• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.868-876
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• 2014

The objective of this study is focused on the analyzing combustion, carbon monoxide and hydrocarbon emission characteristics of marine diesel oil, utilized for naval propulsion engine, with varying pre-post injection timing of an optically accessible single cylinder engine. And also the combustion process is analyzed by means of a high speed camera visualization. On the result of retarding pre-injection timing toward main injection timing, the mean effective pressure and maximum pressure of combustion chamber are increased; however, the heat release rate is decreased. Furthermore, the emission rates of carbon monoxide and hydrocarbon are reduced in this case. In hence, when a post-injection timing is advanced, the mean effective pressure and maximum pressure are increased, because the combustion has been performed under the high temperature and high pressurized environment during main injection time, and the emission rates of carbon monoxide and hydrocarbon are increased. From the experimental results, it considered that retarding of pre-injection timing affects to shorten the ignition delay of main injection clearly, and to raise the flame intensity comparing to the advanced state. The ignition delay during post-injection is not appeared at any post-injection time, but the flame intensity has been weakened gradually according to the retarding of post-injection timing.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.11a
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• pp.59-62
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• 1999

1. 미스트를 장시간 분사시킬 경우 분사기간동안 온도강하는 분사량에 무관하게 일정하나 분사종료 후 온도상승은 분사량이 많으면 온도상승이 현저히 지연된다. 반면 증가된 습도는 장시간 유지되기 때문에 적정 분사량이 존재한다. 2. 시설하우스내 고온장애와 습도장애를 극복하고 보다 유리한 실내환경을 유지하기 위해서는 적정 미스트 분무량을 유지시켜야 하며 동시에 분무시간과 휴지시간을 충분히 고려해야만 한다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.323-328
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• 2002

양파의 껍질에 칼금을 내고 꼭지와 뿌리를 절단한 후 회전하는 두 개의 롤러 위에 양파를 낙하시켜 구르게 하면서 그 위에 고압공기를 분사시켜 양파의 외각 껍질을 제거하는 공기분사식 박피장치의 최적 작동조건을 구명하기 위하여 수행한 시험결과를 요약하면 다음과 같다. 1, 박피장치에 고압공기를 분사하지 않았을 때, 롤러의 원주속도가 빠를수록, 양파의 무게가 가벼울수록 구름소요시간은 줄어들었고 직경방향 구름율이 가장 높았는데, 직경방향 구름소요시간이 가장 짧게 나타나는 주롤러의 원주속도는 2.4 m/s이었다. 2. 주롤러의 원주속도 2.4 m/s일 때 양파의 무게, 분사공기압 및 칼금수가 증가할수록 박피율은 증가하였으며, 박피율이 가장 높은 조건은 칼금수 4개, 분사공기압 3.5 kg/$cm^2$이상이었다. 3. 박피소요시간은 칼금수가 많을수록, 분사공기압이 높을수록 짧아지는 것으로 나타났고, 칼금수를 4개로 하고 분사공기압을 4.0 kg/$cm^2$이상으로 하면 박피소요시간을 2초 이하로 유지할 수 었다. 4. 양파의 껍질강도는 저장기일과 조건에 따라 다르므로 모든 양파의 박피를 위해서는 분사 공기압을 4.0 kg/$cm^2$이상으로 하고 공기분사시간을 2초에서 5초가지 조절할 수 있는 장치를 부착하는 것이 좋을 것으로 판단된다. 5. 시험에 사용된 양파는 무게는 150~350$\pm$30 g, 직경 60~120 mm의 크기로 우리나라에서 생산되는 양파의 98%에 적용이 가능할 것으로 생각된다.

• Composites Research
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• v.37 no.2
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• pp.76-85
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• 2024

In this paper, a composite maintenance robot using carbon fiber spray method was developed that automatically sprays mixture was created for repair to damaged areas to repair them. To develop a robot, a repair process was developed in which a mixture of milled carbon fiber, epoxy resin, and hardener is sprayed and consolidated on the damaged area. To automate the repair process, an EOAT based on a collaborative robot was developed that can automatically suction and spray the mixture onto the damaged area. To evaluate the repair performance of the robot, 0° and 90° unidirectional specimens were manufactured and tested in accordance with ASTM D3039. Tests were performed on undamaged specimen, damaged specimen, and repaired specimen by a robot after damaged. As a result of the specimen test, the tensile strength of the 0° and 90° specimens was recovered by 10% and 90% after repair. Based on the test results, the repair performance of the developed composite maintenance robot was verified.

• Industry Promotion Research
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• v.4 no.1
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• pp.21-27
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• 2019

This study is about the bidet which is used to clean the anal and local parts after the user seated on the left side of the toilet in the toilet. The cleaner of the bidet which is contaminated from various bacteria and dirt is washed clean with clean water to keep it clean The present invention relates to a cleaning device for a bidet cleaner that hygienically maintains a bidet used by a plurality of users. As a result of developing and studying a bidet nozzle that can be implemented with a bidet nozzle and a washing nozzle for automatically washing the jetting head of the bidet and the jetting head, the optimum jetting time of the nozzle after the hydraulic jetting is 1 second To 10 seconds, it was confirmed that the nozzle cleanliness of an average of 5 seconds was maintained at 100%. Subsequent studies will require further study of the durability of the product and the cleaning safety at a pressure of $5kg/mm^2$. Toilet bidet is a product that is closely related to the safety and life of the people, but the development of various technologies is still insufficient. Therefore, it is meaningful that this study contributed to the quality of life of the people by continuously researching and developing the bidet.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.214-214
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• 2003

제지산업에 경쟁력을 부여할 수 있는 방법의 일환으로 제지용 도공안료의 표면개질을 시도하였다 은(Ag)이 항균력이 있다는 것이 여러 사람에 의해 증명된바 있으므로 이 은의 항균력을 제지용 무기안료에 이산화티탄과 함께 표면개질하고 다기능성 복합 항균분체를 설계하였다. 표면개질장치에 설치한 기상분사장치를 통해 은 용액을 고압기상분사로 TiO$_2$입자 표면에 Coating 하였다 이때의 분무각도는 60$^{\circ}$이고 오리피스 직경은 0.6mm, 분사 압력은 14kgf/$\textrm{cm}^2$ 이다. TiO$_2$에 은 용액을 기상분사하여 코팅시킨 후 표면개질 계산식에 의한 배합비로 모입자(clay, CaCO$_3$, PE)와 자입자(TiO$_2$)를 혼합하였고, 분체의 대전현상을 이용하여 모입자 주위에 자입자를 부착시킨 후, 고속기류중 충격력으로 표면개질처리를 하였다 표면개질 장치를 사용하여 제지용 무기안료 표면에 은용액이 코팅된 TiO$_2$를 개질 시켰다. 각종 물성(항균성, 백색도, 산란도)과 XRD, SEM 측정을 통해 기능성 항균분체의 실용방안 가능성에 대하여 조사하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1019-1024
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• 2011

The gaseous fuel injection(GFI) type of LPG fuel-supply system is more advantageous than liquefied fuel injection(LFI) from the viewpoint of durability and cost reduction. However, compared with LFI types of LPG fuel-supply systems, in the GFI systems it is difficult to achieve precision fuel metering because of the compressible characteristic of the gaseous fuel. In this study, a Helmholtz resonator is proposed as an appropriate system for precision fuel metering in GFI systems, and the effects of the Helmholtz resonator on the fuel metering are simulated by the commercial flow-network-analysis package Flowmaster.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.10
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• pp.102-111
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• 2004

The procedure of design and manufacture of sub-scale combustor using bipropellant swirl injector with external mixing for a liquid rocket engine are described. The results of cold flow test, ignition test and combustion test of the sub-scale combustor are also given in this paper. The sub-scale combustor uses liquid oxygen(LOx) and kerosene as propellants and has a injector head, an ablative material combustor wall and a water cooled nozzle. The injector head has LOx manifold, fuel manifold, fire face plate, one center swirl injector and 18 main swirl injectors. The cold flow, ignition and combustion tests were successfully performed without damage of combustor. Results of hot firing tests show that combustion efficiency meets the target of design and operations of start and stop cyclogram are stable and high frequency combustion instability does not occur.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.65-69
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• 2006

The flow around a foil with water jet was investigated using the two-frame PIV(CACTUS 3.1) system. After separation, unsteady recirculation & reattachment region was shown a result at reading edge. Separation area was decreased to 1/3 more by waterjet system with coanda effect. Angle of attack and water jet velocity was a variable in the experiment. Each parameters was controlled to $0^{\circ}\sim35^{\circ}$ and $0[m/s]\sim9.2[m/s]$. The separation of flow appearanced at first when the angle of attack is $17^{\circ}\sim18^{\circ}$, However, according to grew up of velocity, beginning of the separation was delayed. In this experiment, vortex and separation region was disappeared by blown when each parameters are low level, and separation controlled more certainly.

• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.90-97
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• 2016

GEO-KOMPSAT-2A and GEO-KOMPSAT-2B are under development by KARI to replace the COMS mission, and will be launched in 2018 and 2019, respectively. GEO-KOMPSAT-2 will be launched and injected into the GTO (Geostationary Transfer Orbit) by the Ariane V launcher. Once injected into the GTO, the satellites are transferred to the drift orbit by applying a series of apogee engine burns. The burn epoch time, duration, and intervals are selected such that the satellite is placed closest to the target drift longitude, or at the drift start longitude. For GEO-KOMPSAT-2, four or five LAE (Liquid Apogee Engine) burns will be applied for drift orbit injection. This paper establishes the GEO-KOMPSAT-2 LAE burn plan, considering predefined constraints and adjustments, taking into account the perturbing forces. Two approaches have been analyzed: the first is a single shot approach, whereas the other is an iteration based optimal solution. Optimal solution has been obtained using the Focusleop, a geostationary satellite LEOP tool.