• Journal of Korean Society for Atmospheric Environment
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• v.27 no.4
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• pp.405-415
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• 2011

The objective of this study was to compare greenhouse gas emissions from road transportation by calculation methods (Tier 1, Teir 2, and Tier 3). Tier 1 based on 2006 IPCC guidelines default emission factor and amount of fuel consumption. The Tier 2 approach is the same as Tier 1 except that country-specific carbon contents of the fuel sold in road transport are used. Tier 2 based on emission factor of guidelines for local government greenhouse gas inventories (Korea Environment Corporation), the fuel consumption per one vehicle, and the registered motor vehicles. The Tier 3 approach requires detailed, country-specific data to generate activity-based emission factors for vehicle subcategories (National Institute of Environmental Research) and may involve national models. Tier 3 calculates emissions by multiplying emission factors by vehicle activity levels (e.g., VKT) for each vehicle subcategory and possible road type. VKT was estimated by using GIS road map and traffic volume of the section. The GHG average emission rate by the Tier 1 was 728,857 $tonCO_2eq$/yr, while Tier 2 and Tier 3 were 864,757 $tonCO_2eq$/yr and 661,710 $tonCO_2eq$/yr, respectively. Tier 3 was underestimated by 10.1 and 20.7 percent for the GHG emission observed by Tier 1 and Tier 2, respectively. Based on this study, we conclude that Tier 2 is reasonable GHG emissions than Tier 1 or Tier 3. But, further study is still needed to accurate GHG emission from Tier 3 method by expanding the traffic survey area and developing the model of local road traffic.

• Journal of Climate Change Research
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• v.1 no.1
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• pp.13-20
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• 2010

Recently, the operation of construction equipments have increased by many construction project. So a respectable amount of greenhouse gas is expected from construction equipments. But the greenhouse gas emissions from construction equipment have been high uncertainty due investigation of a lack of activity data and emission factors in Korea. In this study, annual greenhouse gas emissions from construction equipment are estimated by IPCC's Tier 2 and Tier 3 method. These methods require emission factors, fuel consumption, average kilowatts and operating hours. As the results, the nationwide emission from construction equipments by Tier 2 and Tier 3 are calculated as $21,784kton-CO_2eq/year$ and $22,811kton-CO_2eq/year$ in 2008.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.219-228
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• 2014

Objectives: The major objective of this study was to develop a tier 2 exposure model combining tier 1 exposure model estimates and worker monitoring data and suggesting narrower exposure ranges than tier 1 results. Methods: Bayesian statistics were used to develop a tier 2 exposure model as was done for the European Union (EU) tier 2 exposure models, for example Advanced REACH Tools (ART) and Stoffenmanager. Bayesian statistics required a prior and data to calculate the posterior results. In this model, tier 1 estimated serving as a prior and worker exposure monitoring data at the worksite of interest were entered as data. The calculation of Bayesian statistics requires integration over a range, which were performed using a Riemann sum algorithm. From the calculated exposure estimates, 95% range was extracted. These algorithm have been realized on Excel spreadsheet for convenience and easy access. Some fail-proof features such as locking the spreadsheet were added in order to prevent errors or miscalculations derived from careless usage of the file. Results: The tier 2 exposure model was successfully built on a separate Excel spreadsheet in the same file containing tier 1 exposure model. To utilize the model, exposure range needs to be estimated from tier 1 model and worker monitoring data, at least one input are required. Conclusions: The developed tier 2 exposure model can help industrial hygienists obtain a narrow range of worker exposure level to a chemical by reflecting a certain set of job characteristics.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.87-89
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• 1999

인터넷과 웹 환경이 발달함에 따라 다양한 종류의 웹 응용프로그램들이 개발되고 있다. 최근에 개발되고 있는 웹 기반의 데이터베이스 시스템은 웹 데이터베이스 액세스를 위한 클라이언트 프로그램의 설치 없이 웹 브라우저만으로 데이터베이스를 액세스할 수 있는 장점을 갖고 있다. 기존의 많은 웹 기반 데이터베이스 시스템들은 클라이언트/서버의 2-Tier 구조를 가진다. 그러나 2-Tier 구조는 사용자 수의 증가에 따라 데이터베이스가 존재하는 서버에 과부하가 발생할 수 있다는 단점이 있다. 본 논문은 2-Tier 구조의 문제점을 해결하기 위한 3-Tier 구조의 웹 데이터베이스를 제시한다. 3-Tier 구조는 클라이언트 시스템과 서버 시스템간에 데이터베이스에 관련된 트랜잭션(transaction)처리와 사용자 관리를 위한 중간 시스템이 존재하는 구조이다. 3-Tier 구조는 사용자가 데이터베이스를 액세스할 때 중간시스템을 거쳐 서버로 연결되도록 함으로써 2-Tier 구조에서 발생할 수 있는 서버 과부하를 해결한다.

• Journal of the Korea Society of Computer and Information
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• v.9 no.3
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• pp.45-53
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• 2004

The fact that the end-user response time could become unacceptable in the 2-tier C/S system has been well known to C/S system developers. But inexperienced new developers who want to provide mobile solutions using PDA sometimes do not realize the ominous consequences of the 2-tier C/S systems. Except for the easy of development. the 2-tier C/S system has many weak points like in application deployment, security, scalability, application reuse, heterogeneous DBMS support, availability. and response time. This paper analyzes the response time in the 2-tier and 3-tier C/S systems through simulation. Although the problem space is confined to the 2 and 3 tiers, the result could be equally applied to any multi-tier systems.

• Journal of Korea Multimedia Society
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• v.15 no.2
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• pp.266-272
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• 2012

Multilingual support of software is necessary for entering global market. 3-tier architecture is a solution for problems of 2-tier architecture. It divides an application into a client-tier and an application-tier, and presentation logic and database are connected by middleware. The advantage of 3-tier architecture is the enhanced performance through load balancing, scalability, easier maintenance and reusability. This paper proposes a multilingual support method that utilizes common resource files for 3-tier enterprise softwares, applies the proposed method to development of multilingual version of billing solution, and verify the usefulness of it. It is easy for development and maintenance of software, the addition of language supported. Proposed method holds a resource file for each language and provides a multilingual support class library. Therefore this method reduces a waste of memory and disk space. Deployment of a class library into an application tier makes development and maintenance of software, the addition of new language supported easy. To avoid inappropriate modification of a resource file, a multilingual support class library is provided in a dll file.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.4
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• pp.1481-1500
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• 2016

Device-to-Device (D2D) communication underlaying macro-small cell networks, as one of the promising technologies in the era of 5G, is able to improve spectral efficiency and increase system capacity. In this paper, we model the cross- and co-tier D2D communications in two-tier macro-small cell networks. To avoid the complicated interference for cross-tier D2D, we propose a mode selection scheme with a dedicated resource sharing strategy. For co-tier D2D, we formulate a joint optimization problem of power control and resource reuse with the aim of maximizing the overall outage capacity. To solve this non-convex optimization problem, we devise a heuristic algorithm to obtain a suboptimal solution and reduce the computational complexity. System-level simulations demonstrate the effectiveness of the proposed method, which can provide enhanced system performance and guarantee the quality-of-service (QoS) of all devices in two-tier macro-small cell networks. In addition, our study reveals the high potential of introducing cross- and co-tier D2D in small cell networks: i) cross-tier D2D obtains better performance at low and medium small cell densities than co-tier D2D, and ii) co-tier D2D achieves a steady performance improvement with the increase of small cell density.

• Journal of Climate Change Research
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• v.1 no.1
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• pp.51-57
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• 2010

Recently the number of motorcycles has increased in urban area, and it is believed that motorcycle is one of the air pollution and greenhouse gas emission sources. But the greenhouse gas emission from motorcycle has been high uncertainty due investigation of a lack of activity data and emission factors in Korea. So in this study, the greenhouse gas emission from motorcycle is estimated by considering the population of moped and VKT(vehicle kilometers travelled) of motorcycle by recent other studies. And the emissions by IPCC Tier 2 and Tier 3 methodology are calculated and compared. As the results, the nationwide $CO_2$ equivalent emissions from motorcycles by Tier 2 and Tier 3 method are calculated as 2,758 kton/yr and 2,739 kton/yr in 2008. The contribution ratio of this emission is estimated as 2.7% in on-road transport sector.

• Journal of Animal Science and Technology
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• v.45 no.6
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• pp.997-1006
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• 2003

This study was conducted to investigate the national methane emission from livestock enteric fermentation. For methane emission estimation, livestock were mainly categorized to cattle, swine, poultry, sheep, goats and horses, and cattle were further sub-categorized to calves, fattening cattle, breeding cows in Hanwoo and calves, fattening cattle and lactating cows in dairy cattle. Tier 2 methane emission factors were deduced based on the characteristics of animal performances, live weight, slaughter weight, daily weight gain, and feed digestibility in each category. Tier 2 emission factors of Hanwoo range from 39 to 49 kg/head/year and it is similar to that of Tier 1(47kg/head/year). Tier 2 emission factor of dairy cattle was 107 kg/head/year and it is slightly lower than that of Tier 1(118kg/head/year). Total methane emission from livestock enteric fermentation by Tier 2 method was estimated to be 126.8 tones in 2001. The methane emissions by Hanwoo, dairy cattle, swine, goats, horses and sheep were 61.70, 47.76, 13.08, 2.25, 0.17 and 0.01 tones, respectively. By the use of Tier 2 method instead of Tier 1, the accuracy and reliability of methane emission estimates from livestock enteric fermentation in Korea is considered to be improved.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.4
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• pp.454-465
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• 2012

The Korean government decided to reduce 30% of GHG (greenhouse gas) emissions BAU in 2020. Since many efforts to reduce emissions are urgently needed in Korea, the central administrative organization urges local governments to establish their own reduction schemes. Among many GHG emission categories, the emission from mobile source in Gyeonggi Province accounted for 25.3% of total emissions in 2007 and further the emission from road transport sector occupied the most dominant portion in this transportation category. The objective of this study was to compare 3 types of GHG emissions from road transport sector in 31 local cities/counties of Gyeonggi Province, which have been estimated by Tier 1, Tier 2, and Tier 3 methodologies. As results, the GHG emission rates by the Tier 1 and Tier 2 were $19,991kt-CO_2\;Eq/yr$ and $18,511kt-CO_2\;Eq/yr$, respectively. On the other hand, the emission rate by Tier 3 excluding a branch road emission portion was $18,051kt-CO_2\;Eq/yr$. In addition, the total emission rate including all the main and branch road portions in Gyeonggi Province was $24,152kt-CO_2\;Eq/yr$, which was estimated by a new Tier 3 methodology. Based on this study, we could conclude that Tier 3 is a reasonable methodology than Tier 1 or Tier 2. However, more accurate and less uncertain methodology must be developed by expanding traffic survey areas and adopting a suitable model for traffic volumes.