• Journal of Korean Society for Atmospheric Environment
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• v.23 no.3
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• pp.311-321
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• 2007

Nowadays, concerns have much more growing regarding indoor air quality (IAQ) on the public transportation including railway vehicles. Last year Korea Ministry of Environment (ME) set new guideline for public transportation. In this study several factors were analyzed which may affect comfortableness of railway passenger cabin, and we monitored IAQ parameters (PM10, CO, $CO_2$, VOCs, temperature and humidity) to investigate the present pollution in passenger cabin. In general, the railway air quality was satisfactory. The PM10 and $CO_2$ level on all passenger cabin were below the new guideline level 1 for PM10 $(200{\mu}g/m^3)\;and\;CO_2(2,000ppm)$. Clustering method was carried out to classify the air polluting pattern of the cabin. As a result, the pollutants could be classified to 4 clusters and the origin of pollution is soil, diesel exhaust gas, abrasion of rail and plume.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.83-88
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• 2013

Recently, PCCI (premixed charge compression ignition) combustion is studied to reduce both NOx and PM because of homogeneous mixture formation and lower combustion temperature. It has also merit of increasing thermal efficiency owing to better air-fuel mixure. However, it is well known that PCCI combustion has a weakness in fuel economy because PCCI combustion tends to start before TDC. Therefore, it is necessary to find an optimal conditions for PCCI combustion which maintains reduction of NOx, PM and increase of thermal efficiency. In this study, pPCCI combustion was realized by adding early injection strategy to a conventional diesel engine. In addition, the characteristics of pPCCI combustion was analized by comparing conventional diesel injection strategy. The results show that NOx and PM per power in pPCCI combution were reduced compared to a conventional diesel combustion.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.12
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• pp.1159-1166
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• 2010

Today, detecting the location of moving object has been traced as various methods in our world. In this paper, we preset the system to improve the estimation accuracy utilizing detail localization using radar sensor based on WSN and situational awareness for a calibration (context aware) database, Rail concept. A variety of existing location tracking method has a problem with receiving of data and accuracy as tracking methodology, and since these located data are the only data to be collected for location tracing, the context aware or monitering as the surrounding environment is limited. So, in this paper, we enhanced the distance aware accuracy using radar sensor utilizing the Doppler effect among the distance measuring method, estimated the location using the Triangulation algorithm. Also, since we composed the environment data(temperature, illuminancem, humidity, noise) to entry of the database, it can be utilized in location-based service according to the later action information inference and positive context decision. In order to verify the validity of the suggested method, we give a few random situation and built test bed of designed node, and over the various test we proved the utilizing the context information through route tracking of moving and data processing.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.138-148
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• 1999

Thermal deformations of tension mask under localized heating are analyzed using finite element method and electron beam landing shifts are predicted by the analysis results. In CRT, electron beam landing shifts due to thermal deformations of the tension mask make the color purity of screen worse. In order to get the final results of thermal deformations, firstly the tension processes of the mask and following welding processes between the tensional mask and rail must be analyzed sequentially. And then, nonlinear transient thermo-elastic finite element analysis is performed on every part inside CRT including tension mask, wherein thermal radiation is a main heat transfer mechanism. Because the tension mask has numerous slits, the effective thermal conductivity and effective and effective elastic modulus is calculated, and the tension mask is modeled as a shell without slits. From the displacement results of tension mask, electron beam landing shifts is calculated directly. Experiments are performed to confirm our analysis results. Temperature distributions and beam landing shifts of tension mask are measured and the results are in good agreement with those of analyses.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.169-177
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• 2015

In this study we investigated the regeneration methods for the lean $NO_x$ trap (LNT) catalyst in a 2.2L direct injection diesel engine. The regeneration methods were 1) in-cylinder post fuel injection and 2) external fuel injection strategy. The in-cylinder post fuel injection method uses in-cylinder injectors with the addition of the post fuel injection to supply enough reductants such as CO, $H_2$, THC. The external fuel injection method was enabled by installing a fuel injector with a wide spray angle before the LNT catalyst. Through the engine experiment, the $NO_x$ conversion efficiency, the amount of reductant exhaust gases, fuel consumption, and temperature behavior in the LNT catalyst were evaluated and compared for the two regeneration methods.

• Journal of the Korean Society of Combustion
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• v.20 no.4
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• pp.26-33
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• 2015

American NREL (National Renewable Energy Laboratory) reported that BD20 could reduce PM, CO, SOx and cancerogenic matters by 13.6%, 9.3%, 17.6% and 13% respectively, compared to diesel fuel. BD20 has been being tested on garbage trucks and official vehicles at Seoul City, which is positive on air environment, but negative on combustion by higher viscosity in winter season. This study investigated the combustion characteristics by employing multi cavity piston for improving the deterioration of combustibility caused by the higher viscosity of the biodiesel fuel such as BD20 with the combustion flames taken by a high speed camera and the cylinder pressure diagram. A 4-cycle single cylinder diesel engine was remodeled to a visible 2-cycle engine for taking the flame photographs, which has a common-rail injection system. The test was done at laboratory temperature of about $4{\sim}5^{\circ}C$.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.812-817
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• 2004

Recently drastic improvement of railway technology has been accompanied by the construction of very high-speed tracks. It should be noticed that Continuously Welded Rail(CWR) has played significant role in technical development of railway and that installation of CWR is now being scheduled on existing lines as well as newly-built lines. In general, interaction between CWR and bridge deck takes place on bridge section and additional axial force and displacement is to be developed owing to temperature and braking/acceleration forces. This interaction is known to be mainly governed by span organizations and arrangements of foot bearings. In common practice, movable bearing is stationed and designed on the assumption that it is not able to transfer the horizontal force of upper decks. However, it is well known that horizontal resistance is developed in movable bearings due to friction and that friction coefficient of movable bearing is ranged from 0.03 to 0.20 depending on the material of bearings and magnitude of reactions. Therefore, it is easily reasoned out that friction of movable bearing can influence the mutual behavior of CWR and bridge decks. Suggested in this study is to investigate the validity and efficiency of friction effect of movable bearings in controlling the axial force and displacement of CWR on continuous railway bridges.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.12
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• pp.907-914
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• 2008

This study is mainly focused on the assessment of return, semi return, and returnless fuel supply system for an LPi engine. In order to compare the return type with returnless one with various LPG blends, combustion analysis and cyclic THC emission characteristic were tested at the part load operating condition of the LPi engine. Considering heat balance of each fuel supply systems, pressure and temperature increment of return type showed lower at the fuel rail during idle warm up operation. However, those of returnless type at LPG tank maintained stable and slow increment because the heat transfer from the LPi engine was minimized. Finally, hot restartability of each fuel supply systems were evaluated with the various LPG blends and fuel temperatures. As a result, semi return type has equivalent performance to return type considering combustion and emission characteristic, hot restartability performance for LPi engine.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.223-228
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• 2005

Precast concrete deck has many advantages comparing with the in-situ concrete deck, and has been successfully applied to replacement of the deteriorated decks and to the newly constructed highway bridges in domestic region. In order to apply the precast decks into the railway bridges, however, differences of the load characteristics between the highway and the railway should be properly taken into account including the train load, longitudinal force of the continuous welded rail. acceleration or braking force, temperature change and shrinkage. Proper level of the longitudinal prestress of the tendons that can ensure integrity of the transverse joints in the deck system is of a primary importance. To this aim, the longitudinal tensile stresses induced by the design loads are derived using three-dimensional finite element analyses, design codes and theoretical equations for the frequently adopted PSC composite girder railway bridge. The estimated proper prestress level to counteract those tensile stresses is over 2.4 MPa, which is similar to the case of the highway bridges.

• Journal of the Korea Society of Computer and Information
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• v.24 no.8
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• pp.37-43
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• 2019

The existing smart farm technology has been systematized for the mass production rather than the consumer. There are many problems such as economical aspect to apply to actual rural environment due to aging. The purpose of this study is to apply smart farm technology based on the applicability of population aged in rural areas. Due to the heat wave, the crops in general greenhouse cultivation facilities suffered from damage such as sunlight damage. To minimize such damage, adjust the temperature and humidity environment or install a light-shielding film. However, the workers in the rural areas are aging and the elderly who are farming alone have a lot of difficulties in doing so. In the case of people with weak physical strength, there is a danger that they may lead to safety accidents when carrying heavy loads. In this paper, we propose 'Smart Palm capable of automatic transportation function', applying small smart vehicles that follow workers to existing smart farms to improve and prevent these problems. It is a smart farm that performs the control functions of the existing smart greenhouse environment, installs the rail for each trough, and has a vehicle that follows the worker. The smart app can directly control the greenhouse and the vehicle remotely manually.