• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.21-28
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• 2009

A grouting method has been widely used in construction of large-scale structure to reduce permeability and reinforce the ground. If cement and grout material were not mixed well in the injection tip equipment, an opposite flow and interception state of the chemical grouting can occur. McG (Multi-mixing counterflow prevented Grouting, McG) method installed a special grouting device to allow better mixing of the grouting material(above fineness $6,000cm^2/g$) and prevent backward flow. The block of nozzle also diversify powder rate of cement. YSS (Youngil Special Silicate, YSS) that lowers $Na_2O$ and thereby increases durability was developed by gel-forming reaction material. The seepage state and unconfined compressive strength of the injection material using the special injection tip equipment was tested in this study. The results of this study showed that the uniaxial compressive strength, permeability, N-value, TCR and RQD were improved by this method. Engineering characteristics obtained by the special injection tip method will be compared with those by the other method through various field tests from now on.

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.421-431
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• 2007

The main purpose of this study is to develop a sprayed FRP repair and strengthening method, which is a new technique for strengthening the existing concrete structures by mixing one of the carbon or glass chopped fibers and one of the epoxy or vinyl ester resins with high-speed compressed air in open air and randomly spraying the mixture onto the concrete surface. At present, the sprayed FRP repair and strengthening method using the epoxy resin has not been fully discussed. In order to investigate the material property of the sprayed FRP, this study carried out tensile tests of the material specimens, which were changed with the combinations of various variables including the length of chopped fiber and the mixture ratio of chopped fiber and resin. These variables were set to have the equal material strength, compared with that of one layer of the FRP sheet. As a result, the optimal length of glass and carbon chopped fibers was fumed out to be 38 mm, and the optimal mixture ratio between chopped fiber and resin was also turned out to be 1 : 2 from each variable. And also, the thickness of the sprayed FRP to have the equal strength to one layer of the FRP sheet was finally calculated. In is study, a series of experiments were carried out to evaluate the strengthening effects of flexural beams, shear beams and damaged beams strengthened with the sprayed FRP method, respectively. The results revealed that the strengthening effects of the flexural and shear specimens were reasonably similar to those of the FRP sheet, and the developed Sprayed FRP technique is able to be used as a strengthening scheme of existing RC building.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1045-1050
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• 2014

$N_2O$(Nitrous Oxide) is known as the third major GHG(Green House Gas) following $CO_2$(Carbon Oxide) and $CH_4$(Methane). The GWP(Global Warming Potential) factor of $N_2O$ is 310 times as large as that of $CO_2$ because $N_2O$ in the atmosphere is very stable, and it becomes a source of secondary contamination after photo-degradation in the stratosphere. Investigation on the cause of the $N_2O$ formation have been continuously reported by several researchers on power sources with continuous combustion form, such as a boiler. However, in the diesel engine, research on $N_2O$ generation which has effected from fuel components has not been conducted. Therefore, in this research, author has investigated about $N_2O$ emission rates which was changed by nitrogen and sulfur concentration in fuel on the diesel engine. The test engine was a 4-stroke direct injection diesel engine with maximum output of 12 kW at 2600rpm, and operating condition of that was set up at a 75% load. Nitrogen and sulfur concentrations in fuel were raised by using six additives : nitrogen additives were Pyridine, Indole, Quinoline, Pyrrol and Propionitrile and sulfur additive was Di-tert-butyl-disulfide. In conclusion, diesel fuels containing nitrogen elements less than 0.5% did not affect $N_2O$ emissions in the all concentrations and kinds of the additive agent in the fuel. However, increasing of the sulfur additive in fuel increased $N_2O$ emission in exhaust gas.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.413-418
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• 2016

Recently, a mega project such as Korea-China or Korea-Japan undersea tunnel project has been emerged for detail discussion and the interest in undersea tunnel is on the rise. More severe damage by train fire is expected in undersea tunnel comparing to ground tunnel and thus the study on more efficient fire extinguishing system, besides existing disaster prevention design is underway. To that end, a full-scale fire tests using CAF fire extinguishing system which has been developed by modifying traditional foam fire extinguishing system for fire suppression at rescue station in timely manner were conducted over 7 times. The test was conducted after setting the rescue station in virtual tunnel with a car of KTX. As a result of using compressed air foam directly to the fire source, 30 liter of Heptane combustibles was extinguished within 1 minutes. Applicability of compressed air foam to train fire at rescue station in undersea tunnel was has been proven and further study is considered required while changing the nozzle angle and location so as to achieve quick and easy extinguishing goal, making use of the advantage of CAF, as well as to reduce the fire water and chemicals required.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1375-1381
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• 2011

Combustion processes in an optically-accessible single-cylinder heavy-duty diesel engine equipped with a highpressure common-rail injection system were investigated for JP-8 and diesel. Direct imaging and two-color thermometry were employed to verify the emission trend for both fuels. The combustion process was characterized by image analysis with focus on luminosity. The results of two-color thermometry were analyzed on the basis of the flame temperature and KL factor distribution. Analysis of the combustion process by direct imaging showed that the ignition delay was longer for JP-8 than for diesel, while the flame was extinguished rapidly. Analysis of the flame luminosity showed that the combustion intensity was higher for diesel and that the flame lasted for a longer duration in this case. Two-color thermometry results showed that the high-temperature region extended over a large area during JP-8 combustion, implying the formation of a large amount of $NO_x$. In addition, the KL factor showed low level over a large area and relatively homogeneous in the case of JP-8 combustion, which implied that less smoke was produced when using this fuel.

• MALSORI
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• no.31_32
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• pp.173-193
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• 1996

불어의 "묵음 e(e muet)"에 대한 정의를 내리기는 매우 까다롭다. 불어에서 "e"가 "묵음 e(e muet)"로 불리우는 이유는 "e"가 흔히 탈락되기 때문이다. 현재 "e muet"는 다음 발화체에서 볼 수 있듯이 열린음절에서만 나타난다. "Je/le/re/de/man/de/ce/re/por/ta/ge/." [omitted](나는 그 리포트를 다시 요구한다. : 이 경우 실제 발화시 schwa 삭제 규칙이 적용된다.) 둘째, 접두사에 나타나는 "e muet"는 s의 중자음 앞에서 s가 유성음, [z]로 발음되는 것을 막기 위해 쓰인다. "ressembler[omitted](닮다); ressentir[omitted](느끼다)" 같은 경우, 셋째, 몇몇 낱말의 경우 고어의 철자가 약화되어 "e muet"로 발음이 되고 있다. "monsieur[$m{\partial}sj{\emptyset}$](미스터), faisan[$f{\partial}z{\tilde{a}}$](꿩), faisait[$f{\partial}z{\varepsilon}$]("하다"동사의 3인칭 단수 반과거형)"등. 또 과거 문법학자들은 이를 "여성형의 E"로 불렀는데, 이는 형태론적으로 낱말의 여성형을 남성형과 구분짓기 위해 사용되고 있기 때문이기도 하다. 예를 들어, "$aim{\acute{e}}-aim{\acute{e}}e$"(발음은 둘 다 [${\varepsilon}me$]로 동일하다 : 사랑받다)의 경우. 현대불어의 구어체어서 "e muet"는 어말자음을 발음하기 위해 쓰이고 있다. 예를 들어, "pote[pot](단짝)-pot[po](항아리)". 이러한 "e muet"는 발음상으로 지역적, 개인적 및 문맥적 상황에 따라 그 음색 자체가 매우 불안정하며 여러 가지 음가(열린 ${\ae}$ 또는 닫힌 ${\O}$)로 나타난다. 예를 들어 "seul[$s{\ae}l$](홀로), ceux[$s{\O}$](이것들)"에서와 같이 발음되며, 또한 원칙적으로 schwa, [${\partial}$]로 발음이 되는 "Je[$\Im\partial$]"와 "le[$l{\partial}$]"의 경우, Paris 지역에서는 "Je sais[${\Im}{\ae}{\;}s{\Im}$](나는 안다); Prends-le[$pr{\tilde{a}}{\;}l{\ae}$](그것을 집어라)"로 발음을 하는 한편, 프랑스 북부 지방세서는 동일한 발화체를 [${\ae}$]대신에 [${\o}$]로 발음한다. 실제로 언어학적 측면에서 고려되는 "e muet"는 schwa로 나타나는 "Je[$\Im\partial$]"와 "le[$l{\partial}$]"의 경우인데, 불어 음운론에서는 schwa에 의해 대립되는 낱말짝이 없기 때문에 schwa를 음소로 인정할 것인가에 대해 논란이 있다. 그러나 불어에서 schwark 음운론적 역할을 한다는 사실은 다음과 같은 예에서 찾아 볼 수 있다. 첫째, 발음상으로 동사의 변화형에서 "porte[$p{\jmath}rte$](들다: 현재형), porte[$p{\jmath}rte$](과거분사형), porta[$p{\jmath}rte$](단순과거형)"등이 대립되며, 이휘 "Porto[$p{\jmath}rte$](포르토)"와도 대립된다. 둘째, 어휘적 대립 "le haut[$l{\partial}o$](위)/l'eau[lo](물)"와 형태론적 대립 "le[$l{\partial}$](정관사, 남성단수)/les[le](정관사, 복수)"등에서 "묵음 e"는 분명히 음운론적 역할을 하고 있다. 본 논문에서는 이와 같이 음색이 복잡하게 나타나는 "e muet"의 문제를 리듬단위, 문맥적 분포 및 음절모형 측면, 즉 음성학 및 음운론적 측면에서 다양하게 분석하여 그 본질을 규명해 보고 "e muet"탈락현상을 TCG(Theorie de Charme et de Gouvernement) 측면에서 새롭게 해석해 보았다.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2006.02a
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• pp.109-114
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• 2006

최근 Human 지놈 프로젝트를 포함한 다양한 종의 지놈 프로젝트가 수행되고 수많은 지놈정보가 생산되고 있으며 이를 해석하고 서로 연관성를 찾기 위한 다양한 연구가 진행되고 있다. 즉 최신 생명공학과 관련된 연구방향이 DNA의 구조적 해석에서 기능 해석과 유전자들의 상호연관성을 규명하는 방향으로 변화하고 있으며 이를 위한 강력한 도구로서 DNA microarray (DNA chip)는 방대한 양의 지놈 정보를 이용하여 단시간에 대량으로 고속처리하여 효율적으로 유전자 기능을 분석할 수 있는 주목받고 있는 방법이다. DNA microarray 실험과 분석에 있어 데이터분석, 재현성, 종간의 비교, 확인실험 및 비용 등의 문제가 있지만 유전자발현양상 데이터로부터 정확한 환자의 예후를 예측할 수 있는 비교적 적은 유전자 그룹의 진단마커를 찾거나, 하나의 유전자가 아니라 mouse 전체 지놈의 유전자발현 패턴을 인간의 암을 위시한 각종 질병 연구를 위한 발현 신호나 변화 등을 발견하여 신약개발 등에 활용하고자 하는 시도가 활발히 진행되고 있다. 서로 다른 종간에 비슷한 phenotype의 유전자발현도 진화적으로 보존되었다는 전제 하에서 지놈 sequence의 비교연구가 가능하고 DNA microarray 발현 데이터에 근거하여 독립적으로 각 종간의 유전자발현패턴을 비교함으로써 난치병 등을 새롭게 분류할 수 있다. 즉, 암세포 등에서 유전자발현 양상은 유전학적, 환경적 alteration들이 잘 반영되어 있다고 간주하고, 이러한 양상을 바탕으로 인간의 암을 위시한 다양한 질병 연구를 위한 최적의 mouse 모델을 찾을 수 있고, 이는 결국 새로운 치료 방법 개발이나 맞춤의학 실현에 중요한 역할을 할 것으로 기대된다. 특히 pathway 타겟으로 하는 치료를 위해서는 Human-mouse 비교를 통한 발현 신호를 찾는 것이 진단에서는 매우 유용한 방법이다. 이를 위한 고성능의 분석방법이나 시스템의 개발이 중요하게 된다.. 관류의 정도와 조영증강정도를 중심으로 관류 MR 영상소견과 조직학적 소견을 관련지어 분석하였다. 결과: 조영증강 T1강조MR영상에서 환상조영증강을 보이는 다형성 교보세포종 2예에서는 변연부 외륜이 고관류를, 중심부의 괴사부위는 저관류로 나타났다. 저등급 교종은 경계가 불분명한 저관류부위로 보였다. 뇌농양 2예는 변연부 외륜이 경도의 고관류를, 중심부는 저관류로 나타났다. 뇌수막종은 미만성의 균일한 중등도 혹은 고도의 고관류로 보였으며, 임파종과 배아종은 경계가 명확한 저관류부위로 나타났다. 신경세포종은 종괴\ulcorner 일부에 중등도 혹은 고도의 고관류부위가 관찰되었고, 전이암은 다수병변중 일부에서 중등도의 고관류를 보였다. 방사선괴사는 저관류부위내에 국소적 고관류부위를 보였다. 결론: 관류 MR영상은 뇌종양의 관류상태를 비교적 잘 반영하며, 조직학적 특성을 예측하는데에 도움을 주 수 있을 것으로 기대된다. 뇌종야에서의 관류MR영상의 분명한 역할을 규명하기 위해서는 앞으로 더 많은 임상적 연구가 필요할 것으로 생각된다.조증 환자의 자극성 전타액내 lactobacilli양은 peroxidase system을 함유한 세치제를 사용한 군에서 대조군에 비해 상대적으로 낮게 나타났으나(p = 0.067) 통계학적 유의성은 없었다.같은 예에서 찾아 볼 수 있다. 첫째, 발음상으로 동사의 변화형에서 "porte[$p{\jmath}rte$](들다: 현재형), porte[$p{\jmath}rte$](과거분사형), porta[$p{\jmath}rte$](단순과거형)"등이 대립되며, 이휘 "Porto[$p{\jmath}rte$](포르토)"와도 대립된다. 둘째, 어휘적 대립 "le haut[$l{\partial}o$](위)/l'eau[lo](물)"와 형태론적 대립 "le[$l{\partial}$](정관사, 남성단수)/l

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.103-110
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• 2012

The flow field, fuel-air mixing, and behaviors of turbulent flames have been investigated using the large eddy simulation (LES) numerical technique in a premixed swirl combustor equipped with EV double cone burners. Recirculation zones are generated by the swirl burner, and lean premixed flames are formed within a distance of 0.2 m from the tip of the burner. NOx emission of 0.46 ppm is predicted at 1 atm and an air/fuel ratio of 38.7. However, most of the CO generated in a flame front continues to be oxidized as it moves toward the exit, and CO emission of 5.45 ppm is predicted at the exit. The NOx emission can be reduced by decreasing the pressure and air/fuel ratio. The characteristics of NOx emission have been investigated through RANS simulations for various fuel injection types, and it is found thereby that five-lance-hole injection produces the lowest NOx emission rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.196-205
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• 2016

The exhaust gas discharged by cars not only threatens the health of the human body, but also contributes to global warming, due to the resulting increase in the concentrations of ozone, fine dust and carbon dioxide. Therefore, the government has steadily implemented careful inspection systems for exhaust emissions, in order to efficiently regulate the exhaust gas of cars. Studies on reducing the exhaust emissions of automobiles have been conducted in various fields, including ones designed to reduce the generation of HC, NOx, and $CO_2$ in the exhaust emission of vehicles. However, there have been insufficient studies on the reduction of the exhaust emission for old diesel vehicles. To develop careful inspection systems for the exhaust emissions of old diesel vehicles, studies on the reduction of the exhaust emissions and improvement of power are necessary by cleaning the carbon sediment in both the intake manifold and injector. Therefore, in this study, we analyzed and compared the amounts of gas emitted when simultaneously cleaning or not cleaning the intake manifold and injector of diesel automobiles with mileages over 80,000 km and operating periods over 5 years. The experimental results showed that in the case where the intake manifold and injector were simultaneously cleaned, there was a decline of 75.2% in the gas emission compared to the cases where only the manifold or injector is cleaned. Also, it was found that simultaneously cleansing the intake manifold and injector enabled the exhaust standard to be satisfied for less than 30% within 8.5 sec.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.908-914
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• 2017

In this study, we developed a system that automatically removes the scale in the piping by using electrolysis principle in order to solve the cooling performance of the refrigeration and air conditioning system by acting as heat resistance in the heat transfer process by forming the scale in the heat exchanger for refrigeration air conditioning. We want to check the performance through experiments. Therefore, by circulating the treated water using the principle of electrolysis without stopping the system, Ca, Mg and $SiO_2$ are precipitated in the form of solids and discharged to the outside of the pipe system, thereby preventing scale formation in the pipe and removing the scale. Thereby maintaining the heat transfer performance of the pipe. As a result of the experiment, the heat transfer rate of the scaled pipe was 86.66% when the heat transfer rate of the new pipe was 100, and the heat transfer rate was recovered to 90.5% when the scaled pipe was operated for 1 month. The heat transfer rate recovered to 97.86% when driving for two months and to 98.72% for three months. It was confirmed that the scaling effect of the scale formed in the piping was understood in a relatively short experiment period, and the heat transfer performance was also influenced.