• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.6
• /
• pp.558-567
• /
• 1997

Linear power amplifier modules with high-efficiency have been developed for PCS handy phone. These modules were designed using extracted large-signal models of MESFETs and harmonic balance simulation. The modules are intended for low-tier and high-tier at the operation frequency range of 1750 ~ 1780 MHz. For low-tier module, the output power and $IMD_3$ were 23.2 dBm and 31 dBc, respectively, at power-added efficiency of 34% with the supply drain bias of 3.6 V. For high-tier module, the output power and $IMD_3$ were 272.2 dBm and 31 dBc, respectively, at power-added efficiency of 33% with the supply drain bias of 4.2 V. These linear power amplifier modules are suitable for PCS handy phone.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2009.10a
• /
• pp.295-296
• /
• 2009

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2003.11a
• /
• pp.217-218
• /
• 2003

지구의 기후변화는 자연, 인위적인 요인 모두에 의해서 발생되지만 UN IPCC는 "인간의 활동에 의해 발생되는 온실가스가 자연적인 기후변화에 단독으로 미치는 영향보다도 복합적으로 작용하여 현재보다 휠 씬 더 지구온난화 등 기후변화를 가속화시키고 있다"고 하여 인위적인 요인의 중요성을 시사하고 있으며, 인위적 온실가스 배출량의 상당부분은 에너지산업, 제조/건설업, 수송 등의 연료연소부문에서 기인하고 있다. (중략)

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.10 no.5
• /
• pp.105-112
• /
• 2011

Delay reduction of vehicles at the intersection is highly dependent on the signal operation method. Improper traffic operation causes the violation of the traffic regulations and increasing traffic congestion. Delay because of congestion has contributed to the increase in carbon dioxide in the atmosphere. The focus of this paper is to measure the amount of carbon dioxide when the intersection is changed to roundabout. Even though, Intergovernmental Panel on Climate Change(IPCC) recommends Tier 1 method to measure the amount of greenhouse gas from vehicles, this paper used Tier 3 method because we could use the data of average running distance per each vehicle model. Two signalized intersections were selected as the study area and the delay reductions of roundabout operation were estimated by VISSIM microscopic simulation tool. The control delay for boksu intersection reduced from 28.6 seconds to 4.4 seconds and the KRIBB intersection sharply reduced from 156.4 seconds to 23.6 seconds. In addition, carbon dioxide for two intersections reduced to 646.5 ton/year if the intersection is changed to roundabout. Future research tasks include testing the experiment for networks, as well as for various intersection types.

• Journal of The Korean Association For Science Education
• /
• v.18 no.4
• /
• pp.643-650
• /
• 1998

In order to assess students' higher mental abilities, such as scientific inquiry thinking skills, the essay type items would be more adequate than the multiple choice itmes. However, due to the present condition in which a huge number of students take the examination at the same time, it is inevitable to use the multiple choice type. For this reason, it is necessary to develop a new type of multiple choice items which can reduce the disadvantages of the traditional multiple choice type and can achieve a similar level of validity as subjective type assessment. The three-tier multiple choice test items which can be used for a large sample of students and especially for scientific inquiry thinking abilities, are proposed and examined. The three-tier multiple choice test items asked firstly conclusion or the results of calculation or experimental apparatus, secondly the processes of calculation or of developing conclusion, thirdly asking relevant scientific concepts. For the item analysis, 1 point was given to the correct answer, while 0 point was given to the wrong one. The data were processed through the computer program developed in Turbo C 2.0 language with an IBM compatable personal computer. The average score in the sub-items asking for scientific concepts was lower than that in the sub-items asking for results or processes. The score of guessing by chance in the three-tier multiple choice items was only 0.13%, so that the probability of making correct answers by just guessing would be extremely low. The three-tier multiple choice items, even if they are objective items, are thought to assess thinking skills of the scientific inquiry meaningfully excluding the possibility of guessing by chance.

• Korean Journal of Construction Engineering and Management
• /
• v.14 no.2
• /
• pp.78-86
• /
• 2013

The researches for reduce $CO_2$ are going along animatedly in hole industry area. In construction area, the researches to minimize $CO_2$ emission are progressing variously. The researches to minimize $CO_2$ emission based on $CO_2$ emission. The method measuring $CO_2$ emission are using $CO_2$ emission coefficient on fuel consumption, LCA and an inter-industry relation table. Especially, the methods using the carbon emission coefficient based on fuel consumption are 3 types(Tier1~Tier3) of IPCC. Present, the most using method(Tier1) is using the fuel consumption and the carbon emission coefficient. But because this method do not effect each vehicle distance and driving environment, we can't calculate right $CO_2$ emission. Especially construction project's $CO_2$ emission could be different by project's characteristic. However, we can't apply these difference with present methods. So we need methodology calculating $CO_2$ emission by applying personal project's characteristic and these methodology's most important things is directly measuring $CO_2$ emission of construction equipment which use energy. The object of this study is to develop the $CO_2$ emission calculation methodology which occur in construction process, is to suggest ways to measure in real time $CO_2$ emission from construction equipment.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.2
• /
• pp.98-104
• /
• 2011

The introduction of a diesel engine into the passenger car and light duty applications in the United States involves significant technical challenges for the automotive makers. This paper describes the SCR System optimization procedure for such a diesel engine application to meet Tier2 Bin5 emission regulation. A urea SCR system, a representative $NO_x$ reduction after-treatment technique, is applied to a 3.0 liter diesel engine. To achieve the maximum $NO_x$ reduction performance, the exhaust system layout was optimized using series of the computational fluid dynamics and the urea distribution uniformity test. Furthermore a comprehensive simulation model for the key factors influencing $NO_x$ reduction performance was developed and embedded in the Simulink/Matlab environment. This model was then applied to the urea SCR system and played a key role to shorten the time needed for SCR control parameter calibration. The potential of a urea SCR system for reducing diesel $NO_x$ emission is shown for FTP75 and US06 emission standard test cycle.

• Journal of Climate Change Research
• /
• v.6 no.3
• /
• pp.175-184
• /
• 2015

In this study GC and PAS were used to calculate $N_2O$ concentration of exhaust gas from Wood Chip combustion system. Fuel supplied to the incinerator was collected and analyzed and then the analysis result was used to calculate $N_2O$ emissions. Tier 3 and Tier 4 Method were used to calculate the $N_2O$ emissions. Plant's Specific emission factor of $N_2O$ by Tier 3 Method was 0.35 kg/TJ, while default emission factor of Wood?Wood Waste proposed by 2006 IPCC G/L was 4 kg/TJ. So the $N_2O$ emission factor of this study was 3.65 kg/TJ lower compared to the IPCC G/L. The total emissions calculated by Plant's specific emission factor was 4.22 kg during the measuring period, but by Tier 4 Method it was 7.88 kg. This difference in emissions was caused by the difference of continuous measuring and intermittent sampling. It would be necessary to apply continuous measuring to calculate emissions of $Non-CO_2$ gas whose the density distribution is relatively high. However currently, according to the target management guideline of greenhouse gas and energy, the continuous measuring method to calculate greenhouse gas emission is applied only to $CO_2$. Therefore for reliable greenhouse gas emission calculation it would be necessary to apply continuous measuring to calculate $Non-CO_2$ gas emission.

• Journal of Advanced Navigation Technology
• /
• v.13 no.1
• /
• pp.68-73
• /
• 2009

Recently, various services through the Internet are gradually increased and developed. The traditional way of examination has been replacing by the online test as well. The most representative is the IBT TOEFL by the ETS in the US. Besides this, a lot of online tests and some related discussions are very fierce to carry out due to the continuous increase of the number of exam candidates. Taking account of the economic issues compared to the previous test, this online method has a lot of strengths. This paper aims to build an online test system based on the 3- tier browser-server architecture, which is different from the commonly used 2-tier based system. This system was achieved using the Visual Studio.Net 2005 and SQL Server 2000 as development tools, and based on the ASP.NET 2.0 platform, using the ADO.NET and C# language.

• Environmental and Resource Economics Review
• /
• v.23 no.2
• /
• pp.249-280
• /
• 2014

IPCC requires the national uncertainties which show how credible the emission of greenhouse gases is. But the Korean government did not submit the total uncertainties, only the detailed uncertainties by items. Also it uses the default values of IPCC including some missing values. This paper tries to estimate the total uncertainties of energy by categories, which accounts for 85.3% in national emission of greenhouse gases. Concretely, it uses Tier 1 method suggested by IPCC. As a result of the analysis, the uncertainties in energy category are 3.4% similar to Finland's. But there was a big difference among greenhouse gases; carbon dioxide 2.7%, methane 116% and nitrous oxide 473%. So this paper suggests Korean government need to improve not only the activity but also the emission factor of data in order to reduce the national uncertainties in energy category.