• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.209-214
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• 2006

In this study, application of groundwater thermal energy by use of riverbank filtration(RBF) system is reviewed and checked as an energy resources. Also, the cooling and heating system using RBF was developed in Chang-Won Waterwork site to examine the feasibility in real operation of the system. We estimates the roughly overall energy obtained from RBF system if the system is used in cooling and heating. The water temperature and room temperature have been monitored to evaluate the efficiency of the system and the preliminary results show that the geothermal energy obtained by RBF could be adopted in cooling and heating energy source efficiently.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.509-516
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• 2004

The measurement of abnormal change of temperature(temperature anomaly) will help determine the safety of various engineering constructions, as the measurement in body often used to diagnose one's health. Temperature anomaly can be occurred in leakage or seepage of water flow in rocks, and in ground water table etc. Grouting materials injected in fractured rocks generate heat during hardening process. The degree of temperature change is associated directly with heat flow characteristics, that is, thermal conductivity, specific heat capacity. density of the surrounding rocks and can afford to assess the grouting efficiency. However, in practice, the use of traditional temperature measuring technique composed of only one single thermal sensor has been fundamentally limited to acquire thermal data sufficient to use for that, partly due to the time-consuming measuring work, partly due to the non-consecutive quality of data. Thus, in this paper, a new concept of temperature measuring technique, what we call, thermal line sensor technique is introduced. In this, the sensors with an accuracy of $0.02^{\circ}$ are inserted at regular intervals in one line cable and addressed by a control device, which enables to fundamentally enhance the capability of data acquisition in time and space. This new technology has been demonstrated on diverse field model experiments. The results were simply meant to be illustrative of a potential to be used for various kinds of temperature measurements encountered in grouting and leakage problems.

• 생물환경조절학회지
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• 제31권4호
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• pp.300-310
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• 2022

본 실험은 펄라이트 수경재배에서 급액량이 토마토(Solanum lycopersicum L.)의 생육과 수량에 미치는 영향을 조사하기 위해 수행되었다. 급액 처리는 대조구인 I₀와 대조구보다 급액량이 각 25%, 50% 많은 I₂₅와 I₅₀로 세수준 처리하였다. 처리기간 중 대조구 I₀ 처리구는 배액이 없었다. 조사항목으로 토마토 생육특성, 수량 및 수분이용효율을 측정하였다 토마토의 초장, 엽장 및 엽폭이. I₀ 처리 가장 짧았고 I₂₅와 I₅₀ 처리에서는 통계적으로 차이가 없었다. 처리 후 111일, 132일 및 143일째에 측정한 토마토 과실의 당도, 산도 및 건물율은 관수량이 가장 적은 I₀가 관수량이 많은 I₂₅와 I₅₀ 보다 높았다. 그러나 처리 후 111일과 132일째 과실 내 수분함량은 I₀ 처리에서 가장 낮았다. 대과(>180g)의 수는 I₂₅에서 유의하게 더 많았으나 총 수확과 수는 처리 간 유의한 차이가 없었다. 과실의 평균 과중(g·plant^-1)과 총 수확량(g·plant^-1)은 I₀ 처리된 토마토에서 가장 낮았다. 수분 소비량은 처리 간 유의한 차이가 없었으나 수분이용효율은 I₀ 처리에서 가장 낮았다. 주성분 분석 결과 과실의 당도와 산도는 양의 상관관계가 있는 것으로 나타났다. 본 실험에서 토마토 생육, 과실 특성 및 수분이용효율을 토대로 얻은 결과는 I₂₅가 토마토 펄라이트 수경재배에서 다른 처리 보다 적절한 급액량임을 보여준다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.29-32
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• 2005

In this study, the experiment was carried out to investigate and analyze the strenth properties and flowability of ultra-high strength concrete accroding to types of mineral admixtures. The main experimental variables were water/binder ratio 25.0, 27.5 and 30.0$\%$, water content 155, 160, 165, and 170kg/$m^{3}$ and mineral admixtures such as fly ash, silica fume and meta kaolin. According to the test results, the principle conclusions are summarized as follows. 1) In case of using admixtures, superplasticizer amount need more than plain concrete. 2) According to kinds of admixtures, the viscosity of concrete show much difference. 3) The compressive strength of concrete that use admixtures becomes low in early-age strength, but appeared by higher than plain concrete in long-term strength. 4) Meta kaolin is excellent in side but has viscosity enlargement efficiency a little. But, problem estimates that is not to make design strength 600 and 700kgf/$cm^{2}$ if use mixing condition with water-binder ratio properly.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.261-264
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• 2004

In this study, the experiment was carried out to investigate and analyze the strenth properties and flowability of ultra-high strength concrete accroding to types of mineral admixtures and cements. The main experimental variables were water/binder ratio $25.0\%$, water content $160kg/m^3$ and mineral admixtures such as fly ash, silica fume and meta kaolin. According to the test results, the principle conclusions are summarized as follows 1) In case of using admixtures, superplasticizer amount need more than plain concrete. 2) According to kinds of admixtures and cements, the viscosity of concrete show much difference. 3) The autogeneous shrinkage of ultra-high strength concrete is profitable that use admixture, and heat of hydration is desirable that apply considering countermeasure enough in the advance. 4) Meta kaolin is excellent in side but has viscosity enlargement efficiency a little. But, problem estimates that is not to make design strength to and $70N/mm^2$ if use mixing condition with water-binder ratio properly.

• 물과 미래
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• 제28권1호
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• pp.145-152
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• 1995

본 연구는 수리실험을 통하여 전기와 같은 외부적인 에너지의 사용없이 물을 양수시킬 수 있는 Cherepnov 양수장치에 대하여 연구하였다. 이 양수장치는 물 자체가 갖고 있는 위치에너지에 의하여 작동되며, 양수장치의 구조는 1개의 상단 개구부를 갖는 수조와 2개의 밀폐된 수조가 상호 연결된 형태로 이루워져 있다. 양수장치의 거동과 작동특성을 조사 연구하기 위하여 수조내의 수위와 압력변화를 측정하였다. 양수장치에 유입되는 유입량, 수조와 연결파이프의 크기, 수조의 상대적 위치가 양수장치의 작동에 미치는 영향등을 분석하였다. 본 실험을 통하여 양수장치의 효율을 높이고, 작동주기를 짧게하며, 양수되는 송수량을 늘리는 인자가 규명되었다.

• 한국산업보건학회지
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• 제20권2호
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• pp.131-138
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• 2010

This technical report was developed to suggest the guideline to assess the safe use and handling metalworking fluids (MWFs) in machining operation. The basis of this method developed in this study was based on self assessment procedure recommended by Organization Resources Counselors (ORC) of the United States (US). In addition, various MWF management elements obtained from the review on various articles, reports and author's experience regarding MWF were newly added to the evaluation guideline. A total of four areas were finally selected in order to control exposure to MWF used in machining operations. They are all related to the presence and efficiency of the control measures, exposure assessment, management on tank and sump, and safe treatment of chips and metal fines generated during machining operations. Each area is consisted of several related elements. Several evaluation areas and elements used in this study could be revised, replaced, added and deleted according to the process environment, evaluation objectives and evaluator's (manager) criteria etc. This evaluation guide manual could be used for safe management of MWF in metalworking operation. In addition, industrial hygienists can use this evaluation method for auditing and evaluating the management status on MWF.

• Advances in Energy Research
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• 제5권3호
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• pp.207-217
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• 2017

Energy consumption in agriculture is responsible for greenhouse gas emission but it can be reduced after efficient utilization of energy inputs. Therefore, the present study aims for the estimation of energy efficiency and extent of greenhouse gas reduction after benchmarking of inefficient farms in off-season tomato in Punjab province of Pakistan. Primary data were collected from 70 farmers with simple random sampling. By using data envelopment analysis, the average value of technical, pure technical and scale efficiency was 0.80, 0.92 and 0.87, respectively while increasing, constant and decreasing return to scale was observed in 33, 26 and 11 farmers, respectively. Total input energy was reduced by $12,688.91MJ\;ha^{-1}$ (13.89%) if inefficient farms used the energy inputs according to recommendations or benchmarking. A major portion of energy saving comes from fertilizers (68.79%) followed by diesel (15.70%), chemicals (5.91%), machinery (4.37%) and water (4.00%). Total greenhouse gases reduction was $499.17kg\;CO_2\;eq.ha^{-1}$ (14.57%) as a result of improvement in energy efficiency or benchmarking of inefficient farms. Agricultural extension staff should visit the vegetable farms on regular basis and give necessary information about efficient utilization of energy inputs. The government should create awareness about the optimum use of input through seminars and pamphlets.

• Journal of Biosystems Engineering
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• 제38권4호
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• pp.306-311
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• 2013

Purpose: With the ever-rising energy prices, thermal energy heavily consuming facilities of the agricultural sector such as commercialized greenhouses and large-scale Rice Processing Complexes (RPCs) need to cut down their energy cost if they must run profitable businesses continually. One possible way to reduce their energy cost is to utilize combustible agricultural by-products or low-price oil instead of light oil as the fuel for their boiler systems. This study aims to analyze the heavy oil combustion characteristics of a newly developed hot water boiler system that can use both rice husk and heavy oil as its fuel convertibly. Methods: Heavy oil combustion experiments were conducted in this study employing four fuel feed rates (7.6, 8.5, 9.5, 11.4 $l/h$) at a combustion furnace vacuum pressure of 500 Pa and with four combustion furnace vacuum pressures (375, 500, 625, 750 Pa) at fuel feed rates of 9.5 and 11.4 $l/h$. Temperatures at five locations inside the combustion furnace and 20 additional locations throughout the whole hot water boiler system were measured to ascertain the combustion characteristics of the heavy oil. From the temperature measurement data, the thermal efficiency of the system was calculated. Flue gas smoke density and concentrations of air-polluting components in the flue gas were also measured by a gas analyzer. Results: As the fuel feed rate or combustion furnace vacuum pressure increased, the average temperature in the combustion furnace decreased but the thermal efficiency of the system showed no distinctive change. On the other hand, the thermal efficiency of the system was inversely proportionally to the vacuum level in the furnace. For all experimental conditions, the thermal efficiency remained in the range of 80.1-89.6%. The CO concentration in the flue gas was negligibly low. The NO and $SO_2$ concentration as well as the smoke density met the legal requirements. Conclusions: Considering the combustion temperature characteristics, thermal efficiency, and flue gas composition, the optimal combustion condition of the system seemed to be either the fuel feed rate of 9.5 $l/h$ with a combustion furnace vacuum pressure of 375 Pa or a fuel feed rate of 11.4 $l/h$ with a furnace vacuum pressure between 500 Pa and 625 Pa.

• 한국물환경학회지
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• 제21권1호
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• pp.84-91
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• 2005

$TiO_2-catalyst$ suspensions work efficiently in Photocatalytic oxidation (PCO) for wastewater treatment. Nevertheless, once photocatalysis is completed, separation of the catalyst from solution becomes the main problem. The PCO of Cu(II)-EDTA was studied to determine the reusability of the titanium dioxide catalyst. Aqueous solutions of $10^{-4}M$ Cu(II)-EDTA were treated using illuminated $TiO_2$ particles at pH 6 in a circulating reactor. $TiO_2$ was reused in PCO system for treatment of Cu(II)-EDTA comparing two procedures: reuse of water and $TiO_2$ and reuse of the entire suspension after PCO of Cu(II)-EDTA. The results are as follows; (i) Photocatalytic efficiency worsens with successive runs when catalyst and water are reused without separation and filtration, whereas, when $TiO_2$ is separated from water, the reused $TiO_2$ is not deactivated. (ii) The $TiO_2$ mean recovery (%) with reused $TiO_2$ was 86.4%(1.73g/L). Although the mean initial degradation rate of Cu(II)-EDTA and Cu(II) was lower than that using fresh $TiO_2$, there was no significant change in the rate during the course of the three-trial experiment. It is suggested that Cu(II)-EDTA could be effectively treated using an recycling procedure of PCO and catalyst recovery. (iii) However, without $TiO_2$ separation, the loss of efficiency of the PCO in the use of water and $TiO_2$ due to Cu(II), DOC remained from previous degradation and Cu(II)-EDTA added to the same suspension was observed after 2 trials, and resulted in the inhibition of the Cu(II)-EDTA, Cu(II) and DOC destruction.