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Heat transfer analysis in sub-channels of rod bundle geometry with supercritical water

  • Shitsi, Edward;Debrah, Seth Kofi;Chabi, Silas;Arthur, Emmanuel Maurice;Baidoo, Isaac Kwasi
    • Nuclear Engineering and Technology
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    • v.54 no.3
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    • pp.842-848
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    • 2022
  • Parametric studies of heat transfer and fluid flow are very important research of interest because the design and operation of fluid flow and heat transfer systems are guided by these parametric studies. The safety of the system operation and system optimization can be determined by decreasing or increasing particular fluid flow and heat transfer parameter while keeping other parameters constant. The parameters that can be varied in order to determine safe and optimized system include system pressure, mass flow rate, heat flux and coolant inlet temperature among other parameters. The fluid flow and heat transfer systems can also be enhanced by the presence of or without the presence of particular effects including gravity effect among others. The advanced Generation IV reactors to be deployed for large electricity production, have proven to be more thermally efficient (approximately 45% thermal efficiency) than the current light water reactors with a thermal efficiency of approximately 33 ℃. SCWR is one of the Generation IV reactors intended for electricity generation. High Performance Light Water Reactor (HPLWR) is a SCWR type which is under consideration in this study. One-eighth of a proposed fuel assembly design for HPLWR consisting of 7 fuel/rod bundles with 9 coolant sub-channels was the geometry considered in this study to examine the effects of system pressure and mass flow rate on wall and fluid temperatures. Gravity effect on wall and fluid temperatures were also examined on this one-eighth fuel assembly geometry. Computational Fluid Dynamics (CFD) code, STAR-CCM+, was used to obtain the results of the numerical simulations. Based on the parametric analysis carried out, sub-channel 4 performed better in terms of heat transfer because temperatures predicted in sub-channel 9 (corner subchannel) were higher than the ones obtained in sub-channel 4 (central sub-channel). The influence of system mass flow rate, pressure and gravity seem similar in both sub-channels 4 and 9 with temperature distributions higher in sub-channel 9 than in sub-channel 4. In most of the cases considered, temperature distributions (for both fluid and wall) obtained at 25 MPa are higher than those obtained at 23 MPa, temperature distributions obtained at 601.2 kg/h are higher than those obtained at 561.2 kg/h, and temperature distributions obtained without gravity effect are higher than those obtained with gravity effect. The results show that effects of system pressure, mass flowrate and gravity on fluid flow and heat transfer are significant and therefore parametric studies need to be performed to determine safe and optimum operating conditions of fluid flow and heat transfer systems.

The Rationalization of PDM in Pusan Port for the Period of Round Pacific Area (환태평양 시대의 부산항 물류산업 합리화)

  • Park, S. Y.;Park, C. S.
    • Journal of Korean Port Research
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    • v.6 no.1
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    • pp.93-110
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    • 1992
  • The most change in this century is supposed to be declination of ideology, and block of world economy. Addition to down full of cold war atmosphere around Northeast Asia, not only economic and social mood in this region is dramatically changed, but also it gave birth to the block of Northeast economy that accerlated new hub of world economy. According to dramatic change of economic surroundings the dynamic potential of growth in this region will be guided to enlarge inter-regional trade and increase volume of trade, thus suggests to grow steadily transportation. cargos in this region will have to arrange the system of delivery and inner transportation, accessary facilities, inter-regional harbors if North America and EC has connected easily. As have accerlated GATT and UR represented multilateralism and regionalism, it has regulated to increase trades of region due to relief of the trade barrier through specific areas has agreed with separately. The flow of regionalism of world economy has appeared to realize EC and NAFTA centered U.S.A, and also has presented to free trade region or one-size market agreement in Asia as APEC, EAEG in Malaysia, and etc. In defense to this block and internationalism of world economy, Pusan has to come forward to the hub of Northeast others has proposed a project to dominate the Northeast, Economy Association Agreement as Far East comprehensive development project in USSR, Hunchun development project in NK, and East Sea development project in PRC, Niigate regional development in Japan, Duman River development project in NK, and East Sea development project in Korea. As this exercise has proceed, Pusan also have arranged development strategy definitely and prepared provisions systematically. Engaging to participate center of delivery system is meant to be completed complex functions, namely the transfer storage processing & assembly function of international commodity. Pusan has ability to be terminal point of TSR. it had been connected to EC as the biggest economy block and TKR as complex transportation root to Far East, it would be the center of inground and seabase delivery terminal to Rotterdom as the biggest container pier and major piers to North-East and South East Asia. In order to provide a Role of 21 century's internationalization, Pusan has appealed to participate in management information research and development connected to Pohang-Ulsan-Changwon-Masan, and has utilized efficiently the resources such as man, material, money and information.

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Evaluation of the clinical and radiographic effectiveness of treating peri-implant bone defects with a new biphasic calcium phosphate bone graft: a prospective, multicenter randomized controlled trial

  • Jae-Hong Lee;Hyun-wook An;Jae-Seung Im;Woo-Joo Kim;Dong-Won Lee ;Jeong-Ho Yun
    • Journal of Periodontal and Implant Science
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    • v.53 no.4
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    • pp.306-317
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    • 2023
  • Purpose: Biphasic calcium phosphate (BCP), a widely used biomaterial for bone regeneration, contains synthetic hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), the ratio of which can be adjusted to modulate the rate of degradation. The aim of this study was to evaluate the clinical and radiographic benefits of reconstructing peri-implant bone defects with a newly developed BCP consisting of 60% β-TCP and 40% HA compared to demineralized bovine bone mineral (DBBM). Methods: This prospective, multicenter, parallel, single-blind randomized controlled trial was conducted at the periodontology departments of 3 different dental hospitals. Changes in clinical (defect width and height) and radiographic (augmented horizontal bone thickness) parameters were measured between implant surgery with guided bone regeneration (GBR) and re-entry surgery. Postoperative discomfort (severity and duration of pain and swelling) and early soft-tissue wound healing (dehiscence and inflammation) were also assessed. Data were compared between the BCP (test) and DBBM (control) groups using the independent t-test and the χ2 test. Results: Of the 53 cases included, 27 were in the test group and 26 were in the control group. After a healing period of 18 weeks, the full and mean resolution of buccal dehiscence defects were 59.3% (n=16) and 71.3% in the test group and 42.3% (n=11) and 57.9% in the control group, respectively. There were no significant differences between the groups in terms of the change in mean horizontal bone augmentation (test group: -0.50±0.66 mm vs. control groups: -0.66±0.83 mm, P=0.133), postoperative discomfort, or early wound healing. No adverse or fatal complications occurred in either group. Conclusions: The GBR procedure with the newly developed BCP showed favorable clinical, radiographic, postoperative discomfort-related, and early wound healing outcomes for peri-implant dehiscence defects that were similar to those for DBBM.

The gaze cueing effect depending on the orientations of the face and its background (얼굴과 배경의 방향에 따른 시선 단서 효과)

  • Lijeong, Hong;Min-Shik, Kim
    • Korean Journal of Cognitive Science
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    • v.34 no.2
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    • pp.85-110
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    • 2023
  • The gaze cueing effect appears as detecting a target rapidly and accurately when the direction of others' gaze corresponds with the location of the visual target. The gaze cue can be affected by the orientation of the face. The gaze cueing effect is strong when the face is presented upright, but the effect has only been observed in some studies when the face is presented inverted(e.g., Tipples, 2005). This study aimed to examine whether the gaze can operate as a cue to guide attention with upright faces, and to add variables that can affect the gaze cue, such as the orientation of the face, the orientation of the background, and a time interval between the gaze cue and the target(SOA). Furthermore, it systematically manipulated these variables to explore whether the gaze cueing effect can be observed under the various conditions. The results showed a significant gaze cueing effect even on the inverted face, contrasting with previous studies. These findings were consistently observed when the background stimulus was absent(Experiment 1) and present(Experiments 2 and 3). However, there was no significant interaction in the orientations between the face and the background. Moreover, in the short SOA(150 ms), we found a significant gaze cueing effect in conditions of every face and background orientation, whereas there was no significant gaze cueing effect in the long SOA(1000 ms). By presenting a consistent observation of the gaze cueing effect under the short SOA(150ms) even in the inverted faces, the results of this study pose questions about the reliability and repeatability of previous studies that did not report significant results of gaze cueing effects in that faces. Furthermore, our results are meaningful in providing additional evidence that attention can be guided toward the direction of the gaze even in various directions of the face and background.

In-silico annotation of the chemical composition of Tibetan tea and its mechanism on antioxidant and lipid-lowering in mice

  • Ning Wang ;Linman Li ;Puyu Zhang;Muhammad Aamer Mehmood ;Chaohua Lan;Tian Gan ;Zaixin Li ;Zhi Zhang ;Kewei Xu ;Shan Mo ;Gang Xia ;Tao Wu ;Hui Zhu
    • Nutrition Research and Practice
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    • v.17 no.4
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    • pp.682-697
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    • 2023
  • BACKGROUND/OBJECTIVES: Tibetan tea is a kind of dark tea, due to the inherent complexity of natural products, the chemical composition and beneficial effects of Tibetan tea are not fully understood. The objective of this study was to unravel the composition of Tibetan tea using knowledge-guided multilayer network (KGMN) techniques and explore its potential antioxidant and hypolipidemic mechanisms in mice. MATERIALS/METHODS: The C57BL/6J mice were continuously gavaged with Tibetan tea extract (T group), green tea extract (G group) and ddH2O (H group) for 15 days. The activity of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) in mice was detected. Transcriptome sequencing technology was used to investigate the molecular mechanisms underlying the antioxidant and lipid-lowering effects of Tibetan tea in mice. Furthermore, the expression levels of liver antioxidant and lipid metabolism related genes in various groups were detected by the real-time quantitative polymerase chain reaction (qPCR) method. RESULTS: The results showed that a total of 42 flavonoids are provisionally annotated in Tibetan tea using KGMN strategies. Tibetan tea significantly reduced body weight gain and increased T-AOC and SOD activities in mice compared with the H group. Based on the results of transcriptome and qPCR, it was confirmed that Tibetan tea could play a key role in antioxidant and lipid lowering by regulating oxidative stress and lipid metabolism related pathways such as insulin resistance, P53 signaling pathway, insulin signaling pathway, fatty acid elongation and fatty acid metabolism. CONCLUSIONS: This study was the first to use computational tools to deeply explore the composition of Tibetan tea and revealed its potential antioxidant and hypolipidemic mechanisms, and it provides new insights into the composition and bioactivity of Tibetan tea.

21Century of Combat Aspects of North Korean Attack Drones Through the War of the Century (21세기 전쟁을 통해 본 북한 공격 드론의 전투 양상 전망)

  • Kang-Il Seo;Sang-Keun Cho;Jong-Hoon Kim;Ki-Won Kim;Sang-Hyuk Park
    • The Journal of the Convergence on Culture Technology
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    • v.9 no.3
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    • pp.299-304
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    • 2023
  • Recently, drones have been used as a major means of attack drones in major wars around the world, and it seems likely that they will evolve into game changers in the future. Recently, drones have been used as a major means of attack drones in major wars around the world, and it seems likely that they will evolve into game changers in the future. In the major wars of the 21century, attack drones are used for precision fire-guided or self-destruct attacks, For the purpose of cognitive warfare, its territory is expanding not only to land and air, but also to sea and water. These attack drones will perform multi-domain operations, and for this purpose, the level of autonomy will be improved and High-Low Mix We will continue to develop by strengthening concept-based scalability. North Korea has also been making considerable efforts to operate attack drones for a long time, and activities such as third-country-level self-explosive drones, artificial intelligence-based clustered self-explosive drones, and self-destructive stealth unmanned semi-submersible are expected. In addition to North Korea's provocations and attacks, it is hoped that there will be a need for active follow-up research on our military's countermeasures and utilization plans.

A Case Study on Autobiography Writing Program for Older Adults (노인자서전 쓰기 교육 프로그램 사례 연구)

  • Ji, Haeng Jung;Han, Jungran;Park, Seong Hie
    • 한국노년학
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    • v.31 no.2
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    • pp.223-241
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    • 2011
  • The purpose of this research is to analyze the effect of an autobiography writing program as a method of education for older adults. The authors participated in the processes of all 10 sessions of the autobiography writing program as instructors or program assistants at a senior welfare center in Seoul, 2007. Data used for analysis were learners' narrations in class, written autobiographies by learners, and researchers' memo-notes. We analyzed their narrative flows using Haenninen(2000)'s theory of narrative flow and reconstructed their categories of activities as life histories. 'The innen narration' constructed by learners was a spiritual process in which they have imbued their life and living conditions with meaning. The learners reminisced their lives as 'unreflective narration' in the beginning of education. However, as the class went on, they gradually reminisced them as "reflective narration" and finally developed them as 'meta-reflective narration' through the intentional reflection. Likewise, we could interpret the transition of learners into meta-reflecter as the completion of ego-integration. As a conclusion, we found the effects of the autobiography writing education for older adults in educational, social, and psychological aspects.

Full mouth rehabilitation using 3D printed crowns and implant assisted removable partial denture for a crossed occlusion: a case report (3D 프린팅 금관과 임플란트 보조 국소의치를 이용한 엇갈린 교합의 전악 수복 증례)

  • Sung-Hoon Lee;Seong-Kyun Kim;Seong-Joo Heo;Jai-Young Koak;Ji-Man Park
    • The Journal of Korean Academy of Prosthodontics
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    • v.61 no.4
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    • pp.367-378
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    • 2023
  • With the recent development of computer-aided design-computer-aided manufacturing technology and 3D printing technology, and the introduction of various digital techniques, the accuracy and efficiency of top-down definitive prosthetic restoration are increasing. In this clinical case, stable occlusion support was obtained through the placement of a total of 9 maxillary and mandibular posterior implants in patient with anterior-posterior crossed occlusion. The edentulous area of the maxillary anterior teeth, which showed a tendency of high resorption of the residual alveolar bone, was restored with a Kennedy Class IV implant assisted removable partial denture to restore soft tissue esthetics. Computed tomography guided surgery was used to place implants in the planned position, double scan technique was used to reflect the stabilized occlusion in the interim restoration stage to the definitive prostheses, and metal 3D printing was used to manufacture the coping and framework. This clinical case reports that efficient and predictable top-down full mouth rehabilitation was achieved using various digital technologies and techniques.

Treatment with upper complete denture and lower implant-fixed restorations on an elderly patient presenting fully edentulous maxilla and bilateral posterior edentulous mandible: a case report (상악 완전무치악 및 하악 양측 구치부 결손 고령환자에 대한 상악 가철성, 하악 고정성 보철치료: 증례보고)

  • Joseph Junesirk Choi;Richard Leesungbok;Suk-Won Lee;Phyo Ei Ei Htay;Jeong-yun Park;Jin-Young Chon
    • The Journal of Korean Academy of Prosthodontics
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    • v.61 no.4
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    • pp.284-292
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    • 2023
  • Stable posterior occlusal support is crucial for adequate masticatory function and facial aesthetics. In elderly patients over the age of 65, masticatory ability has a significant impact on nutritional intake and overall health. This case report presents a prosthetic treatment of an elderly patient with edentulous maxilla and bilateral posterior edentulous mandible. The upper jaw was restored with a complete denture to establish an ideal occlusal plane, and the three-dimensional positions of the mandibular implants were determined accordingly. The implants were placed through computer-guided implant surgery and were immediately loaded with fixed provisional restorations. The implant-fixed zirconia final restorations were inserted in the lower posterior region, and the occlusal surface of posterior artificial teeth in the upper denture was substituted with cobalt-chrome alloy to resist occlusal wear. The patient's posterior occlusal support and masticatory function were promptly restored through this treatment process, and long-term stability against wear was also obtained.

Review of International Cases for Managing Input Data in Safety Assessment for High-Level Radioactive Waste Deep Disposal Facilities (고준위방사성폐기물 심층처분시설 안전성평가 입력자료 관리를 위한 해외사례 분석)

  • Mi Kyung Kang;Hana Park;Sunju Park;Hae Sik Jeong;Woon Sang Yoon;Jeonghwan Lee
    • Economic and Environmental Geology
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    • v.56 no.6
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    • pp.887-897
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    • 2023
  • Leading waste disposal countries, such as Sweden, Switzerland, and the United Kingdom, conduct safety assessments across all stages of High-Level Radioactive Waste Deep Geological Disposal Facilities-from planning and site selection to construction, operation, closure, and post-closure management. As safety assessments are repeatedly performed at each stage, generating vast amounts of diverse data over extended periods, it is essential to construct a database for safety assessment and establish a data management system. In this study, the safety assessment data management systems of leading countries, were analyzed, categorizing them into 1) input and reference data for safety assessments, 2) guidelines for data management, 3) organizational structures for data management, and 4) computer systems for data management. While each country exhibited differences in specific aspects, commonalities included the classification of safety assessment input data based on disposal system components, the establishment of organizations to supply, use, and manage this data, and the implementation of quality management systems guided by instructions and manuals. These cases highlight the importance of data management systems and document management systems for securing the safety and enhancing the reliability of High-Level Radioactive Waste Disposal Facilities. To achieve this, the classification of input data that can be flexibly and effectively utilized, ensuring the consistency and traceability of input data, and establishing a quality management system for input data and document management are necessary.