• 한국연소학회지
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• 제12권3호
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• pp.16-23
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• 2007

Employing an after-treatment system has almost become a mandatory requirement for Diesel vehicles, which results from a reinforced exhaust regulations as the number of vehicles powered by a Diesel engine increases. The Diesel Particulate Filter (DPF) system is considered as one of the most efficient method to reduce particulate matter (PM); however, the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Temperature, gas composition and flow rate of exhaust gas are important parameters in DPF evaluation processes, especially during a regeneration process. Engine dynamometer and segment tester are generally used in DPF evaluation so far. These test methods, however, could not completely evaluate the effect of various parameters on real DPF, such as oxygen concentration, amount of soot and exhaust gas temperatures. The evaluation of DPF systems using a dump combustor has been verified experimentally and this dump combustor system is likely to be appropriate for the DOC (Diesel Oxidation Catalyst) and SCR (Selective Catalytic Reduction) assessments test, too.

• 동력기계공학회지
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• 제10권2호
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• pp.11-15
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• 2006

The increasing numbers of automobiles keep causing air-pollution problems worse than ever. Nowadays, research on catalyst converter and filter trap as a modern technology is very active because PM is designated as a major cancer material and stringent regulations on this are necessary and required. This research emphasized on the development of Continuously Regenerating DPF technology which was the best particulate matters removing technology of current existing technology because of its superior comparability and high applicability. This experimental study has been conducted with equipped and unequipped a Continuously Regenerating DPF ona displacement 7,000cc diesel engine and compared in terms of engine performance and emission. To measure the emission, D-13 mode is applied and measured quantities of the exhaust gases, particularly in CO, HC, PM, and NOx. Therefore, this research is focused on engine performance and characteristics on exhaust emissions with the application of a Continuously Regenerating DPF in a heavy-duty diesel vehicle.

• 한국자동차공학회논문집
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• 제19권6호
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• pp.10-16
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• 2011

Diesel particulate filter is being recognized that it is the most effective technologies to reduce particulate matter. In this study, to determine the characteristics of the cell-open-type pDPF, we employed p-DPF to exhaust gas tunnel of diesel engine and surveyed filtration efficiency and BPT on the basis of PM which is exhausted from engine. In this paper the soot loading mass in DPF can be predicted from increase of differential pressure of DPF so that we can measure filtration efficiency and Balance Point Temperature (BPT) by soot loading mass. The result of the research showed that the filtration efficiency is 65% in ESC mode with 0.7mm hole diameter. For the results of the characteristics of filtration efficiency and BPT according to mass_exh, we found that if mass_exh increases, filtration efficiency increases and BPT decreases.

• 한국자동차공학회논문집
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• 제17권1호
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• pp.24-34
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• 2009

DPF(Diesel Particulate Filter)s have been used to reduce the most of PM(particulate matters) from the exhaust emissions of diesel engine vehicles. Metal foam is one of promising materials for the DPFs due to its cost effectiveness, good thermal conductivity and high mechanical strength. It can be fabricated with various pore sizes and struct thickness and coated with catalytic wash-coats with low cost. In order to design metal foam filter and analyze the flow phenomena, pressure drop and filtration experiment are carried out. Partial DPF which has PM reduction efficiency of more than 50 % is designed in this paper. Also, CFD analysis are performed for different configurations of clean filters in terms of pressure drop, uniformity index, and velocity magnitude at face of filter. Filter thickness and the gap between front and rear filters are optimized and recommended for manufacturing purpose.

• 한국수소및신에너지학회논문집
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• 제31권6호
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• pp.614-621
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• 2020

Recently, as the fine dust is increased and the emission regulations of diesel engines are strengthened, interest in diesel soot filtration devices is rapidly increased. In particular, there is a demand for technology development for higher efficiency of diesel exhaust gas after-treatment devices. As part of this, many studies conducted to increase the exhaust gas treatment efficiency by improving the flow uniformity of the exhaust gas in the DPF and reducing the pressure drop between the inlet and outlet of disel particle filter (DPF). In this study, computational fluid dynamics (CFD) simulation was performed when exhaust gas flows into the canning reduction device equipped with a 13" asymmetric DPF in order to maintain the flow uniformity in the diesel exhaust system and reduce the pressure. In particular, a study was conducted to find the geometry with the smallest pressure drop and the highest flow uniformity by simulating the DPF I/O ratio, exhaust gas temperature, inlet-outlet pressure and flow uniformity according to the geometry and hole size of distributor.

• 한국철도학회논문집
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• 제12권4호
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• pp.457-464
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• 2009

디젤 엔진 매연 필터의 입구부와 배출 가스 배출을 위한 배기관 연결을 직선 또는 곡선으로 형태로 연결하였을 때의 DPF 입구 유속 분포를 $STAR-CD^{(R)}$ 전산해석 프로그램을 사용하여 시뮬레이션하였다. 곡관의 형상을 나타내는 3 종류의 수치해석 용 격자 모델을 사용하여 DPF 입구에서의 유속 분포를 시뮬레이션 하였다. 피토관을 2차원 이송장치에 탑재하고 위치를 이동시키며 측정한 유속 분포와 동일한 조건에서 시뮬레이션한 결과와 비교하였다. DPF 입구와 $90^{\circ}$의 곡관이 연결된 조건에서 CFD 해석을 수행한 결과 입구 단면에서의 유속 분포가 말발굽 형태를 나타내었으며 최대 유속값이 DPF 중심축에서 약간 벗어난 위치에서 나타나고 있다. 이러한 CFD 해석결과는 실험 결과와 비교적 잘 일치하였다.

• Tribology and Lubricants
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• 제34권6호
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• pp.292-299
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• 2018

The objective of this research is to investigate the impact of engine oil aging on PM(Particulate Matter), exhaust gases, and DPF. It is widely known that the specification of a lubricant and its consumption in an ICE considerably influences the release of regulated harmful emissions under normal engine operating conditions. Considering DPF clogging phenomena associated with lubricant-derived soot/ash components, a simulated aging mode is designed for DPF to facilitate engine dynamometer testing. A PM/ash accumulation cycle is developed by considering real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for ash accumulation. The test duration for DPF aging is approximately 300 h with high- and low-SAPs engine oils. Detailed engine lubricant properties of new and aged oils are analyzed to evaluate the effect of engine oil degradation on vehicle mileage. Furthermore, physical and chemical analyses are performed using X-CT, ICP, and TGA/DSC to quantify the engine oil contribution on the PM composition. This is achieved by sampling with various filters using specially designed PM sampling equipment. Using high SAPs engine oil causes more PM/ash accumulation compared with low SAPs engine oils and this could accelerate fouling of the EGR in the engine, which results in an increase in harmful exhaust gas emissions. These test results on engine lubricants under operating conditions will assist in the establishment of regulated and unregulated toxic emissions policies and lubricant quality standards.

• 한국발생생물학회지:발생과생식
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• 제27권2호
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• pp.91-99
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• 2023

The sea cucumber, Apostichopus japonicus, is one of the most valuable aquatic species. The color of body wall and appearance are important for the value of sea cucumbers. To examine expression pattern of long-chain acyl-coenzyme A dehydrogenase (LCAD), nuclear distribution C-containing protein 3 (NUDCD3), and receptor tyrosine kinase Tie-1 (TIE1), previously reported as differently expressed genes during the pigmentation of sea cucumber, we analyzed the temporal profiles of LCAD, NUDCD3, and TIE1 mRNAs in LED-exposed and light-shielded A. japonicus. Real-time quantitative PCR revealed that the LCAD, NUDCD3, and TIE1 mRNAs from the juveniles at 40-60 days post-fertilization (dpf) exhibited increasing patterns as compared to those of an early developmental larva (6-dpf). At 60-dpf juveniles, the LCAD and TIE1 mRNA levels of LED-exposed individuals were higher than those of light-shielded ones, whereas at 40-dpf and 50-dpf juveniles, the NUDCD3 mRNA expression was higher in the light-shielded condition (p<0.05). In the pigmented juveniles (90-dpf), the LCAD and TIE1 mRNA levels tended to show higher levels in red individuals than those in green ones, but there was a conversely higher level of NUDCD3 mRNA in green larva. In situ examination of LCAD and NUDCD3 mRNAs in light-shielded 6-dpf larva revealed that both genes are mainly expressed in the internal organs compared to the body surface. Together, these results may provide insights into the differential gene expression of LCAD, NUDCD3, and TIE1 during pigmentation process of the sea cucumber.

• Physical Therapy Rehabilitation Science
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• 제12권3호
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• pp.259-267
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• 2023

Objective: Rehabilitative ultrasound imaging is a safe and noninvasive technique for evaluating muscle thickness. A dual probe-fixing frame (DPF) can provide visual feedback during exercises targeting specific muscles. The purpose of this research was to verify the reliability and validity of the DPF for dual-probe ultrasound (DPU)-based visual feedback exercises, allowing users to use both hands freely. Design: This cross-sectional study used repeated measures to compare muscle thickness measurements obtained using the handheld device and DPF with DPU. Methods: Twenty healthy adults participated in the study. Measurements were taken over two sessions, with a two-day interval between the sessions. The thicknesses of the rectus abdominis (RA) and transverse abdominis (TrA) muscles were measured using DPU. The DPF with DPU developed by the research team, was used along with a laptop-based muscle viewer. Bland-Altman analysis and intraclass correlation coefficients (ICCs) calculations were used in statistical analyses to evaluate agreement and reliability, respectively. Results: The results of the Bland-Altman analysis showed small average differences between the handheld and DPF methods for both RA and TrA muscle thicknesses. Inter-rater reliability analysis showed high ICC values for DPF measurements of both RA (0.908-0.912) and TrA (0.892-741) muscle thicknesses. Intra-rater reliability analysis also showed good ICC values for measurements taken by a single examiner over two days. Conclusion: The findings of this study demonstrate that the DPF provides reliable and valid measurements of muscle thickness during visual feedback exercises using the DPU.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2005년도 추계학술대회 논문집
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• pp.491-493
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• 2005