runway connection bridge for an aircraft. Conservatively the heaviest one among airplanes departing and landing at Incheon Airport is assumed level-F $468.4kN/m^2$ and adopted for the tests and analyses in this study. KS F 4425 method is selected for the shrinkage, extension, and compression repetition tests. No remarkable problem was observed for the 2,500-cycle shrinkage and extension and two million-cycle repeatition load tests. The results of this study are expected to contribute to establishment of code and standard for the performance validation of an expansion joint system installed in a runway connection bridge for an aircraft by providing performance test results and computer analysis results based on finite element methods.

Study for Flow Phenomenon in the Circulation Water Pump Chamber using the Flow-3D Model (Flow-3D 모형을 이용한 순환수취수펌프장 내 흐름현상 연구)

  • Ha, Sung-Won;Kim, Tae-Won;Choi, Joo-Hwan;Park, Young-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.4
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    • pp.580-589
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    • 2019
  • Indonesia has a very short supply of electricity. As a solution to this problem, plans for construction of thermal power plants are increasing. Thermal power plant require the cooling water system to cool the overheated engine and equipment that accompany power generation, and the circulation water pump chamber among the cooling water system are generally designed according to the ANSI (1998) standard. In this study, the design criterion $20^{\circ}$ for the spreading angle of the ANSI (1998) of the layout of the circulating water pump chamber can not be satisfied on the K-coal thermal power plant site condition in Indonesia. Therefore, 3-D numerical model experiment was carried out to obtain a hydraulically stable flow and stable structure. The Flow-3D model was used as numerical model. In order to examine the applicability of the Flow-3D model, the flow study results around the rectangular structure of Rodi (1997) and the numerical analysis results were compared around the rectangular structures. The longitudinal velocity distribution derived from numerical analysis show good agreement. In order to satisfy the design velocity in the circulating water pump chamber, a rectangular baffle favoring velocity reduction was applied. When the approach velocity into the circulating water pump chamber was occurred 1.5 m/s ~ 2.5 m/s, the angle of the separation flow on the baffle was occurred about $15^{\circ}{\sim}20^{\circ}$. By placing the baffle below the separation flow angle downstream, the design velocity of less than 0.5 m/s was satisfied at inlet bay.

A Study on the Functional Analysis of Parking Lot Expansion Technology using Technology-Tree (기술트리를 이용한 주차장 확대 기술의 기능분석에 관한 연구)

  • Youn, Bohyung;Choi, Jaewook;Park, Sungpyo;Kim, Taewan;Lee, Chansik
    • Korean Journal of Construction Engineering and Management
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    • v.20 no.3
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    • pp.64-76
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    • 2019
  • Aged apartments lack parking space and are suffering from severe parking difficulties due to the increase in the supply of private cars due to the economic improvement. Efficient remodeling technology is required as a way to solve the problem of a shortage of parking spaces, but there is a lack of establishing a technology for remodeling plans that can reflect the characteristics of various parks. This study was conducted to analyze the functions of the parking lot expansion technology using the technology tree and to derive the final technology through the function deployment. As a result of functional deployment of the plan to expand the parking lot, the fifth function was deployed and a total of 22 technologies were derived. Four types of technologies are categorized, four technologies for underground expansion, 12 technologies for underground and ground expansion, two technologies for ground expansion, and four technologies for ground-based expansion. As a result of the functional deployment of the main entrance plan, the fifth function was deployed and derived with 22 technologies. The total technologies were grouped into four categories, four technologies for direct underground entry, 11 technologies for indirect underground entry, three technologies for direct access to ground, and four technologies for indirect entry to ground. Through case verification, the detailed technologies applied to the semi-industrial complex of remodeling were identified and expert surveys and interviews were conducted to verify the adequacy of the technology tree.

Measurement of ground behaviour due to tunnelling using No-target program in laboratory model test (실내모형시험에서 No-target 프로그램을 이용한 터널 굴착으로 인한 지반거동 측정)

  • Lee, Jong-Hyun;Lee, Chang-No;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.3
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    • pp.397-418
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    • 2019
  • It is very important to understand and analyze the interactive behaviour between ground and adjacent structures due to tunneling. With many technological advancement in modern society, numerous methods for analyzing the interactive behaviour are used in a wide range of civil engineering fields. Close range photogrammetry is mainly being used in the field of geotechnical engineering and research on measuring methods associated with GeoPIV has been currently increased. Originally, the close range photogrammetry using target points and aluminum rods for VMS (Vision Measurement System) program has been used. However, applying this has a problem that external errors can be occurred because the target points are artificially installed by hand, and if the grid between points is being wider or narrower, deficient data can be obtained. Therefore, in this study, MATLAB-based No-target program that can analyze displacement without using target was developed. Additionally, this study focused on comparison and verification with existing program through numerical analysis and laboratory model test. Three cases of Greenfield condition, Strip foundation, and Pile foundation were analyzed. From results of VMS program and No-target program, the error rate and reliability of the total displacement and the vertical displacement were analyzed. It was also compared and verified through the finite element numerical program, PLAXIS.