• International Journal of Automotive Technology
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• v.3 no.1
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• pp.33-40
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• 2002

Increasingly stringent emission regulations of EU and CARB (California Air resource Board) require mandatory OBD (On Board Diagnostics) far the catalytic converters of a vehicle. It demands that MIL(Malfunction Indication Light) should be tuned on to inform the driver of catalytic converter failures. Currently dual oxygen sensor method Is widely used for the converter OBD. However, since it works only alter converter light-off, it has a serious limitation when applied to TLEV or more stringent emission regulations where more than 85% of total emission is coming out before converter light-off. In addition, a recent development in catalyst material. coating technology and additive catalysts leads to a much improved OSC (Oxygen Storage Capacity) after converter light-off, current methods are very difficult to determine levels of converter aging. Therefore, it is desired to develop an OSC detecting method before converter light-off to diagnose converter failures with higher reliability. In this study, OSCs of converters are measured by an absolute measuring method and a dynamic measuring method, and some of fundamental ideas are suggested about converter OBD before converter light-off. The converters are aged with two different aging methods; those are a furnace aging and an engine bench aging: to represent aging conditions in actual field applications. Dual oxygen sensor method at the lower temperature than light-off is also studied at a model gas bench with the converters. It is fecund that there is a certain point in temperature lower than light-off where difference due to aging level becomes maximum, thus a proper dynamic method to effectively monitor catalytic converters could be implemented fur the range lower than light-off temperatures. With this result, the aging level of converters is examined at an engine bench.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.1-7
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• 2018

A combustion test for a supersonic combustor was conducted using a direct-connected type supersonic combustor test facility. The facility was verified for the capability of simulating required flow conditions. The test condition was maintained at Mach 2.0, $915^{\circ}C$ and 496 kPa for 15 s. Using gaseous hydrogen as the fuel, the combustor model was also tested for its ignition and flame holding capability at the fuel equivalence ratio of 0.12. Combustion efficiency was 71%, and the supersonic flow regime was obtained at this test condition.

• Environmental and Resource Economics Review
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• v.12 no.3
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• pp.515-529
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• 2003

This theoretical model makes three contributions to the study on economic growth and environment. First, emissions are generated during final goods production and technology accumulation. Second, this paper assumes that pollution is directly increasing with increase in final goods output or in consumption. Third, we use reproducible factors associated with labor and capital input in production function and assume constant return to scale in reproducible factors. From growth rate condition we derived, increases in reproducible factors, increases in productivity of either the abatment or technology sector, and decrease in social discount rate would increase the sustainable growth rate. In empirical test, the environmental degradation did not effect the economic growth rate though other factors satisfied the growth rate condition equation. However, through the reinterpretation of this result, we found indirectly the fact of that an inverted U relationship between air pollution and economic growth rate would exist in 20 OECD countries using a panel data for the period of 1986~1995.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.1
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• pp.8-15
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• 2011

In this paper, we propose a new structure modeling algorithm from 3D cloud points of terrestrial LADAR data. Terrestrial LIDAR data have various obstacles which make it difficult to apply conventional algorithms designed for air-borne LIDAR data. In the proposed algorithm, the field data are separated into several clusters by adopting the structure extraction method which uses color information and Hough transform. And cluster based Delaunay triangulation technique is sequentially applied to model the artificial structure. Each cluster has its own priority and it makes possible to determine whether a cluster needs to be considered not. The proposed algorithm not only minimizes the effects of noise data but also interactively controls the level of modeling by using cluster-based approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.2014-2026
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• 1997

In this paper, the performances of wireless asynchronous transfer mode (ATM) cell transmission in mobile work are analyzed. We adopt 16Star QAM as amodulation technique in wireless channel and considered Reed-Solomon, convolutional, and concatenated coding to improve the error rate performances, and also proposed the Partial Concatenated Coding (PCC) technique as UEP(unequal error protection) code for efficient transmission of ATM cell in the air interface. We consider Doppler's effect, Rician fading, and diversity technique of maximal-ratio combining (MRC) for mobile channel model. For performance measure, we analyze bit error rate, ATM cell loss probability, ATM cell error probability, and network performances of ATM cell transmission delay and throughput. The numerical results show that the adoption of PCC is a prospective way for the evolution of future wireless ATM network on mobile environment.

• Transactions of the KSME C: Technology and Education
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• v.3 no.1
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• pp.15-21
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• 2015

In this paper a prediction method of GHP performance is proposed for increasing design accuracy. Two compressors with different capacity and 2311cc gas engine are used for prediction and the target capacity of GHP is 25HP. For predicting GHP performance at first the operation points are randomly selected and then as compared with compressor performance date and heat exchanger characteristic, more accurate operating points are decided through recursive calculation. Lastly engine performance date is used for calculating gas consumption volume. Predicting heating mode performance of GHP, evaporator is separated to the two section of absorbing heat in outdoor air and in engine. From the experimental results, it was found that the simulation model is good for the predicting GHP efficiency and the difference of predicted and measured efficiency is less than 5%.

• Safety and Health at Work
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• v.2 no.4
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• pp.336-347
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• 2011

Objectives: In Korea, an average of 258 workers claim compensation for their noise-induced hearing loss (NIHL) on an annual basis. Indeed, hearing disorder ranks first in the number of diagnoses made by occupational medical check-ups. Against this backdrop, this study analyzed the impact of 19 types of noise-generating machines and equipment on the sound pressure levels in workplaces and NIHL occurrence based on a 2009 national survey on work environments. Methods: Through this analysis, a series of statistical models were built to determine posterior probabilities for each worksite with an aim to present risk ratings for noise levels at work. Results: It was found that air compressors and grinding machines came in first and second, respectively in the number of installed noise-generating machines and equipment. However, there was no direct relationship between workplace noise and NIHL among workers since noise-control equipment and protective gear had been in place. By building a logistic regression model and neural network, statistical models were set to identify the influence of the noise-generating machines and equipment on workplace noise levels and NIHL occurrence. Conclusion: This study offered NIHL prevention measures which are fit for the worksites in each risk grade.

• Journal of Korean Clinical Nursing Research
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• v.26 no.3
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• pp.365-373
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• 2020

Purpose: The purpose of this study was to evaluate the effect of preoperative warming to prevent hypothermia in surgery for patients undergoing total hip replacement arthroplasty under spinal anesthesia. Methods: A randomized experimental study was conducted. Data were collected at an S University hospital in Gyeonggido from December 3, 2019 to March 31, 2020. A random allocation program was used to randomize participants into intervention and control groups. A total of 90 participants were assigned to the study: 30 people were randomized to a pre-warming group using Bair Hugger forced-air warming blankets(Model 505) 30 minutes before surgery, 30 to a pre-warming group 15 minutes before surgery, or 30 to a control group. The findings from 88 participants were analyzed. For data analysis, χ2 test and ANOVA were used utilizing the SPSS 21.0 program. Results: The pre-warming group 30 minutes before surgery had significantly higher body temperature than the control group, from 30 minutes after inducing anesthesia to the end of anesthesia. Body temperature over anesthesia time showed significant differences among the three groups, but there were no statistically significant differences in interactions between time and groups. Conclusion: Warming patients' body for 30 minutes before surgery was effective in maintaining normal body temperature while preventing intraoperative hypothermia.

• Journal of Aerospace System Engineering
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• v.16 no.1
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• pp.70-80
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• 2022

An aerial refueling provides for extension of operational time and range for aircraft and enhances mission effectiveness, hence it application by most military aircrafts. The receiver aircraft should have the aerial refueling clearance that is established by performing technical and operational compatibility assessments to certify it for aerial refueling with a specific tanker model. The compatibility assessment includes aerial refueling handling qualities, functional, fuel, lighting system testing and it is finally verified through flight testing. However, since aerial refueling compatibility assessments have never been performed in Korea, there is no experience to determine the test requirements and the scope and size of the test program for a new development aircraft. This paper therefore introduces the common techniques of aerial refueling and aerial refueling flight test methods to understand the aerial refueling FCS (Flight Control System), OFP (operational flight program) and system validation, and aerial refueling envelope clearance of a fixed wing aircraft for a boom and receptacle refueling system that is being introduced into Korea Air Force.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.5
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• pp.411-429
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• 2015

The Korea Ministry of Environment has established an air quality standard for $PM_{2.5}$ in 2012 and it is effective from January 2015. In this study, we review various aspects of $PM_{2.5}$ in China, including its measurement, modeling, source apportionment, and health effect, and suggest future research directions for $PM_{2.5}$ studies in Korea. Measurements studies for $PM_{2.5}$ have examined organic marker compounds and $^{14}C$ as well as inorganic aerosols for distinguishing sources. Modeling results supported that the control of $PM_{2.5}$ pollution in big city needs effective cooperation between city and its surrounding regions. The major $PM_{2.5}$ sources in China have been identified to be secondary sulfur, motor vehicle emissions, coal combustion, dust, biomass burning, and industrial sources, however, they have seasonal dependency. Especially, the severe haze pollution event during January 2013 over eastern and northern China was driven to a large extent by secondary aerosol formation. Short-term exposure to $PM_{2.5}$ is strongly associated with the increased risk of morbidity and mortality from cardiovascular and respiratory diseases, as well as total non-accidental mortality. Considered previous $PM_{2.5}$ studies in China, analysis of specific organic species using online measurement, chamber experiment for secondary aerosol formation mechanism, and development of parameterizing this process in the model are needed to elucidate factors governing the abundance and composition of $PM_{2.5}$ in Korea.