• Title/Summary/Keyword: long-term bed chan

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A Study on the Optimal Sediment Discharge Formula for Hyeongsan River (형산강 수계 최적 유사량 공식 선정을 위한 연구)

  • Ahn, Jung-Min;Lyu, Si-Wan;Lee, Nam-Joo
    • Journal of Korea Water Resources Association
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    • v.43 no.11
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    • pp.977-984
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    • 2010
  • In order to determine the optimal sediment discharge formula for Hyeongsan river, some statistical approaches have been applied to analyze the simulated results of long-term bed change by HEC-6. The field measurements have been conducted to obtain the data for model calibration and verification such as sediment discharge, bed material, and channel geometry. Several sediment discharge formulae have been verified according to the bias, RMSE, RRMSE, discrepancy ratio, and S/N ratio of bed change along the thalweg. Comparing the formulae, Laursen formula(modified by Copeland) have shown the best performance to simulate the long-term bed change of Hyeongsan river.

The Parametric Study on the Performance Characteristics of Elastic Rail Fastening System on the Sharp Curved Track (급곡선 탄성레일체결장치의 거동특성에 미치는 매개변수 연구)

  • Baik, Chan-Ho;Joo, Bong-Gyu;Choi, Jung-Youl;Choi, Il-Yoon;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.2163-2173
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    • 2011
  • In this study, the deformations and stresses occurred in the elastic rail fastening system were evaluated according to applied extreme track forces based on various field conditions, track curvature and poor properties. The purpose of this study is to establish a method for efficient management and suggest guide line for track construction in order to secure the performance quality of the elastic rail fastening system on the sharp curved track.. Therefore, initial construction qualities of rail and concrete bed, initial clamping force and applied extreme track forces were used into experiment as several parameters. Using these test results, the performance characteristics of the elastic rail fastening system were also evaluated. As a result, it suggested the method to secure long-term durability of fastening system and comparing sharp curved track to results on field test.

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Evaluation on the Possibility of a Retrofitting Treatment Using Moving Media of Existing Wastewater Treatment (유동상 Media를 이용한 기존하수처리장의 Retrofitting 가능성 평가)

  • Ko, Tae-Ho;Park, Woon-Ji;Lee, Chan-Ki
    • Journal of Industrial Technology
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    • v.25 no.A
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    • pp.133-139
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    • 2005
  • In this study, as MBBR(Moving Bed Biofilm Reactor) process using waste tire media is suggested for retrofitting with advanced wastewater treatment and the removal property of organic matter and nutrient and the capacity of media are evaluated through long-term operation with pilot plant following seasons, the application capacity of retrofitting with MBBR process to a existing wastewater treatment is studied. As a result of the long-term operation of the process, it is proved that there is no loss and abrasion of media, and also that it is possible to secure the sufficient attached bio-mass. The values of organic matter and nutrient in effluent are suitable for the strict discharged water quality standards in every season including winter.

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A Riverbed Change Prediction by River-Crossing Structure -Focused on the Major River Reaches of the Multifunctional Administrative City- (하천 횡단구조물에 의한 하상변동 예측 - 행정중심복합도시 주요 하천구간을 중심으로 -)

  • Yeon, Kyu-Sung;Jeong, Sang-Man;Yun, Chan-Young;Lee, Joo-Heon;Shin, Kwang-Seob
    • Journal of the Korean Society of Hazard Mitigation
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    • v.9 no.1
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    • pp.107-113
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    • 2009
  • This study has been conducted for the long-term riverbed change prediction on Geum River and Miho Stream surrounding the planned Multifunctional Administrative City and the neighboring regions by the construction of a small dam. Based on the analysis of vertical riverbed changes of the cross-sectional data for the years 1988, 2002 and 2007, minimum bed elevation significantly decreased in both Geum River and Miho Stream in 2007 as compared to 1988. Compared to 2002, however, a slight elevation change was observed. To make a long-term prediction on riverbed changes by the construction of a small dam, a one dimensional HEC-RAS 4.0 model has been used. By the fixed bed model test, the water levels were calibrated. By using the cross-sectional data of 1988 and 2002, verification was conducted under a movable bed model. According to the prediction of riverbed changes for each scenario with varying height of small dam, minor impact is expected around Miho Stream while major impact is expected around Geum River by 2017, as the small dam height increases. If the small dam is 7m-high, for example, it's been simulated that 1.59m deposition would be expected around the upper stream of Miho Stream Confluence while 1.98m scour would be expected around the downstream of the small dam.

Characteristics of Behavior of the Soft Roadbed through Long-Term Instrumentation on the Field Test (운행선상의 연약노반 시험부설구간에서의 장기계측을 통한 거동 특성)

  • Lee Jin-Wook;Choi Chan-Yong;Lee Sung-Hyok;Lee Cnang-Youl
    • Proceedings of the KSR Conference
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    • 2004.10a
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    • pp.1058-1064
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    • 2004
  • As one of reinforcing methods for soft roadbed, the problems that mud-pumping and settlement occurred by soft roadbed, were investigated, evaluated and analyzed through installing relatively economical and efficient geosynthetics on the selected track-bed for testing. Mock-heang to Dong-ryang on the filed resting sections in the Chung-buk lines were selected as investigating the state of track and prepared field after selecting three of 1,700 spots which often make mud-pumping and requiting maintenance for that. Long curved line radiuses(R) of Mock-heang to Dong-ryang are 500m that were installed with 4 types of geosynthetics layers and one ballast layer. Installed testing cross-section is 200m totally with 40 m between places. Strength or prepared roadbed was measured to investigate the state of roadbed and track with constructing(installing) field testing sections and physical properties of roadbed soils were evaluated and analyzed. Also, mud-pumping, settlement of elastic or plastic sleeper, failure or track, wheel-loads, transverse and earth pressures were measured after installing field testing sections.

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A Study on Reinforcement Effectiveness for Railway Soft Roadbed through Long-Term Instrumentation on the Field Test (현장부설시험구간에서의 장기계측을 통한 토목섬유 보강효과)

  • Choi Chan-Yong;Lee Jin-Wook
    • Proceedings of the KSR Conference
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    • 2005.05a
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    • pp.734-743
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    • 2005
  • In this study, geotextiles was applied on the selected track-bed, which is relatively economical and efficient way to prevent the problem of mud-pumping and settlement. Field testing sections from Mock-haeng to Dong-ryang in the Chung-La lines in Korea were selected to investigate the state of track and roadbed. And three places were chosen among 1,700 spots where mud-pumping was frequently occurred and maintenance required. At the curved section with radius of 500m between Mock-haeng and Dong-ryang, we divided this testing site into 5 section and 4 different types of geotextile were installed and left the last section with no reinforcement. Total length of the test site was 200m and individual length of each site was 40 m. In order to understand the state and the strength of prepared roadbed, stiffness and physical properties of the roadbed soil were evaluated and analyzed. Also, after the installation, mud-pumping, settlement of elastic or plastic sleeper, failure of track, wheel-loads, lateral force and earth pressures were investigated.

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Hydraulic Compressor Safety Test for Hydrogen Stations (수소충전소용 유압식 압축기 안전성 시험에 관한 연구)

  • Seong, Hye-Jin;Hwang, Bom-Chan;Choi, Sung-Joon;Kim, Young-Kyu;Cho, Sung-Min
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.11
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    • pp.8-15
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    • 2020
  • The government has announced its Hydrogen Economy Roadmap to strengthen global competitiveness on the hydrogen economy by focusing on hydrogen fuel cell electric vehicles and fuel cells. In this regard, the interest on the economics and safety of the infrastructure of hydrogen stations has also increased. In this study, a test bed similar to an actual hydrogen charging facility was built, and a prototype of a piston-type compressor was modeled. In this model, the piston was hydraulically compressed to progressively test leakage, leakage rate, and durability and to check for any malfunction. Moreover, the leakage rate, cylinder leak performance, and compressor operation durability were evaluated for safety; it was confirmed that there were no abnormalities. Nevertheless, an investigation of the long-term use and operating pressure of the compressor is necessary to verify the safety of developing a100-MPa domestic compressor in the future.

Glomus Tumor of the Hand

  • Lee, Won;Kwon, Soon Beom;Cho, Sang Hun;Eo, Su Rak;Kwon, Chan
    • Archives of Plastic Surgery
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    • v.42 no.3
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    • pp.295-301
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    • 2015
  • Background Glomus tumors were first described by Wood in 1812 as painful subcutaneous tubercles. It is an uncommon benign neoplasm involving the glomus body, an apparatus that involves in thermoregulation of cutaneous microvasculature. Glomus tumor constitutes 1%-5% of all hand tumors. It usually occurs at the subungual region and more commonly in aged women. Its classical clinical triad consists of pain, tenderness and temperature intolerance, especially cold sensitivity. This study reviews 15 cases of glomus tumor which were analyzed according to its anatomic location, surgical approach and histologic findings. Methods Fifteen patients with subungual glomus tumors of the hand operated on between January 2006 and March 2013, were retrospectively reviewed. Patients were evaluated preoperatively with standard physical examination including ice cube test and Love's test. Diagnostic imaging consisted of ultrasonography, computed tomography, and magnetic resonance imaging. All procedures were performed with tourniquet control under local anesthesia. Eleven patients underwent excision using the transungual approach, 3 patients using the volar approach and 1 patient using the lateral subperiosteal approach. Results Total of 15 cases were reviewed. 11 tumors were located in the nail bed, 3 in the volar pulp and 1 in the radial aspect of the finger tip. After complete excision, patients remained asymptomatic in the immediate postoperative period. In the long term follow up, patients exhibited excellent cosmetic results with no recurrence. Conclusions Accurate diagnosis should be made by physical, radiologic and pathologic examinations. Preoperative localization and complete extirpation is essential in preventing recurrence and subsequent nail deformity.

Long-term Variation and Flux of Organic Carbon in the Human-disturbed Yeongsan River, Korea (영산강의 유기물 플럭스와 장기변동에 대한 연구)

  • CHO, HYEONG-CHAN;CHO, YEONG-GIL
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.22 no.4
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    • pp.187-198
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    • 2017
  • Dissolved and particulate organic carbon concentrations and fluxes were measured and estimated for the Yeongsan River during 2006~2015. The dissolved organic carbon (DOC) concentrations ranged from 2.49 to $4.39mg{\cdot}C/L$ with a variance of 30.1% (${\sigma}_x/\bar{x}$), and showed a simple correlation to algal bloom and precipitation. The particulate organic carbon (POC) concentrations had gradually decreased from 6.68 to $0.19mg{\cdot}C/L$ for 10 years, and changed definitely with weir construction in 2011. Based on the relationships between POC and suspended particulate matters and between POC and chlorophyll-a, we found out that the distinct variation of the origin and composition of POC was caused by stagnation and screening effect of the dammed river. The total organic carbon (TOC) concentrations dropped to 52.3% (from 8.26 to $3.94mg{\cdot}C/L$) as the POC concentrations diminished to more than 94.8% after weir construction, in which the DOC forms up to 90.9%. The fluxes of TOC, based on the relationship between the annual TOC concentration and the discharge of Yeongsan dike sluice, were $2.56{\sim}19.41{\times}10^9g{\cdot}C/yr$, and showed a great deal of variability in 2011. Since then the TOC flux dropped to $5.40{\times}10^9$ (2011~2015) from $14.54{\times}10^9g{\cdot}C/yr$ (2006~2010). These results suggest that the weirs trapped annually $1.83{\times}10^9g{\cdot}C$ on a river bed, but released in great levels of dissolved organic form at their exits.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.