• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5A
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• pp.517-525
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• 2008

In this paper, we cary out system level simulations to investigate the effect of cell shape(i.e., different base station displacements in the two directions defined by the street grid) on minimizing transmitter power, interference power, and blocking probability for CDMA system in urban microcellular environments. In urban microcell, path loss to the base station depends on the orientation of the street where the mobile is located. Interference from mobile stations to the base station in the reference cell is considered up to second tier. The wrap around method is used to include the second tier interference with realistic computational complexity without reducing the accuracy of interference calculations. The investigation shows that the transmitter power, interference power, and blocking probability in a cell can be reduced by proper selection of the efficient cell shape.

• Korea Trade Review
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• v.47 no.2
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• pp.19-29
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• 2022

This study evaluated the importance of automobile procurement logistics using AHP. Although automobile procurement and logistics is represented by JIT, internal and external risk factors for the automobile and logistics industries are increasing, so it is necessary to re-evaluate them and establish countermeasures. Therefore, this study conducted AHP analysis targeting 30 automobile procurement and logistics experts. Through previous studies and interviews, 4 factors for Tier 1 and 12 factors for Tier 2 were derived. As a result of AHP, the logistics factor was analyzed as the most important and the cost factor was less important than the other factors. This means that supply chain operation is more important than cost, and it is analyzed that stopping all supply chain participants is more damaging than logistics or inventory costs. Such research can provide implications not only for the automotive supply chain but also other industries with similar characteristics, and it is considered to be a meaningful study at the present time when the global supply chain is being reorganized.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.855-863
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• 2016

Most greenhouse gases were arisen from the generation and use of energy, more than about 95 % of greenhouse gas from the traffic section was resulted by the transportation fuels. Also, when using the $CO_2$ emission factor suggested at IPCC G/L, there was the weakness which did not reflect the own property of fuel by country. And most industrialized countries have applied with the $CO_2$ emission factor of Tier 2 or Tier 3 to make the national greenhouse report to submit to UN according to the Kyoto Protocol. In this study, the transportation fuels using in domestic like unleaded gasoline, diesel, etc were analysed to identify the physical/chemical properties and these data were used to calculate the $CO_2$ emission factor of each fuels. And the study analysed the time series analysis to compare the property of fuels according to the change of time.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.383-394
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• 2023

In Korea, the U.S. Tier-4 Final emission standards have been applied to agricultural machinery since 2015. This study was conducted to analyze the emission characteristics of agricultural tractors during plow tillage operations using PEMS (portable emissions measurement systems). The tractor working speed was set as M2 (5.95 km/h) and M3 (7.60 km/h), which was the most used gear stage during plow tillage operation. An engine idling test was conducted before the plow tillage operation was conducted because the level of emissions differed depending on the temperature of the engine (cold and hot states). The estimated level of emissions for the regular area (660 m²), which was the typical area of cultivation, was based on an implement width of 2.15 m and distance from the work area of 2.2 m. As a result, average emission of CO (carbon monoxide), THC (total hydrocarbons), NOx (nitric oxides), and PM (particulate matter) were approximately 6.17×10-2, 3.36×10^-4, 2.01×10^-4, and 6.85×10^-6 g/s, respectively. Based on the regular area, the total emission of CO, THC, NOx, and PM was 2.62, 3.76×10^-2, 1.63, and 2.59×10^-4 g, respectively. The results of total emission during plow tillage were compared to Tier 4 emission regulation limits. Tier 4 emission regulation limits means maximum value of the emission per consumption power (g/kWh), calculated as ratio of the emission and consumption power. Therefore, the total emission was converted to the emission per power using the rated power of the tractor. The emission per power was found to be satisfied below Tier 4 emission regulation limits for each emission gas. It is necessary to measure data by applying various test modes in the future and utilize them to calculate emission because the emission depends on various variables such as measurement environment and test mode.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.101-111
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• 2011

A new MAC protocol, MT-MAC(Multi-Tier Medium Access Control) by name, is proposed for dense sensor networks. Depending on the density of nodes in a virtual cluster, the cluster header performs the splitting to several tiers in nodes of virtual cluster. MT-MAC split the tiers to use modfied-SYNC message after receiving the beacon message from the cluster header. Because only the sensor nodes in the same tier communicate each other, less power is consumed and longer network life time is guaranteed. By a simulation method with NS-2, we evaluated our protocol. In dense nodes environments, MT-MAC protocol shows better results than S-MAC in terms of packet delivery rates throughput and energy consumption.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.151-154
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• 2001

본 연구는 웹 카메라에 적용하기 위한 JPEG2000의 주요 블록인 EBCOT(Embedded Block Coding with Optimized Truncation)의 설계 및 구현에 관한 연구이다. EHCOT 블록은 웨이블렛(wavelet)변환에 의해 분할된 각 sub-band에 존재하는 주위 화소 값들과 상위 bit-plane의 값들에 대한 상호 연관성을 조사하여 context을 추출하고 그 context를 이용하여 엔트로피 부호화(entropy coding)를 수행하는 T1(Tier 1) 블록과 bit-stream을 구성하는 T2(Tier 2) 블록으로 구성된다. 본 논문에서는 JPEG2000에서 전체 압축성능을 좌우하는 EBCOT의 T1 블록을 Synopsys tool을 이용하여 설계하고 구현하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1591-1594
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• 2002

이 논문에서는 기존의 Ad Hoc 네트워크 라우팅 방법 중 proactive routing 과 reactive routing 의 장점을 접목시켜 2-tier 계층구조위에서 효율적인 routing 기법을 제안한다. 또한 제한된 tier-2 네트워크에서 기존의 3GPP 서비스와 상호 연동 가능성을 고려하여 네트워크의 형태 변화에 따른 클러스터 헤더의 효율적인 생성 및 안정적인 경로 확보와 함께 클러스터 헤더의 신뢰성을 제공하기 위한 키 분배 메커니즘을 고찰한다.

• Journal of Information Technology Applications and Management
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• v.24 no.2
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• pp.97-112
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• 2017

This paper aims to research the technology level of sports industry, through analyzing the technology gap between Korea and other major countries (USA, Europe, Japan, and China), and provide a list of technologies to be prioritized for R&D investment by conducting an analysis of the strategic importance of various element technologies. The results of the analysis showed that the technology level of Korean sports industry currently stands at 70.5% of the country with the most advanced technology (the USA), and that the technology gap amounts to 4.8 years. It was also found that the USA is the country with the most advanced technology (100%) at present, followed by Europe (91.1%), Japan (88.3%), Korea (70.5%), and China (61.2%). To reduce the technology gap, we established a Strategic Zone (SZ) and derived three element technologies including 'design and production technologies for sports and game equipment' in the $1^{st}$ tier, nine element technologies including '3D motion analysis and simulation technology' in the $2^{nd}$ tier, and four element technologies including 'fitness/health promotion and management technology' in the $3^{rd}$ tier. The significance of this research is that it included five major technology categories of the sports industry in its analysis, selected an expert on sports industry technologies using the delphi method. Therefore, the results of this study may be suitable for use as basic data in establishing the R&D strategy for the future development of the sports industry.

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.516.1-516.1
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• 2003

• Journal of The Korean Society of Grassland and Forage Science
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• v.43 no.4
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• pp.257-267
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• 2023

The grassland section of the greenhouse gas inventory has limitations due to a lack of review and verification of biomass compared to organic carbon in soil while grassland is considered one of the carbon storages in terrestrial ecosystems. Considering the situation at internal and external where the calculation of greenhouse gas inventory is being upgraded to a method with higher scientific accuracy, research on standards and methods for calculating carbon accumulation of grassland biomass is required. The purpose of this study was to identify international trends in the calculation method of the grassland biomass sector that meets the Tier 2 method and to conduct a review of variables applicable to the Republic of Korea. Identify the estimation methods and access levels for grassland biomass through the National Inventory Report in the United Nations Framework Convention on Climate Change and type the main implications derived from overseas cases. And, a field survey was conducted on 28 grasslands in the Republic of Korea to analyse the applicability of major issues. Four major international issues regarding grassland biomass were identified. 1) country-specific coefficients by land use; 2) calculations on woody plants; 3) loss and recovery due to wildfire; 4) amount of change by human activities. As a result of field surveys and analysis of activity data available domestically, it was found that there was a significant difference in the amount of carbon in biomass according to use type classification and climate zone-soil type classification. Therefore, in order to create an inventory of grassland biomass at the Tier 2 level, a policy and institutional system for making activity data should develop country-specific coefficients for climate zones and soil types.