• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.31-31
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• 1997

우수한 비강성과 비강도를 지닌 복합재료를 이용한 자동차용 추진축(Propeller Shaft)의 사용은 자동차의 구조정량화, 소음/진동 감소, 승차감 향상 측면에서 개선된 효과를 기대할 수 있다. 본 연구에서는 탄소섬유/에폭시 필라멘트 와인딩(Filament Winding) 공빔을 적용한 복합재료 튜브와 금속재 플랜지 그리고 유니버셜 조인트로 구성된 상용 차의 추진축 개발과정 중 축의 진동특성에 대한 적합한 형상과 물성을 찾기 위해 유한요소법을 적용한 자유진동 해석과 FFT 해석장비를 이용한 진동실험 그리고 축을 운용속도까지 회전시켜 공진(Resonance) 현상 발생 유무를 소음량의 측정으로 판단하는 시험이 수행되었다. 그 결과 요구조건에 적합한 진동특성을 나타내는 추진축의 형상을 결정할 수 있었다.

• Annual Conference of KIPS
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• 2011.11a
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• pp.948-950
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• 2011

현재 많은 국가들이 자동차 업계 중심으로 사업 모델을 진행하고 있고 그중에서 M2M과 관련하여 지능형 자동차에 대해 많은 관심과 투자가 예상되고 있는데 차량 안전 운행, 교통 분야 공공 서비스, 교통 신호 확장, 차량 진단, 보안의 문제점 해결 여러 가지의 서비스가 요구되고 있다. 여기서 차량 내 졸음방지를 위한 무선제어 시스템과 졸음 방지로 인하여 교통사고의 안전과 사고율을 낮추고자 졸음 운전차량이 발생시 주변 차량에 경고 또는 온도와 이산화 탄소량을 측정하여 창문을 개방하여 운전자에게 졸음 운전으로 인한 사고율을 낮추는 시스템을 제안 한다.

• Fire Science and Engineering
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• v.23 no.5
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• pp.103-109
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• 2009

In this study, fire simulations on the under-ventilated compartment fires have been conducted using the Fire Dynamics Simulator (FDS Ver. 5.2) and its prediction performance on the thermal and combustion chemical characteristics has been discussed. The temperature and chemical species concentrations in the upper layer of methane, heptane, and toluene fires located in a 2/5 scale compartment based on the ISO-9705 standard room are predicted and compared with the previously published experimental data. The results showed that the FDS simulations reproduced well the temperature of the ceiling and the mixture fraction in the upper layer under the well-ventilation conditions. For the under-ventilated fires, which were taken place due to the insufficient oxygen entrainment, the prediction by the FDS significantly under-estimated the production of carbon monoxide and soot compared to the experimental data.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.287-294
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• 1994

PAN-based carbon fiber roving and fabric were heat treated at the temperature of $2170^{\circ}C$. Using non-heat treated and heat treated fabric, greenbodies of CFRP and GFRP were manufactured in the Autoclave. After the analysis of heat treated and non-heat treated carbon fiber roving and two types of greenbodies, the variations of physical and mechanical properties of carbon fibers and greenbodies with heat treatment were studied. Observing the cross-section of carbon fiber with SEM, we knew the diameter of carbon fiber was decreased from 6.8gm to 6.4p1. The results of TGA showed that the oxidation resistence was enhanced after heat treatment. The tensile strength of carbon fiber was decreased from (3.11$\pm 0.32)\times 10^3$ MPa to (1.87$\pm 0.26)\times 10^3$MPa, but tensile modulus was increased from (1.94$\pm 0.06)\times 10^5$ MPa to (2.02$\pm 0.11)\times 10^5$MPa after heat treatment. The interlaminar shear strengths of CFRP and GFRP were 148.8$\pm$1.6Mpa and 82.2$\pm$1.1Mpa, respectively. Torch test showed that CFRP was abraded smoothly but GFRP was delaminated.

• Clean Technology
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• v.19 no.4
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• pp.416-422
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• 2013

In environmental friendly aspects, the synthesis of glycerol carbonate from glycerol using carbon monoxide and oxygen gases which were produced in petrochemical plants was studied. The oxidative carbonylation of glycerol under batch reaction system was performed on parameter conditions such as effect of various metals (Cu, Pd, Fe, Sn, Zn, Cr), oxidizing agents, mole ratio of carbon monoxide to oxygen, catalyst amount, solvent types, reaction temperature and time and dehydrating agents. In particular copper chloride catalysts showed the excellent activities, and the glycerol carbonate yields over CuCl and $CuCl_2$ catalysts were the maximum of 44% and 64%, respectively at the following reaction conditions: solvent as nitrobenzene, mole ratio of 1:3:0.15 (glycerol:carbon monoxide:catalyst), mole ratio of 2:1 (carbon monoxide:oxygen), the total pressure of 30 bar at 413 K for 4 hr. It was found that reactivity were significantly different depending on the oxidation number of Cu catalysts, and oxygen plays an important role as oxidizing agents in producing H2O during oxidation reaction after carbonylation of glycerol.

• Journal of the Korean Institute of Gas
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• v.25 no.3
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• pp.27-38
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• 2021

We devised the system to automatically shutdown the boiler and to fundamentally block the harmful gases, including carbon monoxide, into the indoor when the exhaust system swerves: (1) The discharge pressure of the exhaust gas decreases when the exhaust pipe is disconnected. The monitoring system of the exhaust pipe is implemented by measuring the output voltage of APS(Air Pressure Sensor) installed to control the amount of combustion air. (2) The operating software was modified so that when the system recognizes the fault condition of a flue pipe, the boiler control unit displays the fault status on the indoor regulator while shutting down the boiler. In accordance with the ventilation facility standards in the "Rules for Building Equipment Standards" by the Ministry of Land, Infrastructure and Transport, experiments were conducted to ventilate indoor air. When carbon monoxide leaked in worst-case scenario, it was possible to prevent poisoning accidents. However, since 2013, the number of indoor air exchange times has been mitigated from 0.7 to 0.5 times per hour. We observed the concentration exceeding TWA 30 ppm occasionally and thus recommend to reinforce this criterion. In conclusion, if the flue pipe fault detection and the indoor air ventilation system are introduced, carbon monoxide poisoning accidents are expected to decrease significantly. Also when the manufacturing and inspection steps, the correct installation and repair are supplemented with the user's attention in missing flue, it will be served to prevent human casualties from carbon monoxide poisoning.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.208-216
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• 2022

Surface morphology and adsorption characteristics of black and white charcoals prepared from Korean traditional kiln were quantitatively analyzed. TGA and elemental analysis of charcoals were different from produced kiln, and thermal degradation temperature and carbon content of white charcoals were apparently higher than those of black charcoals. Surface morphology shows the activation progressed through the longitudinal direction of woods and new micropores were developed to radial direction on the surface of macropores as the furthermore activation resulting in the pore connection. BET adsorption isotherms show that there are low-pressure hysteresis due to the no desorption of adsorbates, which resulted in unique Type of charcoals overlapping Type I and Type IV. Such a low-pressure hysteresis is occurred from expansion of adsorbates, which were embedded in the micropore entrances and did not get out during the desorption run. The characteristics of charcoals such as specific surface area and pore size distribution did not show correct values depending on not only produced company but also sampling sites of one piece of charcoal. Therefore, it is not easy to suggest the quantitative characteristics of charcoals prepared from Korean traditional kiln. On the other hand, preparation the quality standard of charcoal is necessary for their special uses such as adsorbent.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.550-556
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• 2022

The performance of enzymatic fuel cells that convert chemical energy contained in various organic molecules such as sugar, alcohol, organic acids, and amino acids into electrical energy is greatly affected by the cathode as well as the anode. This study aimed to develop a laccase-based cathode with high performance. An enzyme composite composed of an laccase, redox mediator, and carbon nanotubes was immobilized on the surface of electrode in multiple layers, and the effect of the number of layers and the presence or absence of carbon nanotubes on electrode performance was investigated. As the number of layers of the enzyme-mediator (Lac-(PVI-Os-dCl)) on the electrode surface increased, the amount of reduction current generated at the electrode increased. The enzyme-carbon nanotube-mediator composite electrode (Lac-SWCNTs-(PVI-Os-dCl)) generated a current 1.7 times greater than that of the Lac-(PVI-Os-dCl). It was found that the largest amount of current (10.1±0.1 µA) was generated in the electrode composed of two layers of Lac-(PVI-Os-dCl) and two layers of Lac-SWCNTs-(PVI-Os-dCl) in the evaluation of electrodes with different ratio of Lac-SWCNTs-(PVI-Os-dCl) and Lac-(PVI-Os-dCl). The maximum power density of the cell using the cathode composed of a single layer of Lac-(PVI-Os-dCl) and the cell using the optimized cathode were 0.46±0.05 and 1.23±0.04 µW/cm², respectively. In this study, it was demonstrated that the performance of cathode and the enzymatic fuel cell using the same can be improved by optimizing the layers of composites composed of laccase, redox mediator, and carbon nanotubes on the electrode surface.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.2
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• pp.55-60
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• 2022

In this study, a heat treatment experiment was conducted to select a new melt composition that can easily control the unintentionally doped nitrogen (N-UID) without degrading the SiC single crystal quality during TSSG process. The experiment was carried out for about 2 hours at a temperature of 1900℃ under Ar atmosphere. The used melt composition is based on either Si-Ti 10 at% or Si-Cr 30 at%, and also Co or Sc transition metals, which are effective for carbon solubility, were added at 3 at%, respectively. After the experiment, the crucible was cross-sectionally cut, and evaluated the Si-C reaction layer on the crucible-melt interface. As a result, with Sc addition, Si-C reaction layers uniformly occurred with a Si-infiltrated layer (~550 ㎛) and a SiC interlayer (~23 ㎛). This result represented that the addition of Sc is an effective transition metal with high carbon solubility and can feed carbon sources into the melt homogeneously. In addition, Sc is well known to have low reactivity energy with nitrogen compared to other transition metals. Therefore, we expect that both growth rate and Nitrogen UID can be controlled by Si-Sc based melt in the TSSG process.

• Korean Journal of Construction Engineering and Management
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• v.24 no.6
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• pp.45-52
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• 2023

Recently, as climate change caused by greenhouse gases is intensifying, the international community has committed to reduce greenhouse gas emissions. The purpose of this study is to present the methodology and major considerations for investment judgment. Two actual cases of overseas projects were selected as study subjects. As an analysis method, the major risk factors were defined as a probability distribution, and the NPV was stochastically estimated using the Monte Carlo simulation method. In addition, assuming a policy change, the range of NPV change was analyzed. As a result, the average NPV of project A was lowered by 19%, and the probability of showing a negative NPV was 12.2%. The average value of project B was lowered by 12.5%. Considering the policy change, project A can obtain economic benefits only when it obtains 72.9% or more of the total amount of carbon credits generated, and project B is economically feasible when it acquires 49.5% or more. As a result, the average value of project A is lower than the net present value under basic assumptions, so caution is needed in investment decisions depending on changes in major risk factors. Additionally, considering policy changes, the carbon credit distribution ratio should be differentially applied depending on the project size, and this was presented as a specific figure.