• Transactions of the Korean Society of Automotive Engineers
• /
• v.17 no.5
• /
• pp.91-96
• /
• 2009

The number of vehicles applied diesel engine are rapidly rising for fuel economy. Accompanying this trend, application of an after-treatment system is strictly required as a result of reinforced emission regulation. The Diesel Particulate Filter (DPF) system is considered as the most efficient method to reduce particulate matter by car makers but also in retrofit market. In this paper we discussed the optimization of active regeneration timing by comparing the fuel consumption from back pressure caused by PM loading and from active regeneration. The effects of back pressure of DPFs during PM loading, active regeneration condition and engine emission(PM) on additional fuel consumption are experimentally investigated and the proper regeneration timings according to DPF systems and fuel loss for 160,000km are determined.

• Journal of ILASS-Korea
• /
• v.22 no.2
• /
• pp.87-95
• /
• 2017

Recently, as the interest in environmental issues have increased around the world, the regulation on vehicle exhaust have been tightened in each country. To satisfy such tightened exhaust regulation, automotive manufactures are forced to equipped Diesel Particulate Filter (DPF) at Diesel vehicles. If DPF is used for a long time, DPF regeneration should be performed. The objective of this study is to research on post injection for DPF regeneration. The result of the study was that it was desired that retarding post injection timing, lower load of engine and smaller the amount of main fuel injection, for DPF regeneration. Oil dilution was tended to increase as load was lower, amount of post injection was increased, and post injection timing was retarded.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.2
• /
• pp.60-66
• /
• 2014

A control oriented model of the Lean $NO_x$ trap (LNT) was developed to determine the timing of $NO_x$ regeneration. The LNT model consists of $NO_x$ storage and reduction model. Once $NO_x$ is stored ($NO_x$ storage model), at the right timing $NO_x$ should be released and then reduced ($NO_x$ reduction model) with reductants on the catalyst active sites, called regeneration. The $NO_x$ storage model simulates the degree of stored $NO_x$ in the LNT. It is structured by an instantaneous $NO_x$ storage efficiency and the $NO_x$ storage capacity model. The $NO_x$ storge capacity model was modeled to have a Gaussian distribution with a function of exhaust gas temperature. $NO_x$ release and reduction reactions for the $NO_x$ reduction model were modeled as Arrhenius equations. The parameter identification was optimally performed by the data of the bench flow reactor test results at space velocity 50,000/hr, 80,000/hr, and temperature of $250-500^{\circ}C$. The LNT model state, storage fraction indicates the degree of stored $NO_x$ in the LNT and thus, the timing of the regeneration can be determined based on it. For practical purpose, this model will be verified more completely by engine test data which simulate the NEDC transient mode.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.6
• /
• pp.96-102
• /
• 2004

The diesel particulate filter(DPF) is effective for particulate removal from diesel engine under a variety of conditions, and then the regeneration strategies is very important in the aspects of engine fuel consumption and engine durability. This paper addresses the changes of Peugeot 406 vehicle engine parameters(fuel injection timing, period, rail pressure, emissions exhaust temperature so on) during DPF regeneration. additionally, checked the soot loading mass with mileage and the change of fuel consumption and performance with ash accumulation.

• ETRI Journal
• /
• v.29 no.5
• /
• pp.633-640
• /
• 2007

We report an experimental demonstration of 40 Gbps all-optical 3R regeneration with all-optical clock recovery based on InP semiconductor devices. We also obtain alloptical non-return-to-zero to return-to-zero (NRZ-to-RZ) format conversion using the recovered clock signal at 10 Gbps and 40 Gbps. It leads to a good performance using a Mach-Zehnder interferometric wavelength converter and a self-pulsating laser diode (LD). The self-pulsating LD serves a recovered clock, which has an rms timing jitter as low as sub-picosecond. In the case of 3R regeneration of RZ data, we achieve a 1.0 dB power penalty at $10^{-9}$ BER after demultiplexing 40 Gbps to 10 Gbps with an eletroabsorption modulator. The regenerated 3R data shows stable error-free operation with no BER floor for all channels. The combination of these functional devices provides all-optical 3R regeneration with NRZ-to-RZ conversion.

• Journal of Positioning, Navigation, and Timing
• /
• v.2 no.1
• /
• pp.9-17
• /
• 2013

In this paper, a pseudorange correction regeneration algorithm was developed to improve the positioning accuracy of DGPS using multi-reference stations, and the optimal minimum number of reference sites was determined by trying out different numbers of reference. This research was conducted using from two to five sites, and positioning errors of less than 1 m were obtained when pseudorange corrections are collected from at least four reference stations and interpolated as the pseudorange correction at the rover. After determining the optimal minimum number of reference stations, the pseudorange correction regeneration algorithm developed was tested by comparison with the performance of other algorithms. Our approach was developed based on an exponential model. If pseudorange corrections are regenerated using an exponential model, the effect of a small difference in the baseline distance can be enlarged. Therefore, weights can be applied sensitively even when the baseline distance differs by a small amount. Also weights on the baseline distance were applied differently by assigning weights depending on the difference of the longest and shortest baselines. Through this method, the positioning accuracy improved by 19% compared to the result of previous studies.

• Journal of Periodontal and Implant Science
• /
• v.44 no.6
• /
• pp.293-299
• /
• 2014

Purpose: Systemic disease can manifest oral signs at an early phase, which may be crucial for the diagnosis and timing of treatment. This report describes two patients who presented with gingival enlargement as an early sign of acute leukemia. Methods: Two patients presented with oral symptoms including severe gingival enlargement. The progress of their symptoms was associated with underlying systemic disease. Results: The patients were transferred to the Department of Hematology and diagnosed with acute myelomonocytic leukemia. They received appropriate treatment and survived. Conclusions: Gingival enlargement can be caused by underlying systemic diseases. Accurate diagnosis and timely referral are important for preventing a fatal situation. It must be emphasized that some oral signs and symptoms may be closely correlated with systemic diseases.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.20 no.4
• /
• pp.150-155
• /
• 2012

Lean NOx Trap (LNT) catalysts are capable of reducing exhaust NOx emissions from diesel engines. LNT stores NOx in lean condition and exhausts N2 by reducing NOx in rich condition. NOx reduction characteristic of LNT catalysts using throttle position sensor and fuel injection timing control for light-duty diesel engine was investigated. In contrast to SCR system, LNT catalyst uses diesel fuel in resuctant. Also if the concentration of reductant is exceeded, excessive amount of reductant will slip throughout LNT and cause another emission problem. Thus LNT regeneration with precise engine control established that can make higher NOx conversion efficiency and lower fuel penalty, prevent another emission problem. NOx and reductant concentration were measured by the NOx sensor and Mexa7100D equipped inlet and outlet of catalyst. As a result of engine test, regeneration strategy has reached high of 77.8% NOx conversion efficiency according to engine operation condition. Moreover, we have proved that it is possible to use regeneration strategy of LNT within 5% fuel penalty.

• Journal of Korean Society of Forest Science
• /
• v.110 no.3
• /
• pp.295-307
• /
• 2021

This study proposed a field-applicable natural regeneration method using natural seeding to afforest a secondary growth forest after felling in Larix kaempferi plantations. In 2016, an experimental site was established usingseed-tree and clear-cutting methods in Gapyeong, Gyeonggi-do, South Korea. Characteristics of seed fructification and inflow in the natural regeneration site were analyzed along with an experimental site in Bonghwa, Gyeongsangbuk-do, which was established in 2014. As a result, the number of seeds per individual tree of V age class L. kaempferi was 690,340 seeds in a good year, with an estimated 13.8 million seeds per ha fruited in natural regeneration sites of L. kaempferi with 25 seed-trees per ha. Seed dispersal began in September and germination rates of seeds dispersed until November were greater than 40%. Reserved seed-tree sites showed the highest amount of seed inflow, followed by the seed-tree site and clear-cut site in descending order. The reserved seed-tree method performed better than other methods for evenly scattering seeds. Therefore, the timing of logging and seedbed generation for natural regeneration of L. kaempferi is estimated to be most effective before September when seeds are purposefully scattered using the reserved seed-tree method as an effective method for uniform seed supply.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.29 no.4
• /
• pp.333-339
• /
• 2007

Adequate bone quantity is one of the important factor to obtain osseointegration after implantation. Guided bone regeneration (GBR) has widely used in implantation for reconstruction of bony defects. Since introducing this procedure, there are many studies about survival rate of implants, changing in surrounding bone volume after function. The purpose of this study was to evaluate the amount of resorption according to placement timing and survival rate after function. The subjects were patients who had been operated with GBR from Jun 2003 to Jun 2004 in Seoul National University Bundang Hospital. They were divided into simultaneous and delayed placement group. The follow up had been performed at the time of just after GBR, 1, 3, 6, 12, 24-month later and standard periapical radiographs were taken to estimate the bone level at the time. The total average of bone level change in radiographs was 1.94mm(${\pm}0.25$), and 1.92mm(${\pm}0.72$) in simultaneous installation, 2.03mm(${\pm}0.25$) in delayed installation. In this report, the survival rates were 92.2% in simulataneous group and 92.3% in delayed group. Insufficient primary stability, early contamination of wound, overloading, poor oral hygiene, and infection were thought to be associated factors in the failed cases.