• Title/Summary/Keyword: Tunnel flow

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지하시설물(구조물형) 데이터 품질검증방법 개선방안 연구 (A Study on Improving the Data Quality Validation of Underground Facilities(Structure-type))

  • 배상근;김상민;유은진;임거배
    • 지적과 국토정보
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    • 제51권2호
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    • pp.5-20
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    • 2021
  • 지하공간통합지도는 2014년도에 전국적으로 발생했던 싱크홀을 계기로 15종의 지하정보를 통합한 국가공간정보로서, 2015년부터 지속적으로 구축되고 있다. 그러나 최근까지도 온수관 파열, 통신구 화재, 지반 침하 등과 같은 지하공간에서의 재난·재해가 지속적으로 발생함에 따라 지하정보의 품질 향상에 대한 요구가 증대되고 있는 실정이다. 이에 본 논문에서는 지하공간통합지도 데이터의 품질 향상을 위한 방안을 마련하고자 하였다. 특히 지하공간통합지도를 통해 관리되는 15종의 지하정보 중 신규 구축 비중이 가장 높은 지하시설물(구조물형) 데이터의 품질검증 개선 방안을 제시하였다. 대부분 육안검수로 진행되고 있는 현재의 검수 방식을 개선하기 위해 품질검사 기준을 좀 더 구체화·세분화하고자 하였다. 이를 위해 현재 품질요소, 세부요소, 세세부요소, 품질검사 기준으로 구성된 검사항목에 품질검사 방법, 품질검사 규칙, Flow Diagram, 해결 가능 오류 유형 항목을 추가하여 속성정보 뿐 아니라 도형정보까지 소프트웨어로 자동검수하기 위한 알고리즘을 개발하였다.

Multi-fidelity uncertainty quantification of high Reynolds number turbulent flow around a rectangular 5:1 Cylinder

  • Sakuma, Mayu;Pepper, Nick;Warnakulasuriya, Suneth;Montomoli, Francesco;Wuch-ner, Roland;Bletzinger, Kai-Uwe
    • Wind and Structures
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    • 제34권1호
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    • pp.127-136
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    • 2022
  • In this work a multi-fidelity non-intrusive polynomial chaos (MF-NIPC) has been applied to a structural wind engineering problem in architectural design for the first time. In architectural design it is important to design structures that are safe in a range of wind directions and speeds. For this reason, the computational models used to design buildings and bridges must account for the uncertainties associated with the interaction between the structure and wind. In order to use the numerical simulations for the design, the numerical models must be validated by experi-mental data, and uncertainties contained in the experiments should also be taken into account. Uncertainty Quantifi-cation has been increasingly used for CFD simulations to consider such uncertainties. Typically, CFD simulations are computationally expensive, motivating the increased interest in multi-fidelity methods due to their ability to lev-erage limited data sets of high-fidelity data with evaluations of more computationally inexpensive models. Previous-ly, the multi-fidelity framework has been applied to CFD simulations for the purposes of optimization, rather than for the statistical assessment of candidate design. In this paper MF-NIPC method is applied to flow around a rectan-gular 5:1 cylinder, which has been thoroughly investigated for architectural design. The purpose of UQ is validation of numerical simulation results with experimental data, therefore the radius of curvature of the rectangular cylinder corners and the angle of attack are considered to be random variables, which are known to contain uncertainties when wind tunnel tests are carried out. Computational Fluid Dynamics (CFD) simulations are solved by a solver that employs the Finite Element Method (FEM) for two turbulence modeling approaches of the incompressible Navier-Stokes equations: Unsteady Reynolds Averaged Navier Stokes (URANS) and the Large Eddy simulation (LES). The results of the uncertainty analysis with CFD are compared to experimental data in terms of time-averaged pressure coefficients and bulk parameters. In addition, the accuracy and efficiency of the multi-fidelity framework is demonstrated through a comparison with the results of the high-fidelity model.

CO2 지중저장에 따른 장기분지 내 단층안정성 기초해석 (Numerical Analysis of Fault Stability in Janggi Basin for Geological CO2 Storage)

  • 박정욱;김한나;이항복;박찬희;신영재
    • 터널과지하공간
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    • 제33권5호
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    • pp.399-413
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    • 2023
  • 본 연구에서는 TOUGH-FLAC 연동해석 기법을 사용하여 장기분지 유망 저장소 부지에서의 CO2 주입을 수치적으로 모델링하고, 주변 지층과 단층에 야기되는 수리-역학적 안정성을 검토하였다. 대상부지의 현장조사와 3D 지질모델을 기반으로 3년간 32,850톤의 CO2 주입을 가정하여 시뮬레이션을 수행하였다. 저류층의 투수계수에 따른 CO2 플럼의 유동 경로를 분석한 결과, 투수계수를 10-14 m2로 가정한 경우 방사형 유동을 보이며 2년 9개월 경과 시 단층에 도달하는 것으로 나타났다. 투수계수를 10-13 m2로 가정한 경우에는 저류층을 따라 서쪽 방향의 유동이 우세하게 나타났으며 단층 방향으로의 유동은 거의 발생하지 않았다. 주입공 주변의 압력 변화는 3년 동안 0.6 MPa 이하로, 지층 및 단층의 역학적 안정성에 미치는 영향은 미미한 것으로 분석되었다.

Pulsatility Index in Different Modifications of Fontan Palliation: An Echocardiographic Assessment

  • Reza Shabanian;Parvin Akbari Asbagh;Abdullah Sedaghat;Minoo Dadkhah;Zahra Esmaeeli;Aliyeh Nikdoost;Manizheh Ahani;Mitra Rahimzadeh;Alireza Dehestan;Mohammad Ali Navabi
    • Journal of Cardiovascular Imaging
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    • 제30권2호
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    • pp.99-108
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    • 2022
  • BACKGROUND: Adding pulsation to the Fontan circulation might change the fate of patients palliated by this procedure. Our aim was to compare the pulsatility index (PI) of the pulmonary artery (PA) between the various modifications of Fontan palliation. METHODS: Doppler-derived PI was measured in PA branches of a cohort of 28 patients palliated by 6 modifications of Fontan procedure. A group of normal individuals was included for comparison. RESULTS: Atriopulmonary connection (APC) group had the highest PA branches PI and statistically was close to the PI of the normal individuals (right pulmonary artery [RPA] PI of 1.58 vs. 1.63; p = 0.99 and left pulmonary artery [LPA] PI of 1.54 vs. 1.68; p = 0.46, respectively). The lowest PA branches PI was seen in the group of extracardiac total cavopulmonary connection (RPA PI of 0.62 and LPA PI of 0.65). Other 4 modifications including the extracardiac conduit with oversewn pulmonary valve, extracardiac conduit with preserved adjusted antegrade flow, extracardiac conduit from inferior vena cava onto the rudimentary right ventricle and lateral tunnel had a mean "RPA and LPA" PI of "1.19 and 1.17", "1.16 and 1.11", "1.13 and 1.11", "0.82 and 0.84", respectively. The modified Dunnett's post hoc test has shown a significant statistical decline in PI of all modifications compared to the normal individuals except for the APC group. CONCLUSIONS: Fontan palliated patients in different groups of surgical modification showed a spectrum of Doppler-derived PI with the highest amounts belong to the groups of pulsatile Fontan.

설비공학 분야의 최근 연구 동향 : 2007년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2007)

  • 한화택;신동신;최창호;이대영;김서영;권용일
    • 설비공학논문집
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    • 제20권12호
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    • pp.844-861
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    • 2008
  • The papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during the year of 2007 have been reviewed. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environments. The conclusions are as follows. (1) The research trends of fluid engineering have been surveyed as groups of general fluid flow, fluid machinery and piping, etc. New research topics include micro nano fluid, micropump and fuel cell. Traditional CFD was still popular and widely used in research and development. Studies about fans and pumps were performed in the field of fluid machinery. Characteristics of flow and fin shape optimization are studied in the field of piping system. (2) The research works on heat transfer have been reviewed in the field of heat transfer characteristics, heat exchangers, and desiccant cooling systems. The research on heat transfer characteristics includes thermal transport in pulse tubes, high temperature superconductors, ground heat exchangers, fuel cell stacks and ice slurry systems. For the heat 'exchangers, the research on pin-tube heat exchanger, plate heat exchanger, condensers and gas coolers has been cordially implemented. The research works on heat transfer augmenting tubes have been also reported. For the desiccant cooling systems, the studies on the design and operating conditions for desiccant rotors as well as performance index are noticeable. (3) In the field of refrigeration, many papers were presented on the air conditioning system using CO2 as a refrigerant. The issues on the two-stage compression, the oil selection, and the appropriate oil charge were treated. The subjects of alternative refrigerants were also studied steadily. Hydrocarbons, DME and their mixtures were considered and various heat transfer correlations were proposed. (4) Research papers have been reviewed in the field of building facilities by grouping into the researches on heat and cold sources, air conditioning and air cleaning, ventilation and fire research including tunnel ventilation, flow control of piping system, and sound research with drain system. Main focuses have been addressed to the promotion of efficient or effective use of energy, which helps to save energy and results in reduced environmental pollution and operating cost. (5) Studies were mostly focused on analyzing the indoor environment in various spaces like cars, old tombs, machine rooms, and etc. in an architectural environmental field. Moreover, subjects of various fields such as the evaluation of noise, thermal environment, indoor air quality and development of energy analysis program were researched by various methods of survey, simulation, and field experiment.

설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제27권7호
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. 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 heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were 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 thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance 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 was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

공기조화, 냉동 분야의 최근 연구 동향: 2006년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2006)

  • 한화택;신동신;최창호;이대영;김서영;권용일
    • 설비공학논문집
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    • 제20권6호
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    • pp.427-446
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    • 2008
  • A review on the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2006 has been accomplished. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environments. The conclusions are as follows. (1) The research trends of fluid engineering have been surveyed as groups of general fluid flow, fluid machinery and piping, etc. New research topics include micro heat exchanger and siphon cooling device using nano-fluid. Traditional CFD and flow visualization methods were still popular and widely used in research and development. Studies about diffusers and compressors were performed in fluid machinery. Characteristics of flow and heat transfer and piping optimization were studied in piping systems. (2) The papers on heat transfer have been categorized into heat transfer characteristics, heat exchangers, heat pipes, and two-phase heat transfer. The topics on heat transfer characteristics in general include thermal transport in a cryo-chamber, a LCD panel, a dryer, and heat generating electronics. Heat exchangers investigated include pin-tube type, plate type, ventilation air-to-air type, and heat transfer enhancing tubes. The research on a reversible loop heat pipe, the influence of NCG charging mass on heat transport capacity, and the chilling start-up characteristics in a heat pipe were reported. In two-phase heat transfer area, the studies on frost growth, ice slurry formation and liquid spray cooling were presented. The studies on the boiling of R-290 and the application of carbon nanotubes to enhance boiling were noticeable in this research area. (3) Many studies on refrigeration and air conditioning systems were presented on the practical issues of the performance and reliability enhancement. The air conditioning system with multi indoor units caught attention in several research works. The issues on the refrigerant charge and the control algorithm were treated. The systems with alternative refrigerants were also studied. Carbon dioxide, hydrocarbons and their mixtures were considered and the heat transfer correlations were proposed. (4) Due to high oil prices, energy consumption have been attentioned in mechanical building systems. Research works have been reviewed in this field by grouping into the research on heat and cold sources, air conditioning and cleaning research, ventilation and fire research including tunnel ventilation, and piping system research. The papers involve the promotion of efficient or effective use of energy, which helps to save energy and results in reduced environmental pollution and operating cost. (5) Studies on indoor air quality took a great portion in the field of building environments. Various other subjects such as indoor thermal comfort were also investigated through computer simulation, case study, and field experiment. Studies on energy include not only optimization study and economic analysis of building equipments but also usability of renewable energy in geothermal and solar systems.

완전 대정맥-폐동맥 연결수술로 전환 후의 폰탄순환장애 개선 (Improvement of Fontan Circulatory Failure after Conversion to Total Cavopulmonary Connection)

  • Han Ki Park;Gijong Yi;Suk Won Song;Sak Lee;Bum Koo Cho;Young hwan Park
    • Journal of Chest Surgery
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    • 제36권8호
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    • pp.559-565
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    • 2003
  • 완전 대정맥-폐동맥 연결(total cavopulmonary connection, TCPC)은 폰탄 순환의 혈류를 개선시킴으로써 심방폐동맥 형태의 폰탄 연결보다 우수한 결과를 가져올 수 있다. 심방페동맥연결 후 혈역학 장애를 보이는 환자들에서 TCPC로의 전환 수술은 혈역학적, 기능적 호전을 가져을 것으로 생각된다. 폰탄 순환장애가 있는 환자에서 이전의 폰탄 수술을 TCPC로의 전환술의 결과를 연구하였다. 대상 및 방법: 1979년 10월부터 2002년 6월까지 연세대학교 의과대학 부속병원에서 8명이 폰탄순환 장애로 과거의 폰탄 수술을 완전대정맥-폐동맥 연결로 전환하였다. 환자들의 심장 기형은 삼첨판 폐쇄증(n=4)과, 기타 기능성 단심실(n=4)이었다. TCPC로 전환 수술 시 평균 나이는 14.0$\pm$7.0년이었으며 (4.6~26.2세), 폰란 술식 후 대동맥-페동맥 연결로 전환한 사이의 간격의 중앙값은 7.5년(2.414.3년)이었다. 모든 환자들이 다양한 정도의 우심부전의 증상과 징후를 나타내었다. 6명의 환자가 NYHA기능적 분류의 111또는 IV에 해당되었다. 발작성 심방세동 (n=1), 청색증(n=2), 심방내 혈전(n=2)과 단백소모성 장질환(n=3)이 동반되어 나타났다. 이전의 폰탄수술은 심장외도관 (n=7)과 심방내외측통로(n=1)로 전환되었다. 결과 수술 사망은 없었다. 주요 합병증으로는 심부흉골감염(n=1), 2주 이상의 지속적인 흉막삼출(n=1), 일시적 접합부빈맥(n=1)이 있었다. 수술 후 중심정맥압은 수술 전에 비해 감소하였다(17.9$\pm$3.5 vs 14.9$\pm$l.0, p=0.049). 모든 환자를 추적 관찰하였으며, 최장 추적관찰 기간은 50.1개월(평균 30.3 $\pm$ 12.8개월)이었다. 만기 사망은 없었다. 모든 환자들이 NYHA기능분류 I또는 II에 해당되었다. 발작성 상심실성빈맥이 심방내외측통로수술로 전환받은 환자에서 발생하였다. 수술 전 단백소실성 장질환을 가지고 있던 환자 3명 중 2명에서 단백소실성 장질환이 재발하였다. 결론: 폰탄 술식 후 폰탄순환의 장애에 의한 혈행장애는 과거의 폰탄 술식을 완전 대정맥-폐동맥 연결로 전환해서 혈역학적 기능과 증상의 호전을 기대할 수 있었으며 수술 사망과 합병증의 위험은 높지 않다.

천성산 밀밭늪의 강우 유출 및 지하수위 변동 특성 (Characteristics of the Rainfall-Runoff and Groundwater Level Change at Milbot Bog located in Mt.Cheonseong)

  • 정유경;이상원;이헌호
    • 한국산림과학회지
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    • 제99권4호
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    • pp.559-567
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    • 2010
  • 본 연구는 천성산 밀밭늪 지역의 고속철 터널공사에 따른 지하수위의 변동과 강우 유출의 특성을 밝히기 위하여 2004년 7월부터 2008년 5월에 걸쳐 수행하였으며, 그 결과는 다음과 같다. 밀밭늪에서 단위 강우로 인해 발생하는 직접유출량의 발생시각은 일반 산지유역에서보다 다소 늦어지는 경향이 있었으며, 또한 강우로 인해 발생하는 유출량의 장 단기수문곡선은 대부분의 경우 강우에 대응하여 민감하게 반응하지 않았다. 연간 유출률은 2004년 0.26, 2005년 0.13, 2006년 0.16, 2007년 0.25, 2008년 0.27로 나타나 고속철 터널공사에 관계없이 매년 점진적으로 증가하였다. 이와 같이 밀밭늪에서 해마다 유출률이 증가함에 따라 향후 밀밭늪의 기능이 약화되어 점차 육화되어 갈 것으로 판단하였다. 또한 이들 각 연도의 유출률은 일반 산지유역의 유출률보다 크게 낮은 값으로 나타났으며, 4년간 평균 연간 유출률은 0.19으로 계산되었다. 단기수문곡선에서 직접유출의 감수계수는 0.89~0.97의 범위로 관측되어 일반 산지소유역의 값인 0.2~0.8보다 높게 나타났으며, 기저유출의 감수계수는 0.93~0.99의 범위로 관측되어 일반 산지 소유역의 값과 비슷하게 관측되었다. 밀밭늪의 지하수위는 강우강도에 비례하여 증감하였으며, 특히 지하수위가 정점(피크)에 도달한 후 하강 시에는 아주 완만하게 낮아지는 경향이 있었다. 또한 선행강우가 있었을 때의 지하수위의 변화는 비교적 높은 값을 유지하면서 증감하였다. 강우량이 많은 여름에 지하수위가 가장 높았으며, 겨울에는 아주 낮은 지하수위 값을 나타내었다. 연도별 평균 지하수위값은 2004년 -8.48 cm, 2005년 -14.60 cm, 2006년 -20.46 cm, 2007년 -20.11 cm, 2008년 -28.59 cm로 관측되어, 매년 평균 지하수위값이 점차 낮아지는 것으로 나타났다.

공압식 갱내충전을 위한 모형실험 연구 (A Study on the Model Test for Pneumatic Mine-Filling)

  • 양인제;신동춘;윤병식;목진호;김학성;이상은
    • 터널과지하공간
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    • 제24권6호
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    • pp.449-463
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    • 2014
  • 국내의 경우 슬러리나 페이스트 형태로 수압식 충전에 대한 연구와 다양한 폐광산 현장에 적용한 사례는 많으나, 공압식 충전에 대한 연구는 진행되지 않고 있다. 기존의 공압식 충전법은 강관의 구부러진 곳에서 충전재 유동에 의한 마모에 의해 강관의 손상이 발생한다. 이와 같은 문제점을 개선하기 위하여 새로 고안한 개량형 노즐을 이용한 공압식 충전법을 개발하였다. 본 연구에서는 접근이 가능하거나 불가능한 채굴공동을 모사하여 실험실에서 모형실험을 수행하고 그 충전효율을 평가하였다. 갱내 충전법 실험에서는 토출각의 변화, 모래의 투입량 및 입자 크기에 따라 충전효율을 분석하였으며, 지상 충전법 실험에서는 중력식, 재래식 및 개량형 충전방법의 실험으로부터 충전효율을 분석하여 개량형 공압식 충전법의 우수성을 입증하였다.