• Journal of Biomedical Engineering Research
• /
• v.43 no.2
• /
• pp.116-123
• /
• 2022

This study analyzes the Mechanical properties of a medical bone plate by 3D printing. With the recent development of 3D printing technology, it is being applied in various fields. In particular, in the medical field, the use of 3D printing technology, which was limited to the existing orthosis and surgical simulation, has recently been used to replacement bones lost due to orthopedic implants using metal 3D printing. The field of application is increasing, such as replacement. However, due to the manufacturing characteristics of 3D printing, micro pores are generated inside the metal printing output, and it is necessary to reduce the pores and the loss of mechanical properties through post-processing such as heat treatment. Accordingly, the purpose of this study is to analyze the change in mechanical performance characteristics of medical metal plates manufactured by metal 3D printing under various conditions and to find efficient metal printing results. The specimen to be used in the experiment is a metal plate for trauma fixation applied to the human phalanx, and it was manufactured using the 'DMP Flex 100(3D Systems, USA), a metal 3D printer of DMLS (Direct Metal Laser Sintering) method. It was manufactured using the PBF(Powder Bed Fusion) method using Ti6Al4V ELI powder material.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.28 no.4
• /
• pp.61-69
• /
• 2022

Purpose: In response to the rapid spread of COVID-19 in 2020, the government supported facilities and equipment through the 'Urgent Isolation Ward Expansion Project'. Design and remodeling of efficient negative pressure isolation facilities had to be done in a short period of time, and the performance gap between facilities was very large because the types of hospitals and wards of existing medical facilities were diverse. In order to secure the stability of isolation wards between medical facilities and reduce the facility gap, guidelines for planning isolation wards considering the diversity of each hospital should be appropriately presented. In consideration of these points, this study aims to provide basic data for future remodeling guidelines for each plan type of the negative pressure isolation ward first. Methods: We analyzed the plans before and after the change of 13 case hospitals that performed the urgent care bed expansion project for COVID-19 confirmed patients. Before the remodeling, the current status of the facility was analyzed according to the type of corridor, the location of the nursing station, and the location of the elevator. After remodeling, the flow of medical staff and patients, the flow of entry and exit of clean and contaminated items, and the space of negative pressure and non-negative pressure areas. Results: The ward type was divided into three types according to the corridor type and room arrangement: double loaded corridor type with two side wards, race track type with one side ward, and race track type with two side wards. Based on these three types, the standard floor plan type of the isolation ward was proposed in terms of the location of the elevator bank and Nurse station. Implications: When the existing general ward is converted into a negative pressure isolation ward, this study can be a basic data to present customized guidelines for each ward type.

• Journal of the Society of Naval Architects of Korea
• /
• v.58 no.6
• /
• pp.366-374
• /
• 2021

This paper presents the analysis of the speed-power performance in the real sea using a large container vessel data provided as a test bed from a shipping company. To perform a speed trial of the vessel during a commercial voyage, the on-board measuring device and various operation data acquisition systems were mounted on the vessel for long-term performance monitoring and the voyage operated under the container loading condition close to the design draft was adopted. The content of this paper consists of Part I and Part II. Part I, such as this paper, contains the speed trial method and analysis results of the operating vessel. Part II contains the analysis of the speed-power characteristics change over time and before and after hull cleaning using operation data measured from the voyage operated under a condition similar to the speed trial.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.5
• /
• pp.547-552
• /
• 2022

In this study, shape-based track management by analyzing track irregularity was studied in terms of force-based track irregularity analysis by numerical analysis of wheel-rail interaction force using by the measured vertical irregularity. The effect of the vertical irregularity of the track due to the difference in track types on the wheel-rail interaction force and the track acceleration in the connecting section of the sleeper floating track and the direct fixation track on concrete bed were analyzed. As the results of this study, the measured vertical irregularity was directly affect the vertical wheel load (the wheel-rail interaction force) and the rail acceleration, and it has been demonstrated to change consistently. In this study, the adequacy and necessity of the force-based track irregularity analysis method was verified based on the wheel-rail interaction analysis using the the measured vertical irregularity.

• Journal of the Korean Institute of Gas
• /
• v.27 no.1
• /
• pp.78-85
• /
• 2023

Fixed-bed reactor Computational Fluid Dynamics (CFD) simulation of methanol steam reforming reaction was performed using the intrinsic kinetic data of the copper-impregnated hydrotalcite catalyst. The activation energy of the copper hydrotalcite catalyst obtained from the previous study results was 97.4 kJ/mol, and the pre-exponential was 5.904 × 10¹⁰. Process simulation was performed using the calculated values and showed a similar tendency to the experimental results. And the conversion rate according to the change of the reaction temperature (200 - 450 ℃) and the molar ratio of methanol and water was observed using the intrinsic kinetic data. In addition, mass and heat transfer phenomena analysis of a commercial reactor (I.D. 0.05 - 0.1m, Length 1m) was predicted through axial 2D Symmetry simulation using the power law model of the above kinetic constants.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.153-153
• /
• 2021

Storm Storm event is one of major issues in South Korea due to devastating damage at its landfall. A series of statistical study on the historical typhoon records consistently insist that the typhoon translation speed (TS) is on slowdown trend annually, and thus provides an urgent topic in assessing the extreme storm surge under future climate change. Even though TS has been regarded as a principal contributor in storm surge dynamics, only a few studies have considered its impact on the storm surge. The landfall angle (LA), another key physical factor of storm surge also needs to be further investigated along with TS. This study aims to elucidate the interaction mechanism among TS, LA, coastal geometry, and storm surge synthetically by performing a series of simulations on the idealized geometries using Delft3D FM. In the simulation, various typhoons are set up according to different combinations of TS and LA, while their trajectories are assumed to be straight with the constant wind speed and the central pressure. Then, typhoons are subjected to make landfall over a set of idealized geometries that have different depth profiles and layouts (i.e., open coasts or bays). The simulation results show that: (i) For the open coasts, the maximum surge height (MSH) increases with increasing TS. (ii) For the constant bed level, a typhoon normal to the coastline resulted in peak MSH due to the lowest effect of the coastal wave. (iii) For the continental shelf with different widths, the slow-moving typhoon will generate the peak MSH around a small LA as the shelf width becomes narrow. (iv) For the bay, MSH enlarges with the ratio of L/E (the length of main-bay axis /gate size) dropping, while the greatest MSH is at L/E=1. These findings suggest that a fast-moving typhoon perpendicular to the coastline over a broad continental shelf will likely generate the extreme storm surge hazard in the future, as well as the slow-moving typhoon will make an acute landfall over a narrow continental shelf.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.21-21
• /
• 2021

효과적인 하천의 유지 및 관리를 위해서는 준설과 각종 수리시설물 영향에 의한 하상변화 양상을 파악하는 것이 필수적이다. 일반적으로 하상변화 분석을 위해서는 하도지형, 하상재료, 유사량 등 현장계측자료가 요구되지만, 대하천 주요 지점이나 정기조사가 이루어지는 일부 지점이 아니라면 하상변화 분석을 위한 현장계측자료가 부족한 실정이다. 따라서 하천을 효율적으로 관리하고 운영하기 위해서는 장래 하상변화 양상을 분석하는데 필요한 충분한 공간적 해상도를 가지는 지형정보와 하상재료 및 유사량 계측자료가 필요하며, 이를 기반으로 중기 및 장기 하상변화를 예측하고 그에 따른 하천관리계획을 수립하게 된다. 본 연구에서는 하도지형 현황자료의 공간해상도가 하상변화의 양적 규모 평가에 미치는 영향을 평가해보고자 한다. 현행 낙동강과 같은 대하천 하도의 하상변동 관련된 조사 및 연구 분석에는 500 m 간격을 기준으로 설정된 기준상의 측선 자료를 이용한다. 본 연구방법으로는 기존 측선을 이용하여 산정된 체적하상변동량과 기준 측선 사이 구간에 대해 측정된 보조측선에 대한 지형정보를 함께 활용하여 산정한 체적하상변동량을 비교함으로써, 하도지형자료의 해상도에 따른 체적변동량 산정결과의 차이와 영향을 평가하였다. 비교를 통해 기존 측선기준 하상변동량 산정치가 실체 하상변동량과 큰 차이를 보일 수 있음을 확인하였다. 따라서 효과적인 하천의 유지 및 관리와 계획 수립을 위해서는 보다 높은 공간해상도의 하도지형자료를 기반으로 한 하상변동 평가 및 분석의 정확도 제고가 필요한 것으로 판단된다. 향후 본 연구 성과를 장래의 하상변화조사의 기초자료로 활용시 상기의 문제점(자료 품질, 추정 자료 사용 등)을 해결하여 모의의 정확성과 정밀성을 제고할 수 있을 것으로 기대되는 바이다.

• Journal of Ecology and Environment
• /
• v.48 no.1
• /
• pp.85-95
• /
• 2024

Background: In Korea, riparian zones and some floodplains have been converted into agricultural fields and urban areas. However, there are essential for maintaining biodiversity, as they are important ecological spaces. There are also very important spaces for humanity, as they perform various ecosystem services in a changing environment including climate change. Due to the importance of rivers, river restoration projects have been promoted for a long time, but their achievement has been insignificant. Development should be pursued by thoroughly evaluating the success of the restoration project. Ecological restoration is to accelerate succession, a process that a disturbed ecosystem recovers itself, with human assistance. Ecological restoration can be a test bed for testing ecological theories in the field. In this respect, ecological restoration should go beyond a 'simple landscaping exercise' and apply ecological models and theories in restoration practice. Results: The cross-section of the restored stream is far from natural rivers due to its steep slope and artificial material. The vegetation profiles of the restored streams did not reflect the flooding regime of the river. The species composition of the vegetation in the restored stream showed a significant difference from that of the reference stream, and was also different from that of an unrestored urban stream. Although species richness was high and the proportion of exotic species was low in the restored stream, the effect was offset by the high proportion of gardening and landscaping plants or obligate terrestrial plants. Conclusions: Based on both the morphological and ecological characteristics of the river, the restoration effect in the restored stream was evaluated to be very low. In order to solve the problems, a systematic adaptive management plan is urgently required. Furthermore, it is necessary to institutionalize the evaluation of restoration effects for the development of river restoration projects in the future.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.24 no.2
• /
• pp.78-82
• /
• 1988

Near sea trawlers of Korea sometimes catch pelagic fishes like file fish by using midwater trawl gear even though usually catch bottom fish. It is reasonable to use the specific otter board as well as specific net in bottom trawling and in midwater trawling respectively. But, the trawlers are so small ranging 100 to 120GT, 700 to 100ps that it is very complicated to use different otter board for bottom trawling and for midwater trawling. The otter board for bottom trawling. is also used for the midwater trawling without any change even though the net is changed into the specific one. Although the otter board in the midwater trawling should be lighter than that for bottom trawling, to use otter board for bottom trawling directly for the midwater trawling without any change makes the net easily touch the sea bed and also make the horizontal opening of the otter boards be limited owing to the length of warp in the southern sea of Korea, main fishing ground of midwater trawling, which is 100m or so in depth. That is why the otter board for the midwater trawling should be made lighter than that in the bottom trawling, even if temporary. The authors carried out an experiment to achieve this purpose by attaching a large styropol float on the top of the otter board. In this experiment, underwater weight of the otter board was 630kg and buoyancy of the float was 510kg. To determine the depth and horizontal opening of the otter board, two fish finder was used. A transmitter of 50KHz fish finder was set downward through the shoe plate of otter board to determine the elevation of otter board from the sea bed, and a transmitter of 200KHz fish finder was set sideways on the starboard otter board to be able to detect the distance between otter boards. The obtained results can be summarized as follows: 1. The actual towing speed in the experiment varied 1.1 to 1.8 m/sec. 2. The depth of otter board was within 41 to 25m with float on the top and 45 to 26m without float in case of the warp length 100m, whereas the depth 68-44m with float and 74-46m without float in case of the warp length 150m. This fact means that the depth with float was 9-4% shallower than that without float. 3. The horizontal opening between otter boards was within 34-41m with float and 30-38m without float in case of the warp length 100m, whereas the opening was 44-50m with float and 37-46m without float in case of the warp length 150m. This fact means the opening with float was 10% greater than that without float in case of the warp length 100m, and 15% greater in case of the warp length 150m. 4. The horizontal opening between wing tips by using the otter board with float was 1m greater than by without float in case of the warp length 100m, whereas the opening by with float was 2m greater than by without float in case of warp length 150m. From this fact, it can be estimated that the effective opening area of the net mouth by using the otter board with float could be made 10% greater than by without float in case of warp length 100m, whereas the area with float 20% greater than by without float in case of warp length 150m.

• Ecology and Resilient Infrastructure
• /
• v.4 no.3
• /
• pp.169-179
• /
• 2017

This study analyzed the aspect of bed change according to the stable channel design on the Wonju River to quantitatively evaluate habitat suitability (HS). According to the result of evaluating stable channel of object section in the Wonju River, 17 sections among total 20 sections were stable and 3 sections were unstable. Physical disturbance improvement evaluation (PDIE) was the range average showed good disturbance condition with a range average of 112.17 points. Habitat suitability index of Zacco Koreanus, the most dominant species of the Wonju River, was used for analysis of physical habitat for fish. According to the physical habitat analysis result, HS was 0.16 and weighted usable area (WUA) was $347.68m^2$. The methods of improving/introducing/removing structures and dredging stream channel were used for stable channel design of unstable channel, and analyzed PDIE according to the aspect of bed change and changes in habitat suitability. Stable channel design was possible in 19 sections in times of structures improvement/introduction/removal, and PDIE was 117.53 points, HS was 0.14 points, and WUA was $313.37m^2$. Stable channel design was possible in all 20 sections when dredging the stream channel. PDIE was 116.50 points, HS was 0.16, and WUA was $332.14m^2$. Therefore, this study obtained channel design measures that can improve physical soundness and stability of the Wonju River, and it was analyzed that it will have no impact on changes of physical disturbance and physical habitat. Furthermore, this study analyzed velocity and depth of each section and appearance frequency of riffle and pool to analyze correlation between physical disturbance and physical habitat. According to the analysis result, it was identified that the analysis of riffle and pool showed similar result as the evaluation result of physical habitat.