• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.12
• /
• pp.889-898
• /
• 2022

In this paper, parallel computing method on the three-dimensional electromagnetic field is proposed. The present electromagnetic scattering analysis is conducted based on the time-harmonic vector wave equation and the finite element method. The edge-based element and 2^nd -order absorbing boundary condition are used. Parallelization of the elemental numerical integration and the matrix assemblage is accomplished by allocating the partitioned finite element subdomain for each processor. The graph partitioning library, METIS, is employed for the subdomain generation. The large sparse matrix computation is conducted by MUMPS, which is the parallel computing library based on the multi-frontal method. The accuracy of the present program is validated by the comparison against the Mie-series analytical solution and the results by ANSYS HFSS. In addition, the scalability is verified by measuring the speed-up in terms of the number of processors used. The present electromagnetic scattering analysis is performed for a perfect electric conductor sphere, isotropic/anisotropic dielectric sphere, and the missile configuration. The algorithm of the present program will be applied to the finite element and tearing method, aiming for the further extended parallel computing performance.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.6
• /
• pp.115-131
• /
• 2022

Carbon dioxide (CO₂) emissions from the transportation sector in South Korea accounts for 16.5% of all CO₂ emissions, and road transportation accounts for 96.5% of this sector's emissions in South Korea. Hence, constant research is being carried out on methods to reduce CO₂ emissions from this sector. With the emerging use of smart crossings, attempts to monitor individual vehicles are increasing. Moreover, the potential commercial deployment of autonomous vehicles increases the possibility of obtaining individual vehicle data. As such, CO₂ emission research was conducted at five signalized intersections in the Gangnam District, Seoul, using data such as vehicle type, speed, acceleration, etc., obtained from image detectors located at each intersection. The collected data were then applied to the MOtor Vehicle Emission Simulator (MOVES)-Matrix model-which was developed to obtain second-by-second vehicle activity data and analyze daily CO₂ emissions from the studied intersections. After analyzing two large and three small intersections, the results indicated that 3.1 metric tons of CO₂ were emitted per day at each intersection. This study reveals a new possibility of analyzing CO₂ emissions using actual individual vehicle data using an improved analysis model. This study also emphasizes the importance of more accurate CO₂ emission analyses.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.25 no.2
• /
• pp.101-120
• /
• 2023

Electrical resistivity survey have been widely conducted at diverse scales, from a few centimeters for laboratory tests to kilometers for field tests. It measures electrical resistance through relationship of electric potential difference and current between two electrodes penetrated on the surface of medium, and eventually quantifies electrical resistivity known as inherent properties of the medium. In field or full-scale test, it assumes the electrodes as equivalent half-sphere electrodes that have a same surface area with different electrodes for ease of calculation because the contact area between electrode and medium is small and sufficient distance between two electrodes. However, small-scale laboratory test is significantly affected by the electrode geometries (penetrated depth, height, radius of electrode and distance between electrodes), which change the equipotential surface and electric current flow. Indeed, the electrode geometries may eventually cause a difference of electrical resistivity value. This study reviews the theoretical electrical resistance derived with various electrode geometries (half-sphere, cylinder, cylindrical with half-spherical tip, cylindrical with conical tip) and verifies the developed numerical module by comparing results with the theoretical electrical resistance. The distributions of electrical resistance around electrodes and among electrodes are analyzed. In addition, it is discussed how the electrical characteristic of cylindrical electrode with conical tip widely used in field test has effect on the electric current flow.

• The Journal of Engineering Geology
• /
• v.33 no.2
• /
• pp.307-322
• /
• 2023

Rock-mass grouting plays a crucial role in the construction of dams and deep caverns, effectively preventing seepage in the foundations, enhancing stability, and mitigating hazards. Most rock grouting is affected by hydrogeological and rock engineering indices such as rock quality designation (RQD), rock mass quality (Q-value), geological strength index (GSI), joint spacing (Js), joint aperture (Ap), lugeon value (Lu), secondary permeability index (SPI), and coefficient of permeability (K). Therefore, accurate geological analysis of basic rock properties and guidelines for grouting construction are essential for ensuring safe and effective grouting design and construction. Such analysis has been applied in dam construction sites, with a particular focus on the geological characteristics of bedrock and the development of prediction methods for grout take. In South Korea, many studies have focused on grout injection materials and construction management techniques. However, there is a notable lack of research on the analysis of hydrogeological and rock engineering information for rock masses, which are essential for the development of appropriate rock grouting plans. This paper reviews the current state of research into the correlation between the grout take with important hydrogeological and rock engineering indices. Based on these findings, future directions for the development of rock grouting research in South Korea are discussed.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.3
• /
• pp.88-103
• /
• 2023

With the recent advancement of 4th Industrial Revolution technology, transportation systems are generating large amounts of mobility data related to the individual movement trajectories of vehicles and people. There are many constraints on utilizing mobility data containing personal information. Thus, in South Korea, the processing and generation of pseudonymized information and the analysis and utilization of this information have been managed in a dual manner by applying separate agencies and technologies through the revision of the Data 3 Act and the enactment of the Data Basic Act. However, this dual approach fails to securely support the entire data lifecycle and suffers from inefficiencies in terms of processing time and cost. Therefore, to compensate for the problems of the existing Expert Data Combination System and Data Safety Zone, this study proposes an Integrated Data Safety Zone Framework that integrates and unifies the process of generating, processing, analyzing, and utilizing mobility data. The integrated process for data processing was redesigned, and common requirements and core technologies were derived. The result is an architecture for a next-generation Integrated Data Safety Zone system that can manage and utilize the entire life cycle of mobility data at one stop.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6A
• /
• pp.835-842
• /
• 2008

The response surface method (RSM) is widely adopted for the structural reliability analysis because of its numerical efficiency. However, the RSM is still time consuming for large-scale applications and sometimes shows large errors in the calculation of sensitivity of reliability index with respect to random variables. Therefore, this study proposes a new RSM in which moving least squares (MLS) approximation is applied. Least squares approximation generally used in the common RSM gives equal weight to the coefficients of the response surface function (RSF). On the other hand, The MLS approximation gives higher weight to the experimental points closer to the design point, which yields the RSF more similar to the limit state at the design point. In the procedure of the proposed method, a linear RSF is constructed initially and then a quadratic RSF is formed using the axial experimental points selected from the reduced region where the design point is likely to exist. The RSF is updated successively by adding one more experimental point to the previously sampled experimental points. In order to demonstrate the effectiveness of the proposed method, mathematical problems and ten-bar truss are considered as numerical examples. As a result, the proposed method shows better accuracy and computational efficiency than the common RSM.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.5
• /
• pp.30-39
• /
• 2023

Large dams, which are critical infrastructures for disaster prevention, are exposed to various risks such as aging, floods, and earthquakes. Better dam safety inspection and diagnosis using digital transformation technologies are needed. Traditional visual inspection methods by human inspectors have several limitations, including many inaccessible areas, danger of working at heights, and know-how based subjective inspections. In this study, drone photogrammetry was performed on two large dams to evaluate the applicability of digital data-based dam safety inspection and propose a data management methodology for continuous use. High-quality 3D digital models with GSD (ground sampling distance) within 2.5 cm/pixel were generated by flat double grid missions and manual photography methods, despite reservoir water surface and electromagnetic interferences, and severe altitude differences ranging from 42 m to 99.9 m of dam heights. Geometry profiles of the as-built conditions were easily extracted from the generated 3D mesh models, orthomosaic images, and digital surface models. The effectiveness of monitoring dam deformation by photogrammetry was confirmed. Cracks and deterioration of dam concrete structures, such as spillways and intake towers, were detected and visualized efficiently using the digital 3D models. This can be used for safe inspection of inaccessible areas and avoiding risky tasks at heights. Furthermore, a methodology for mapping the inspection result onto the 3D digital model and structuring a relational database for managing deterioration information history was proposed. As a result of measuring the labor and time required for safety inspection at the SYG Dam spillway, the drone photogrammetry method was found to have a 48% productivity improvement effect compared to the conventional manpower visual inspection method. The drone photogrammetry-based dam safety inspection is considered very effective in improving work productivity and data reliability.

• Journal of Biosystems Engineering
• /
• v.6 no.2
• /
• pp.20-32
• /
• 1982

This survey was conducted to investigate the present status of farm tractor utilization for obtaining a basic reference to the establishment of the government's agricultural mechanization strategies. Thirty two counties from the eight provinces except Jeju were covered in this study. From these selected areas, 433 sample farms having farm tractor were taken to obtain the general informations by the enquete, and 93 sample farms among them to investigate the status of daily tractor use in the year of 1980. The analyzed results are summarized as follows: 1. Farm tractors owned by the rice-oriented farms holds 71.5 percent of the total number of tractors the livestock-oriented farms 17.0 percent, and the orchard-oriented farms 7.0 percent. Among the farm tractors 64.3 percent was a large size (46ps) and 35.7 percent a small size(19~23ps). 2. Most of the tractors surveyed were equipped with the essential attachments such as plow and rotavator. About 18 percent of the tractor owners had no trailer, which seemed too high considering the large percentage of tractor use for transportation. The availability of other attachments was very low except a grader on the rice-oriented farms and a hay harvester and a front loader on the livestock-oriented farms. 3. The average size of farm was 3.9 hectare for the rice-oriented farms, 13.9 hectare for the livestock-oriented farms and 7.4 hectare for the orchard-oriented farms. It was obious that the average farm size of was too small compared to the theoretical machine capacity of the tractors. 4. About 70 percent of the tractor operators were in the age of twenties and thirties. About 90 percent of them had an educational level of middle school graduate or above even though their technical level was very low. 5. Any particular problem in tractor use was not found in this survey. From the farmer's preference for purchasing a new tractor, however, it is estimated the demand on a 20-30ps tractor will be more increased. 6. The average annual use of tractor was of about 100 days or 400 hours. It appeared that the rice-oriented farms used most with 412.4 hours per year, and followed by the livestock-oriented farms with 403.6 hours, the orchard oriented farms with 377.7 hours. 7. Among the total hours of tractor use, 47.3 percent was for transportation, and 41.6 percent was for plowing and rotary tillage. The largest portion of the annual tractor use was taken by transportation on the livestock-oriented farms, by land preperation on the rice-oriented farms, and by loading and chemical spraying on the orchard-oriented farms. 8. The hours of tractor use had a peak in May. The hours of use for own farm was remarkably different among the different farm oriented, but there was no considerable difference between the too different sizes of tractor. 9. The hours of tractor use decreased as the age of the operator or the educational level increased. The reason might be that the operators who had a high educational level or were older had a tendency of disliking custom works. 10. The average custom use of tractor was 171.3 hours per year, and the ratio of custom work was 63.7 percent on the rice-oriented farms, 31.7 percent on the livestock-oriented farms and 22.4 percent on the orchard-oriented farms. Among the custom works, the most popular one was the grader leveling. 11. The charge on custom work was about 40,000 Won per hectare for plowing and rotary tillage, and it was the most expensive in the southeastern region, and next followed by the southwestern region. 12. The average plowing capacity of the small tractor was 7.8 hours per hectare in the paddy field, and that of the large tractors was 4.3 hours per hectare. The average rotary-tilling capacities of the small and the large tractors were 6.5 and 4.3 hours per hectare, in the paddy field respectively.

• Korean Journal of Environment and Ecology
• /
• v.30 no.6
• /
• pp.986-995
• /
• 2016

The objective of this study was to analyze the distribution of endangered fish species and elucidate their relations on chemical water quality, physical habitat conditions and ecological stream health. The dominant species in the watershed was Pseudopungtungia nigra (Pn), Gobiobotia macrocephala (Gm), Gobiobotia brevibarba (Gb), Liobagrus obesus (Lo), and Iksookimia choii (Ic) in the order. The species of Pn designated as "critical endangered species (I) (CER)", was most widely distributed species among the endangered species, so the designation of the species should be re-evaluated. The endangered species was most popular (4 species, 384 individuals) in the Cho-River region of eighteen lotic regions. According to the analysis of chemical tolerance limits in the habitats with endangered fish species, biological oxygen demand (BOD) and total phosphorus (TP) was analyzed as "very good" (Ia) and "good condition" in the chemical criteria of the Ministry of Environment, Korea. Also, chemical conditions, based on ammonia-N ($NH_{4+}$), total nitrogen (TN), phosphate-P ($PO_{4^-}P$) were much better in the habitat with endangered species (Hw) than the habitat without endangered species (Ho). In the meantime, the species of Ic showed wide ranges on the chemical tolerance, so physical habitat conditions, such as the size of substrate particles (sand) and hydrological regime, were considered as more important factors than the chemical water quality, if the water quality is not largely degraded. The endangered species were also more distributed in the high-order (4-6) streams than the low-order (1-3) streams. The evaluation of ecological stream health, based on multi-metric model of the Index of Biological Integrity (IBI), showed the large difference between the Hw (21.6, fair condition)and Ho (30.5, good condition), indicating that the habitat maintained well chemically and physically had higher distributions of endangered species. Overall, the designation of CER on the Pn should be re-evaluated due to wide-distributions, and the protections from water pollution and the habitat conservations on the endangered species are necessary in the watershed.

• Research in Community and Public Health Nursing
• /
• v.11 no.1
• /
• pp.289-316
• /
• 2000

우리나라의 경우 지역사회 재난 관리계획과 훈련이 보건의료적 모형이라기 보다는 민방위 모형에 입각하기 때문에 사고 현장에서의 환자 중증도 분류, 합리적 환자배분 및 이송, 병원 응급실에서의 대처 등이 체계적으로 이루어지지 못하고 있으며, 지역사회가 이에 즉각적으로 반응할 수 없다. 본 연구는 삼풍 붕괴사고 시에 대응방식과 그 후의 우리나라 응급의료 체계를 분석함으로써 대형사고 예방과 재난관리를 위한 우리나라 응급의료체계의 개선방안과 간호교육에서의 준비부분을 제시하고자 한다. 1 삼풍 사고 발생시에는 이를 관장할 만한 법적 근거인 인위적 재해에 관한 재난관리법이 없었다. 따라서 현장에서는 의학적 명령체계를 확보하지 못했기 때문에 현장에서의 응급 처치는 전혀 이루어지지 못하였다. 현장에서의 중증도 분류. 응급조치와 의뢰, 병원과 현장본부 그리고 구급차간의 통신 체계 두절, 환자 운송 중 의료지시를 받을 수 있도록 인력, 장비, 통신 체계가 준비되지 못하였던 점이 주요한 문제였다. 또한 병원 응급실에서는 재난 계획이 없거나 있었더라도 이를 활성화하여 병원의 운영 체계를 변환해가지 못하였다. 2. 삼풍백화점 붕괴사고 한달 후에는 인위적 재해에 대한 재난관리법이 제정되고, 행정부 수준별로 매년 지역요구에 합당한 재난관리 계획을 세우도록 법으로 규정하였다. 재난 관리법에는 보건의료 측면에서의 현장대응, 주민 참여, 응급 의료적 대처, 정보의 배된. 교육/훈련 등이 포함되어 있어야 한다. 그러나 법적 기반이 마련된 이후에도 한국 재난 계획 내에는 응급의료 측면의 대응 영역은 부처간 역할의 명시가 미흡하며, 현장에서의 응급 대응과정을 수행할 수 있는 운영 지침이 없이 명목상 언급으로 그치고 있기 때문에 계획을 활성화시켜 지역사회에서 운영하기는 어렵다. 즉 이 내용 속에는 사고의 확인 /공고, 응급 사고 지령, 요구 평가, 사상자의 중증도 분류와 안정화, 사상자 수집, 현장 처치 생명보존과 내과 외과적 응급처치가 수반된 이송, 사고 후 정신적 스트레스 관리, 사고의 총괄적 평가 부분에 대한 인력간 부처간 역할과 업무가 분명히 제시되어 있지 못하여, 사고 발생시 가장 중요한 연계적 업무 처리나 부문간 협조를 하기 어렵다. 의료 기관과 응급실/중환자실, 시민 안전을 책임지고 있는 기관들과의 상호 협력의 연계는 부족하다. 즉 현재의 재난 대비 계획 속에는 부처별 분명한 업무 분장, 재난 상황에 따른 시나리오적 대비 계획과 이를 훈련할 틀을 확보하고 있지 못하다. 3. 지방 정부 수준의 재난 계획서에는 재난 발생시 보건의료에 관한 사항 전반을 공공 보건소가 핵심적 역할을 하며 재난 관리에 대처해야 된다고 규정하고 있다. 그러므로 보건소는 지역사회 중심의 재난 관리 계획을 구성하고 이를 운영하며, 재난 현장에서의 응급 치료 대응 과정은 구조/ 구명을 책임지고 있는 공공기관인 소방서와 지역의 응급의료병원에게 위임한다. 즉 지역사회 재난 관리 계획이 보건소 주도하에 관내 병원과 관련기관(소방서. 경찰서)이 협동하여 만들고 업무를 명확히 분담하여 연계방안을 만든다. 이는 재난관리 대처에 성공여부를 결정하는 주요 요인이다. 4 대한 적십자사의 지역사회 주민에 대한 교육 프로그램은 연중 열리고 있다. 그러나 대부분의 교육주제는 건강증진 영역이며. 응급의료 관리는 전체 교육시간의 8%를 차지하며 이중 재난 준비를 위한 주민 교육 프로그램은 없다. 또한 특정 연령층이 모여있는 학교의 경우도 정규 보건교육 시간이 없기 때문에 생명구조나 응급처치를 체계적으로 배우고 연습할 기회가 없으면서 국민의 재난 준비의 기반확대가 되고 있지 못하다. 5. 병원은 재난 관리 위원회를 군성하여 병원의 진료권역 내에 있는 여러 자원을 감안한 포괄적인 재난관리계획을 세우고, 지역사회를 포함한 훈련을 해야 한다. 그러나 현재 병원은 명목상의 재난 관리 계획을 갖고 있을 뿐이다. 6. 재난관리 준비도를 평가할 때 병원응급실 치료 팀의 인력과 장비 등은 비교적 기준을 충족시키고 있었으나 병원의 재난 관리 계획은 전혀 훈련되고 있지 못하였다 그러므로 우리나라 재난 관리의 준비를 위해서는 현장의 응급의료체계, 재난 대응 계획, 이의 훈련을 통한 주민교육이 선행되어야만 개선될 수 있다. 즉 민방위 훈련 모델이 아닌 응급의료 서비스 모델에 입각한 장기적 노력과 재원의 투입이 필요하며, 지역사회를 중심으로 대응 준비와 이의 활성화 전략 개발, 훈련과 연습. 교육에 노력을 부여해야 한다. 7. 현장의 1차 응급처치자에 대해서는 법적으로 명시하고 있는 역할이 없다. 한국에서는 응급구조사 1급과 2급에 대한 교육과 규정을 1995년 이후 응급의료에 관한 법률에서 정하고 있다. 이 교육과정은 미국이 정하고 있는 응급구조사 과정 기준과 유사하지만 실습실이나 현장에서의 실습시간이 절대적으로 부족하다. 덧붙여 승인된 응급구조사 교육 기관의 강사는 강사로서의 자격기준을 충족할 뿐 아니라 실습강사는 대체적으로 1주일의 1/2은 응급 구조차를 탑승하여 현장 활동을 끊임없이 하고 있으며, 실습은 시나리오 유형으로 진행된다. 그러므로 우리나라의 경우 응급 구조사가 현장 기술 인력으로 역할 할 수 있도록 교과과정 내에서 실습을 강화 시켜야하며, 졸업생은 인턴쉽을 통한 현장 능력을 배양시키는 것이 필요하다. 8. 간호사의 경우 응급전문간호사의 자격을 부여받게 됨에 따라, 이를 위한 표준 교육 지침을 개발함으로써 병원 전 처치와 재난시 대응할 수 있는 역량을 보완해야 한다. 또한 현 자격 부여 프로그램 내용을 고려하여 정규자격 간호사가 현장 1차 치료자(first responder)로 역할 할 수 있도록 간호학 교과과정을 부분 보완해야한다.