• Journal of Digital Convergence
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• v.20 no.5
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• pp.643-651
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• 2022

This study was conducted to examine the oral health, dental treatment and insurance awareness of the community during the COVID-19 period from September 1 to October 29, 2021 for patients who visited a local dental clinic in Gangwon-do. For analysis, SPSS Statistics 24.0 program was used. As a result of the analysis, it was found that oral health status, interest in oral health, and awareness of health insurance expansion affect dental treatment during the COVID-19 period. In addition, those who did not receive oral health education, those with a high school diploma or lower, and those with poor oral health showed positive results for dental treatment during the COVID-19. In conclusion, it is necessary to expand publicity on oral health education, and to list the cost of infection control in health insurance and separate compensation materials. In future research, I think that it is necessary to conduct research through a variety of subjects and study the expansion of insurance in detail.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.59-70
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• 2010

A long-term field demonstration experiment on selected stabilization methods to reduce the heavy metal mobility in farmland soil contaminated by heavy metals was conducted. The field demonstration experiment was established on the contaminated farmland with wooden plates (thickness = 1 cm), of which the dimension were width = 200 cm, Length = 200 cm, height = 80 cm, filled with treated soil, which was mixed with lime stone and steel refining slag except on control plot. Soil samples in the plots were collected and analyzed during the experiment period (6 months) after the installation of the plots. The field demonstration experiment results showed that the application lime stone at the ratio of 5% was effective for immobilizing heavy metal components in contaminated farmland soil.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.249-249
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• 2021

도시지역의 우수유출해석 모형인 SWMM 모형의 매개변수는 유역유출관련 매개변수와 우수관로 매개변수로 구분이 된다. 이중 우수관로내 수리거동에 영향을 대표적인 매개변수는 조도계수가 있다. 우수관로 조도계수는 우수관로의 규격 및 재료에 따라 적용범위가 제시되어 있지만 현상태 관로내 퇴적 및 협잡물 등에 의한 조도변화가 발생하게 된다. 따라서 본 연구에서는 우수관로 조도계수의 변화에 따른 유량의 민감도를 검토하고 모니터링 유량과 비교를 통한 연구 대상지역의 최적 조도계수를 선정하였다. 연구 대상지역은 울산광역시 삼호동 일대이며 대상지역 내 발생한 우수유출은 최종적으로 태화강으로 방류되는 구조를 갖고 있는 배수분구이다. 조도계수 민감도 분석에 적용한 조도계수의 범위는 일반적인 원형 우수관로의 조도계수 0.013을 기준으로 하고 0.002씩 증감을 시켜 총 6개 CASE에 대한 민감도 분석을 수행하였다. 모의 유량의 비교군이 되는 관측 유량의 경우는 초음파 유량계로 관측한 총 3개 지점의 유량자료를 이용하여 민감도 분석에 활용하였다. 조도계수 민감도 분석결과 조도계수 증가에 따라 첨두유량은 감소하게 된다. 각 지점별 첨두유량 변화 폭은 지점 4, 5, 6에 각각 7.0% (-3.4~3.6%), 14.3% (-7.5~6.8%), 15.6% (-7.7~7.9%) 증감 폭을 갖는 것으로 분석되었으며, 유역의 하류부로 갈수록 변동 폭이 커지는 것으로 분석되었다. 시계열 수문곡선 비교결과 지점 4에서는 조도계수 0.011, 지점 5는 0.013, 지점 7은 0.015를 적용하는 것이 실측치와의 상관계수가 가장 높게 나타나는 것으로 분석되었다. 이상의 분석 결과를 토대로 유역의 관 흐름 상태의 변화는 관로의 퇴적, 부유물, 폐유부착 등의 유지관리 상태에 따라 달라지며 특히 유역의 하류부로 갈수록 퇴적, 부유물 등의 축척이 누적되어 조도계수를 상류부 보다 기준 값보다 크게 적용해야 관측치 유량과 유사하게 모의되는 것을 확인하였다. 따라서 도시유출해석 모형에서의 조도계수 적용은 우수관로의 유지관리 상태 등을 고려하여 우수관로별 적용 값 다르게 입력하는 것이 타당한 것으로 판단된다.

• Korean Journal of Construction Engineering and Management
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• v.24 no.4
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• pp.25-34
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• 2023

The purpose of this study is to calculate and compare construction costs for On-Site Construction and Off-Site Construction in Plant Project. For this purpose, the target for calculating the construction cost was limited to the Pipe Rack(Steel Structure and Piping). The results derived according to the purpose of the study are as follows. 1)The direct construction cost for On-Site Pipe Rack construction was KRW 56 billion, with Steel Structure KRW 25.1 billion and Piping KRW 30.8 billion won. 2)Comparing the rate of change between On-Site Construction and Off-Site Construction, material costs increased by 1.9% and expenses by 192.1%, but labor costs decreased by -9.1%, resulting in a total direct construction cost increase of 8.4%. These results can be used as reference data to check the current status of the increase or decrease in construction costs when constructing Pipe Racks as Off-Site Construction.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.467-467
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• 2022

1990년대 후반부터 시작된 자연형 하천정비 사업은 기존의 수질보전정책 외에도 하천생태계에 대한 관심이 부각되는 계기로 작용하고 있다. 이 중 환경생태유량은 기존의 하천유지유량보다 확대된 개념으로 수생태계 건강성 회복을 위한 중요한 요소이다. 본 연구에서는 도시하천 수생태계 건강성 회복방안 마련을 위한 기초자료 마련을 위해 부산의 대표적인 도시하천인 온천천과 학장천을 대상으로 환경생태유량을 산정하였다. 환경생태유량은 하천의 물리적 특성 및 어류·유량을 조사하는 하천현장조사, 서식지적합도지수 산정의 과정을 통해 산정된다. 온천천과 학장천에서 각각 3개의 대표지점을 선정하고 각 지점별로 2회의 현장조사를 통해 각 지점에서의 수심, 유속, 하상재료, 어류 조성을 조사하였다. 조사결과를 바탕으로 붕어와 참갈겨니를 대표어종으로 선정하고 Instream Flow and Aquatic Systems Group(IFASG, 1986)에서 제시한 방법을 이용하여 서식지적합도지수를 산정한 후, 미국지질조사국의 물리적서식지모의시스템(PHABSIM)을 이용하여 하천별, 어종별 환경생태유량을 산정하였다. 온천천의 경우, 붕어와 참갈겨니 모두 약 0.7~0.8m³/s에서 가용서식지면적이 가장 크게 산정되어 일 60,000~70,000m³ 가량의 환경생태유량 공급이 필요한 것으로 나타났다. 학장천의 경우, 붕어는 약 0.6~0.7m³/s, 참갈겨니는 약 0.3~0.4m³/s에서 가용서식지면적이 가장 크게 산정되어, 각각 일 50,000~60,000m³, 25,000~35,000m³ 가량의 환경생태유량이 필요한 것으로 나타났다. 본 연구로부터 산정된 환경생태유량을 금번 관측유량 및 현재의 하천유지용수 공급계획량과 비교해보면 온천천에서는 일 15,000m³ 이상, 학장천에서는 어종에 따라 일 7,000m³ 이상의 추가유량 확보가 필요한 것을 알 수 있었다. 특히 학장천의 경우, 어종에 따른 환경생태유량의 차이가 크게 나타나 하천 구간별 유량조사를 통해 어종별 주요 서식지 구간 설정 및 관리가 필요할 것으로 판단된다.

• Journal of the Korea Institute of Building Construction
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• v.23 no.6
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• pp.673-682
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• 2023

This study investigates the delay in setting characteristics of mortar influenced by variations in super retarding agent(SRA) content, curing temperature, and strength levels. Utilizing a settimeter, the research introduces an objective approach to accurately determine the setting time of concrete with SRA under diverse environmental and material mixing conditions at construction sites. The findings indicate that the settimeter, in conjunction with a nonlinear regression model, can effectively estimate the setting time of super retarding mortar. Optimal management of the initial setting is recommended at approximately 45ST and the final setting around 80ST. This methodology enables more effective quality control in the setting times of super retarding concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.17-26
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• 2024

In recent times, accidents involving structural elements, formwork, and shore have been persistently occurring during concrete pouring, especially in multi-story reinforced concrete (RC) structures. In previous studies, research on construction load analysis was mainly conducted for cases where the thickness of all slabs is constant. However, when the thickness of some slabs is different, the variation in the stiffness of slab cross-sections can lead to different distributions of construction loads, necessitating further investigation. In this study, the slab thickness was set as a variable, and the analysis of the distribution of construction loads was conducted, taking into account the influence of changes in slab thickness on the concrete stiffness and structure. It was confirmed that not only the concrete material stiffness but also the slab cross-section stiffness should be considered in the estimation of construction loads when the slab thickness changes. As the slab thickness increases, the maximum construction load and maximum damage parameter on the layer with increased thickness significantly increase, and it was observed that a thicker slab results in a higher proportion of construction load.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.77-86
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• 2024

In this study, authors attempted to determine the bond behavior characteristics to utilize Grid typed CFRP reinforcement as an alternative to steel rebar used as concrete reinforcement. Since it is difficult to understand the influence of the transverse grid length of the Grid typed CFRP reinforcement in the existing numerical analysis proposal for bond behavior, a nonlinear 3D model was created and finite element analysis was performed. To perform the analysis, the analysis was conducted by inputting a nonlinear material model and modeling the bond interface characteristics between the Grid typed CFRP reinforcement and concrete and comparing them with the actual direct pull-out test results. The bond behavior characteristics of the Grid typed CFRP reinforcement were found to be very dominated by the factors of the transverse grid, and showed a tendency to continuously increase load.

• Journal of the Korea Institute of Building Construction
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• v.24 no.1
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• pp.77-86
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• 2024

In this study, an evaluation was conducted for a total of 16 conditions to suggest an appropriate construction method for the construction joint of polyurea waterproofing membrane coating. It was analyzed that the longer the construction time difference, the higher the rate of water leaks through joints, and it was confirmed that water leaks could be prevented through primer construction. In addition, since the surface of polyurea exposed outdoors for a long period of time is deteriorated and weakened, it was analyzed that polishing the area increases surface damage and affects the formation of the interface. During maintenance construction, it would be desirable to apply a primer before construction, and it is believed that using the same urea-based material will ensure waterproofing stability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.4
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• pp.48-54
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• 2024

NPP (Nuclear power plant) structures have been constructed near to the sea shore line for cooling water and exposed to steel corrosion due to chloride attack. Regarding NPP structures built in the UAE, chloride transport may be more rapid than those in the other regions since the temperature near to the coast is high. In this study, concrete samples with 5,000psi (35MPa) design strength grade were manufactured with the materials and mix proportions, which were the same as used in the UAE NPP structures, then chloride diffusion coefficients were evaluated considering temperature and curing age. The compressive strength and the diffusion coefficient were evaluated and analyzed for the samples with 28 and 91 curing days. In addition, chloride diffusion tests for 91-day-cured condition were carried out in the range of 20℃ to 50℃. The activation energy was obtained through converting the temperature slope to a logarithmic function and it was compared with the previous studies. The proposed activation energy can be useful for a reasonable durability design by using actual temperature-dependent chloride diffusion coefficient.