• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.223-223
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• 2020

하천 조사에 드론의 필요성은 점차 증가하고 있으며, 하천시설 조사 및 하천 물리량 간접 계측 등에 있어서 활용성 또한 증가하고 있다. 드론을 이용한 하천시설 및 하천 조사는 주로 광학 영상에 기초한 간접 계측을 중심으로 활발히 기술 개발이 진행되고 있으며, 최근에는 적용하는 임무장비를 확장하여 초분광카메리나 LiDAR 등을 활용하려는 시도가 활발히 이루어지고 있으며, 관련 기술의 개발도 역시 급격히 진행되고 있다. 이러한 기술 발전을 통해 하천 조사에 있어서 간접 계측의 정확도는 계속하여 증가하고 있으나, 기술의 편리성이나 활용성에 비해 정확도 향상에는 어느 정도 한계가 있으며, 간접 계측에 의한 정확도를 확보하기 위해서는 여전히 직접 계측 결과와 비교를 통한 검보정이 필수적이다. 직접 계측은 첨단 계측기를 사용한다고 하더라도 아직까지 인력에 의한 의존도가 높으며, 측정 효율이 여전히 떨어지고 있어 간접 계측의 편리성을 저하시키는 원인으로 작용하고 있다. 본 연구에서는 드론 기반의 간접 계측이 편리성 및 활용성, 정확도를 올리 수 있는 무인 IoT 수질 측정기를 개발하고자 한다. 무인 IoT 수질 측정기는 드론에서 측정한 자료 검보정 자료 획득을 목표로 하며, 드론으로 측정한 지역에 대한 데이터 검보정 정확도를 향상 시킬 수 있는 측정방안을 고려하고 있으며, 현재 이용 가능한 IoT 통신 모듈의 적용성 및 통신 거리를 고려하여 개발을 진행하고 있다. 특히 데이터 전송을 고려하여 개별 통신 규약 검토를 진행하였으며, 각종 표준을 검토하였다. 통신을 위한 전력 소모를 고려하여 저전력 통신 모듈을 중심으로 검토를 진행하였으며, 하천의 특성을 고려한 수질 측정 지점 결정을 위한 측정 알고리즘을 개발하여 적용하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.249-256
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• 2022

Various studies are being actively conducted to show that the real-time visualization technology that combines BIM (Building Information Modeling) and AR (Augmented Reality) helps to increase construction management decision-making and processing efficiency. However, when large-capacity BIM data is projected into AR, there are various limitations such as data transmission and connection problems and the image cut-off issue. To improve the high efficiency of visualizing, a mesh optimization algorithm based on the k-nearest neighbors (KNN) classification framework to reconstruct BIM data is proposed in place of existing mesh optimization methods that are complicated and cannot adequately handle meshes with numerous boundaries of the 3D models. In the proposed algorithm, our target BIM model is optimized with the Unity C# code based on triangle centroid concepts and classified using the KNN. As a result, the algorithm can check the number of mesh vertices and triangles before and after optimization of the entire model and each structure. In addition, it is able to optimize the mesh vertices of the original model by approximately 56 % and the triangles by about 42 %. Moreover, compared to the original model, the optimized model shows no visual differences in the model elements and information, meaning that high-performance visualization can be expected when using AR devices.

• Journal of dental hygiene science
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• v.13 no.4
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• pp.359-368
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• 2013

This study aimed to evaluate conditions and performance of quality improvement (QI) activity in Korean dental hospitals. Twenty one representative dental hospitals in Korea were selected by the selection criteria. A questionnaire was implemented to measure awareness, perceived needs, educations, conferences, works, activating/obstructive factors and satisfaction related to QI activities. Satisfaction score range from 0 (lowest) to 5 (highest) among 329 dental hygienists who worked in the selected 21 dental hospitals. Implementation rate of programs on external customer satisfaction was the highest 59.9% in QI activities, and reduction of expenses (59.4%), Improvement in health care quality (58.7), risk management (52.8) were followed, while improvement in work efficiency (46.5) showed the lowest implementation rate. The most influencing factor accelerating QI activities was 'active participation of hospital workers' (54.7%), and 'effort to improve customer satisfaction' (44.7%) followed. The most influencing QI related obstructive factor was 'lack of QI-related manpower and support' (47.1%). A balanced development including QI programs with lower implementation rates is necessary. Encouraging participation of workers may be the most important in developing dental QI activities further.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.126-133
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• 2019

This study intended to manufacture high quality cement, such as solving the quality problem of cement which has been emerging recently, along with improving grinding efficiency. To this end, the synthesis of melamine-functional pulverizing agents and the physical properties of cement applying them were reviewed and the reaction was carried out by dividing the melamine airborne compound into three stages of polymerization using methylation, sulfonation, and acid catalyst to improve the crushing efficiency of cement clinker and the physical properties of manufactured cement. The obtained melamine type copolymer was applied to the grinding process of cement clinker. And it's grinding efficiency and compressive strength were compared with DEG(diethylene glycol) and TIPA(triisopropanol amine). When it comes to the grinding efficiency, by lowering surface energy with stable adsorption from organic polymer to cement particles, the fineness showed 4-6% up. In the meantime, the compression strength hiked 30% from its initial strength compared to the conventional DEG. At the age of 28days, the strength showed approximately 13% improvement. Therefore, it is confirmed that the overall quality has been elevated in comparison with the conventional one.

• Journal of Korean Society of Archives and Records Management
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• v.21 no.3
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• pp.187-215
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• 2021

Archives should provide a web-based archival information service with good usability based on the understanding of users' needs. Thus, this study analyzed the usability of the National Archives of Korea (NAK) website's search service through expert and usability evaluations for various users and suggested improvement plans. A literature review, heuristic evaluation, one of the usability expert evaluation methods, and usability evaluation for users were performed. As a result of expert evaluation, the severity rating for the usability problem was highest regarding a match between the system and real world and the lowest in error prevention. In the usability evaluation, it was assumed that the user's background and whether the website's help was provided is associated with usability. Usability evaluation was conducted for 22 participants, including those majoring in records management, web/application developers, and people without such backgrounds. Furthermore, a presurvey, a five-second test, and search tasks were conducted in a row. The analysis based on usability components in ISO 9241-11: 2018, i.e., effectiveness, efficiency, and satisfaction, showed that web/application developers had the highest search effectiveness, and those majoring in records management showed high effectiveness only in the search for archival content services. Background factors did not affect efficiency, and the more familiar with the finding aids, the better the efficiency. Moreover, providing the website's help was found to be positively associated with effectiveness and satisfaction. This study suggests that the NAK website will offer a user-friendly interface and search function, expand help support, and display a consistent web interface.

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.604-608
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• 2015

In the present work, the improvement of nitrate removal ability was investigated to resolve a eutrophication problem by using Ulmus davidiana (U. davidiana) bark generated from Gangwon province. When the initial pH of aqueous solution was adjusted to 3.5 in batch experiments, the removal efficiencies for 10 and 20 mg/L nitrate increased up to 43 and 37%, respectively. In addition, when U. davidiana bark of 1.0 g/100 mL was used for 8 h, the removal efficiency for 20 mg/L nitrate was 68%. Moreover, when reforming reaction of U. davidiana bark was performed under oxyfluorination conditions, the optimal ratio of partial pressure between fluorine and oxygen was 1 : 9 for an enhanced nitrate adsorption amount. When reformed U. davidiana bark was used for 8 h operation under the optimal oxyfluorination condition, removal efficiencies for 10, 20 and 40 mg/L nitrate were found to be 96, 95 and 59%, respectively. Collectively, these results suggest that our water treatment technology can be effectively utilized to treat high concentrations of nitrate in water bodies.

• Journal of Korea Water Resources Association
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• v.44 no.5
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• pp.363-376
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• 2011

1-D hydrodynamic numerical models have been most widely used in the field of flood analysis. The model's input data are upstream/downstream boundaries, roughness coefficients, cross-sections, and so on, and computational distance step and time step are the most important factors in order to guarantee the computational accuracy, stability, and efficiency. In this study, a theoretical explanation is presented for the basis of the previous empirical selection criteria of cross-section's location; also, the estimation technique of computationally variable distance step is proposed to reflect the properties of flow at every computational time step. Combining this technique with 1-D unsteady numerical model, it was applied to two events of Teton dam failure flood and the Han River flood. The numerical experimental results demonstrate that the accuracy and stability is increased when used more interpolated cross-sections and show that the proposed technique of computationally variable distance step has the same order of accuracy with smaller numbers of cross-section than previous empirical selection criteria. The practical use of this technique will be possible to analyze the river floods with high efficiency as well as accuracy and stability.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.179-185
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• 2005

It is an essential subject to decrease the mass of a launch vehicle for improving performance and efficiency of space launch system. Particularly, reducing the engine supporting area is necessary for high efficiency of propulsion system with clustered engine systems. The engine supporting area is related to the branch location of the oxidizer feeding line. This article deals the performance variation of the propulsion system such as the mass of the oxidizer feeding line, pressurization pressure of the oxidizer tank, and the onset of nucleation boiling in the oxidizer pipe with the branch location of the main feeding line.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.9-17
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• 2010

In this paper we propose an improved hierarchical routing protocol for wireless hybrid mesh network. The proposed method efficiently manages network topology and reduces overhead traffic for setting routing path by considering link stability. The simulation results show that the proposed method outperforms the HOLSR (hierarchical optimized link state routing) method in aggregate goodput, packet delivery ratio, and end-to-end delay.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.1
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• pp.91-99
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• 2011

RFID is an important information technology that enables changes in existing methods of logistics. In this study, a decision making model for the introduction of RFID by domestic food & beverage businesses has been developed in order to enhance the efficiency of logistics activities. The general business states and effects expected from the introduction of RFID by SCM sector of 167 domestic food and beverage businesses were surveyed and based on the results, it was identified that generally positive answers were received. A decision making model for the introduction of RFID was derived and based on the results, it was identified that major influencing factors affecting the intention to introduce RFID were "the number of personnel" and "costs to introduce RFID".