• Journal of Biosystems Engineering
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• v.31 no.1 s.114
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• pp.9-15
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• 2006

Draft control is key technique in plow control system for automation of implement control system. To make the consistent draft force is an essential factor for preventing the reduction of working efficiency by tractor's slip and also improving the working efficiency. Therefore, the purpose of this study is to develop the draft sensor for draft control of plow and evaluate the usability of the algorithm of draft control system using proportional control valve. The developed draft control system could extract the draft force very well regardless of draft condition, change of setting draft force and response time in the response characteristic test. The maximum draft force at 3-Point linkage was 10,000 N and the deviation of the control system was 125.8 N in steady state condition. The developed control system worked very well with regard to the change of draft force in field and even in soil condition with soil reaction. The results of experiment showed the characteristics of response was sufficient to be used as the implement draft control system for tractor using proportional valve.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.1
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• pp.19-25
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• 2018

The objectives of this study were to evaluate the removal characteristics of total nitrogen, the influence factor of denitrification and the optimum operating condition in the pigment wastewater treatment using PAC-A/O process. The operating conditions of PAC-A/O process were mean BOD volumetric loading $0.86kgBOD/m^3/day$, mean F/M ratio 0.072~0.13 kgBOD/kgMLVSS/day and mean C/N ratio 3.47, respectively. The conditions of anoxic process in the field plant test were mean pH 8.3~8.7 and mean temperature $34.1{\sim}44.0^{\circ}C$. The ORP bending point knee was eventually appeared in the ORP -107 mV and $NO_3{^-}-N$ removal efficiency was increased according to the ORP decrease. In the ORP -107 mV below condition, the removal efficiency of T-N and $NO_3{^-}-N$ was 92.3~95.0% and 98.5~99.7%. Denitrification rate was calculated to be 1.581~1.791 mg $NO_3{^-}-N/gMLSS/hr$. The experimental results showed that the ORP control in the PAC-A/O process could be an effective method for treatment of pigment wastewater.

• Korean Journal of Materials Research
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• v.13 no.5
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• pp.313-316
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• 2003

The new epitaxial base cell as a high efficiency Si solar cell was fabricated and the effect of buried contact on the cell characteristics was investigated. In our experiments, the cell with buried contact showed the open circuit voltage of 0.62 V, the short circuit current of 40 mA, the fill factor of 0.7, and the efficiency of 10% under the incident light of AM-1 100 ㎽/$\textrm{cm}^2$. The insertion of buried contact in the epitaxial base structure brought the fabricated cell to the efficiency improvement of about 33%. The cell proposed in this paper has the structural superiority in the fabrication of high efficiency solar cell due to the carrier drift transport in the optical absorption region and the formation of back surface field by $p^{－}$ $p^{+}$ epitaxial base, and the reduction of emitter series resistance by n＋ buried contact.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.286-293
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• 2005

In soft ground the settlement criterion usually governs. Therefore, it is very important not only reasonable assessment of the allowable bearing capacity of the soil but also reasonable assessment of settlement. In the previous studies by many other researchers, load concentration ratio and settlement reduction factor are usually proposed for estimating the settlement of granular compaction piles. In the previous studies, the reinforced ground with granular compaction piles is simplified as composite ground and the analysis is performed with in the basis of this assumption. However, the lateral deformation of granular compaction pile could not be considered and only the relative vertical strength between pile and soils could be considered in the analysis. In this study, a method adapting the Tresca failure criterion is proposed for calculating settlement of granular compaction pile. Proposed method can be considered the strength of pile material, pile diameter, installing distance of pile and the deformation behavior of vertical and horizontal directions of pile. In the presented study, large-scale field load test is performed and the results are described. Also, predictions of settlements from the proposed method are compared with the results of the load test. In addition, a series of parametric study is performed and the design parameters are analyzed.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.149-154
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• 2007

This study examines the effect of acoustic excitation using forced coaxial air on the flame characteristics of turbulent hydrogen nonpremixed flames. A resonance frequency was selected to acoustically excite the coaxial air jet due to its ability to effectively amplify the acoustic amplitude and reduce flame length and NOx emissions. Acoustic excitation causes the flame length to decrease by 15 % and consequently, a 25 % reduction in EINOx is achieved, compared to a flame without acoustic excitation. Moreover, acoustic excitation induces periodical fluctuation of the coaxial air velocity, thus resulting in slight fluctuation of the fuel velocity. From phase-lock PIV and OH PLIF measurement, the local flow properties at the flame surface were investigated under acoustic forcing. During flame-vortex interaction in the near field region, the entrainment velocity and the flame surface area increased locally near the vortex. This increase in flame surface area and entrainment velocity is believed to be a crucial factor in reducing flame length and NOx emission in coaxial jet flames with acoustic excitation. Local flame extinction occurred frequently when subjected to an excessive strain rate, indicating that intense mass transfer of fuel and air occurs radially inward at the flame surface.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.593-596
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• 2006

Productivity is the most important factor directly link to success and failure of a work in construction industry. To evaluate this productivity, simulation technique is verified as a fine inspection tool through various experiment reports. On this project, we have proved the part of improvement on productivity using this simulation technique, applied to this field sites. We have used CYCLONE, which is the most appropriate simulation technique on this project. As a result of Simulation analysis, it has been confirmed that the productivity was enhanced due to the advancement of equipment, hence the reduction of air is being effected.

• Fire Science and Engineering
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• v.21 no.1 s.65
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• pp.51-59
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• 2007

The purpose of this study is analyzing the fire behavior according to the fire load for G underground shopping mall located in Daegu city. when predict fire behavior, fire load and ventilation coefficient are important factor who dominate fire temperature or fire continuance time. Therefore, size of unit room, opening size and inflammable investigated on the field. Fire load calculated using unit calorific value by each material of inflammable that investigate. And reduction model experimented fire load about 6 models with variable. Fire behavior analyzed by heat flows of inside space that temperature rise and temperature change by time of fire source.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.77-88
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• 1997

The heat rejection to coolant is a dominant factor for building vehicle cooling system such as radiator and cooling fan. Since the vehicle cooling system also has effects on fuel consumption and noise, the study of heat rejection to coolant has been emphasized. However, the study on heat rejection to coolant has been mainly focused on the field that related to the characteristics of combustion and localized heat loss. It is no much of use in design for the entire cooling system because it is focused on such a specific point. In this work, the heat rejection rate to coolant for four different engines are obtained to derive a simple heat transfer empirical formula that can be applied to the engine cooling system design, and it is compared with the other studies. Also, to observe effects of engine operation factors and heat transfer factors on coolant, we measured the metal temperature and the heat rejection rate. The heat rejection to coolant does not depend significantly upon the coolant flowrate, but mainly upon the amount of air fuel mixture and the air fuel ratio as long as the composition of coolant does not change. The reduction of heat rejection to coolant did not effectively improve the fuel consumption, but was mostly converted to raise the exhaust gas temperature and the oil temperature.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.45-50
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• 2011

The efficiency of solar cell was about 4[%] in initial stage of photovoltaic industry, but it has quite a lot of efficiency through technology advances. Today, the efficiency of c-Si solar cells is about 17 to 19[%] and the efficiency of PV modules is about 14 to 15 [%]. We called that electrical losses occurred in the Conversion of solar cells to PV modules are CTM loss(Cell To Module loss), the CTM loss typically has a value of about3~5[%]. The more efficiency of solar cell increase, differences are larger because the efficiency decrease owing to physical or technical problems occurred in the Conversion of solar cells to PV modules. In this study, the power loss factors occurred in the Conversion of solar cells to PV modules are analyzed and it is proposed that how to reduce losses of the PV module. The types of power loss factor are (1)losses of front glass and encapsulant(generally EVA sheet), (2)losses by sorting miss, (3)losses by interconnection, (4)losses by the field aging of PV modules. In further study, experimental and evaluation will be conducted to make demonstrate for proposed solutions.

• Journal of Environmental Science International
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• v.15 no.10
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• pp.913-918
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• 2006

Despite the wide distribution of air pollutants, the concentrations of indoor air pollutants may be the dominant risk factor in personal exposure due to the fact that most people spend an average of 80% of their time in enclosed buildings. Researches for improvement of indoor air quality have been developed such as installation of air cleaning device, ventilation system, titanium dioxide$(TiO_2)$ coating and so on. However, it is difficult to evaluate the magnitude of improvement of indoor air quality in field study because indoor air quality can be affected by source generation, outdoor air level, ventilation, decay by reaction, temperature, humidity, mixing condition and so on. In this study, evaluation of reduction of formaldehyde and nitrogen dioxide emission rate in indoor environments by $TiO_2$ coating material was carried out using mass balance model in indoor environment. we proposed the evaluation method of magnitude of improvement in indoor air quality, considering outdoor level and ventilation. Since simple indoor concentration measurements could not properly evaluate the indoor air quality, outdoor level and ventilation should be considered when evaluate the indoor net quality.