• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.6
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• pp.607-614
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• 2013

Nowadays, automotive manufacturers have developed various technologies to improve fuel economy and reduce harmful emissions. The ultra-lean direct injection engine is a promising technology because it has the advantage of improving thermal efficiency through the deliberate control of fuel and ignition. This study aims to investigate the development of a spray-guided-type lean-burn LPG direct injection engine through the redesign of the combustion system. This engine uses a central-injection-type cylinder head in which the injector is installed adjacent to the spark plug. Fuel consumption and combustion stability were estimated depending on the ignition timing and injection timing at various air-fuel ratios. The optimal injection timing and ignition timing were based on the best fuel consumption and combustion stability.

• Journal of Gifted/Talented Education
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• v.20 no.1
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• pp.79-106
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• 2010

Leadership education is part of the goals of special education for the gifted of computer science. However, there has been little research effort on leadership curriculums and programs specially designed for the gifted of computer science by reflecting their characteristics. Thus this paper was conducted to design educational contents of leadership for the gifted of computer science as follows:First, common elements were extracted from the goals and characteristics of special education for the gifted of computer science and from the previous studies through analysis. Then basic data were selected helpful to choose educational contents of leadership for the gifted of computer science. Second, the definitions and characteristics of leadership were analyzed along with the previous studies to find common elements. By defining relations between the gifted of computer science and leadership, the investigator also examined the leadership characteristics to be considered when choosing educational contents. Third, educational contents of leadership for the gifted of computer science were selected and designed based on the leadership elements developed by the Korean Educational Development Institute(2005). Fourth, leadership activity logs and reading materials were developed of the education for the gifted of computer science based on the educational contents for their leadership. And fifth, Delphi analysis was carried out to test the validity of the leadership activity logs and reading materials developed in the study in two sessions; the first one tested the overall design of the educational contents, and the second one did the detailed contents of the activity logs and reading materials.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.118-128
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• 2016

As the interest on the air-pollution is gradually rising up at home and abroad, automotive and fuel researchers have been working on the exhaust emission reduction from vehicles through a lot of approaches, which consist of new engine design, innovative after-treatment systems, using clean (eco-friendly alternative) fuels and fuel quality improvement. This research has brought forward two main issues : exhaust emission and PM (particulate matter) particle emissions of gasoline vehicle. Exhaust emission and PM particle of automotive had many problem that cause of ambient pollution, health effects. In addition, researcher studied the environment problems of the MTBE contained in the fuel as oxygenate additives. The researchers have many data about the health effects of ingestion of MTBE. However, the data support the conclusion that MTBE is a potential human carcinogen at high doses. Based on the oxygenated fuel additive types (MTBE, Bio-ETBE, Bio-ethanol, Bio-butanol), this paper discussed the influence of oxygen contents on gasoline fuel properties and evaporative emission characteristics. Also, this paper assessed the acceleration and power performance of gasoline vehicle for the fuel property.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.58-63
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• 2013

This paper presents a transceiver design for DisplayPort interface using an optical channel. By converting the electronic channel to the optical channel, the DisplayPort's main channel can provide a high-speed data transmission for long distance. The design converting the electronic channel to the optical channel in the main channel and AUX channel of the DisplayPort is presented in this paper. Futhermore, the HPD signal transmission by using AUX channel is proposed. In order to minimize power consumption, this paper also proposed a method of controlling the TX block in the main link. The proposed system is designed by a FPGA and an optical module. The FPGA used 651 ALUT(adaptive look-up table)s, 511 resisters and 324 block memory bits. The maximum operating rate of the FPGA is 250MHz. With the proposed power control scheme, 740mW of power dissipation reduction can be achieved at the main link optical TX module.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.22-28
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• 2015

In order to keep the competitiveness of LPG fuel for transportation fuel, the difference in fuel consumption with gasoline and cost for an aftertreatment system should be reduced with continuous development of technology for LPG engine. In the present study, spray-guided type direct injection combustion system, whose configuration is composed of direct injector in the vicinity of spark plug, was employed to realize stable lean combustion. A certain level of nitrogen oxides($NO_x$) emits due to a locally rich mixture regions in the stratified mixture. With the application of EGR system for the reduction of $NO_x$, 15% of $NO_x$ reduction was achieved whereas fuel consumption and hydrocarbon emission increased. By the application of EGR, the combustion speed reduced especially appeared at initial flame development period and peak heat release rates and increasing rates for heat release rate decreased as EGR rate increased due to the dilution effect of intake air.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.1-7
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• 2015

As the interest on the air pollution is gradually rising up at home and abroad, automotive and fuel researchers have been working on the exhaust emission reduction from vehicles through a lot of approaches, which consist of new engine design, innovative after-treatment systems, using clean (eco-friendly alternative) fuels and fuel quality improvement. This research has brought forward various main issues : whether PM emissions should be regulated for diesel and gasoline vehicles and whether gasoline and LPG powered vehicles can be further neglected from PM emission inventories. Finally, the greenhouse gas regulation has been discussed including automotive emission regulation. The greenhouse gas and emissions of automotive had many problem that cause of ambient pollution, health effects. Based on various test modes and ambient conditions, this paper discusses the characteristics of LPG on exhaust emissions and greenhouse gases. Also, this paper assessed emission characteristics due to the test temperature. These test temperature were performed by dividing the temperature of the test mode and the lowest local temperature in winter. Through this study, the correlation of vehicle test mode and ambient condition, exhaust emission, greenhouse gas emission was analyzed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.3
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• pp.184-196
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• 2020

In this paper, a single-bit 2nd-order delta-sigma modulator with the architecture of cascaded-of-integrator feedforward (CIFF) is proposed for precision measurement of current flowing through a secondary cell battery in a battery management system (BMS). The proposed modulator implements two switched capacitor integrators and a single-bit comparator with peripheral circuits such as a non-overlapping clock generator and a bias circuit. The proposed structure is designed to be applied to low-side current sensing method with low common mode input voltage. Using the low-side current measurement method has the advantage of reducing the burden on the circuit design. In addition, the ±30mV input voltage is resolved by the ADC with 15-bit resolution, eliminating the need for an additional programmable gain amplifier (PGA). The proposed a single-bit 2nd-order delta-sigma modulator has been implemented in a 350-nm CMOS process. It achieves 95.46-dB signal-to-noise-and-distortion ratio (SNDR), 96.01-dB spurious-free dynamic range (SFDR), and 15.56-bit effective-number-of-bits (ENOB) with an oversampling ratio (OSR) of 400 for 5-kHz bandwidth. The area and power consumption of the delta-sigma modulator are 670×490 ㎛2 and 414 ㎼, respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.1
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• pp.128-136
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• 2008

Recently, the unusual climate change is happening from the global warming in the whole world, the Korean peninsula is also no exception. It is predicted by many researchers that, in the near future, the Super-Typhoon of overwhelming power will occur due to rising temperatures on the sea surface around the Korean peninsula. In this study, numerical simulation has been performed with the Super-Typhoons which combined route of Typhoon Maemi with typhoon conditons of Hurricane Katrina (New Oleans in U.S.A, 2005), Typhoon Durian (philippine, 2006) and Typhoon Vera (Ise Bay in Japan, 1959) at Busan and Gyeongnam coastal area which has been badly damaged due to storm surge every year. From the numerical results, it is revealed that the storm surge heights of the Super-Typhoons are higher than that of Maemi, specially the storm surge height in the case of Katrina is about 4 times larger. So, it can be pointed out that the construction of countermeasures against disasters are very important in order to prepare against an attack of the Super-Typhoons.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2003.11a
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• pp.91-92
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• 2003

비태인의 급여(0, 600 ppm)가 사료의 단백질 수준(14, 16 ％)에 따라 산란계의 생산성과 난품질, 혈액성상, 간과 가슴육의 일반성분에 미치는 영향을 구명하기 위하여 83주령 하이라인 산란계 192수를 이용하여 12주간 사양실험을 실시하였다. 기초사료는 에너지 수준이 2,800 kcal/kg, methionine과 lysine, cystine의 수준은 단백질 수준에 비례하도록 하였다. 조사항목으로 산란율과 난중, 사료섭취량, 사료요구율, 계란품질은 4주 간격으로 측정했다. 실험 종료시 복강지방과 혈액중 total protein과 albumin, BUN, triglyceride, total cholesterol, HDL-cholesterol, LDL-cholesterol 함량, 간의 methionine, choline 함량, 간과 가슴육의 수분, 조단백질, 조지방 함량을 측정하였다. 산란율은 단백질 수준에 따라 증가하였으며(P＜0.05) 비태인 급여에 의한 차이는 없었다. 난중은 단백질과 비태인 급여로 증가하였으며(P＜0.05) 산란양은 단백질 수준이 증가할수록 감소하였다(P＜0.05). 비태인 급여로 사료 요구율은 현저하게 개선되었지만(P＜0.05), 계란의 품질은 차이가 없었다. 혈청 total protein은 비태인 급여로 현저히 증가하였으며 특히 단백질 14 ％ 급여구에서 크게 증가하였다(P＜0.05). 복강지방 함량은 단백질 수준과 비태인 급여에 따라 감소하는 경향을 보였다. 가슴육과 간의 조단백질 함량은 사료의 단백질 수준에 따라 증가하였다(P＜0.05). 간의 조지방 함량은 비태인의 급여로 감소하는 경향을 보였다. 간의 methionine 함량은 단백질과 비태인 수준에 따라 증가하는 경향을 보였으며 choline 함량은 비태인의 급여에 의해서만 증가하는 경향을 보였다. 따라서 비태인의 급여는 단백질 수준이 높은 조건에서 산란율을 개선시키고 난중을 증가시키며 사료 요구율을 개선한다.록 산가는 증가하는 것을 볼 수 있다. 홍국주의 전자 공여능에 의한 항산화력은 25.6%, 아질산염 소거능은 27.6%, Total phenolic compound 함량은 12.34mg%, ACE저해작용은 38%의 항산화력을 나타냈다.과 $O_2$와 $CO_2$의 농도에서 평균오차 0.2%로 정밀한 것으로 나타났으며 호흡속도 측정용 챔버의 혼합기체 공급측과 배기측의 가스 농도를 3회 반복 측정한 결과 재현성에서는 0.1%이하의 편차로 나타났다. 개방계 호흡속도 자동 측정 시스템을 이용하여 환경기체조성하에서 토마토의 호흡속도를 측정하는 실측 실험을 수행한 결과 2$0^{\circ}C$에서 12.7~42.1mg$CO_2$/kg.hr였으며 12$^{\circ}C$에서 2.5~8.2mg$CO_2$/kg.hr로 일반적으로 보고되고 있는 토마토 호흡속도와 일치하는 결과를 나타내었다.다.환원당인 sucrose 함량은 계속 증가하였고 fructose, glucose, sorbitol의 함량(추황의 sorbitol을 제외)은 생장이 촉진됨에 따라 증가하다가 다시 점차적으로 감소하였다. 이러한 결과는 총당과 환원당의 측정결과와 일치한 것으로 나타났다. 결론적으로 배의 성장에 따라 산 함량은 감소하였고 당 함량은 증가하였다.luco-pyranoside, quercetin 7-O- -glucopyranoside, acacetin 7-O-$\beta$-D-glucuronide and apigenin-6-C-$\beta$-D-glucopyranosyl-8-C-$\beta$-D-glucopyranoside were first isolated and identified from safflower leaf. Among these flavonoids, luteolin

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.917-930
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• 2018

A quantitative risk assessment method for quantitatively evaluating the fire risk in designing a road tunnel disaster prevention facilities has been introduced to evaluate the appropriateness of a disaster prevention facility in a large tunnel through which all vehicle types pass. However, since the quantitative risk assessment method of the developed can be applied only to the large sectional area tunnels (large tunnels), it is necessary to develop a quantitative risk assessment method for road tunnels passing only small cars which has recently been constructed or planned. In this study, fire accidents scenarios and quantitative risk assesment method for small road tunnels through small cars only which is based on the methods for existing road tunnels (large tunnels). And the risk according to the distance between cross passage is evaluated. As a result, in order to satisfy the societal risk assessment criteria, the distance of the appropriate distance between cross passages was estimated to be 200 m, and the effect of the ventilation system of the large port exhaust ventilation system was quantitatively analyzed by comparing the longitudinal ventilation system.