• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 C
• /
• pp.1506-1509
• /
• 1999

This paper presents a new economic dispatch algorithm to improve the unit commitment solution while guaranteeing the near optimal solution without reducing calculation speed. The conventional economic dispatch algorithms have the problem that it is not applicable to the unit commitment formulation due to the frequent on/off state changes of units during the unit commitment calculation. Therefore, piecewise linear iterative method have generally been used for economic dispatch algorithm for unit commitment. In that method, the approximation of the generator cost function makes it hard to obtain the optimal economic dispatch solution. In this case, the solution can be improved by introducing a inverse of the incremental cost function. The proposed method is tested with sample system. The results are compared with the conventional piecewise linear iterative method. It is shown that the proposed algorithm yields more accurate and economical solution without calculation speed reduction.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.357-362
• /
• 2000

Allowable stress design(ASD) method has been widely used to design steel structures such as boiler and heat recovery steam generator(HRSG) of power plant. However, many researchers are recently intrested in road and resistance factor design(LRFD) method which may take the place of ASD. In this work, the weight calculation of steel structure was compared when ASD and LRFD were applied respectively. For the calculation of weight of steel structure, computer program was developed and applied to obtain beam weight. Using this program and GTSTRUDL, structural design program, weight of steel structure is calculated. As a result of weight calculation, maximum 5.4% of weight reduction is achieved among examples of this study by applying LRFD comparing with the result of ASD, and those results quite dependent on the applied load and member classification.

• 전자공학회논문지B
• /
• 제33B권3호
• /
• pp.126-132
• /
• 1996

In this paper, the complexity reduction method for QCELP speech coder (IS-96) without any perfomrance degradation is proposed for the vecoder of CDMA digital cellular system. The energy terms in pitch parameter search and codebook search routines that require large computations are calculated recursively by utilizing the overlapped structure of code vectors in adaptive codebook and excitation codebook. The additional complexity reduction in the codebook search routine can be achieved by using a simple form in calculation of the energy term when the initial codebook value is zero. In the case of lower transmission rates such as 4,2,1 kbps, the complexity reduction by recursive calulations of energy term is increased.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 1998년도 유체기계 연구개발 발표회 논문집
• /
• pp.240-247
• /
• 1998

Leakage vortices formed near blade tip causes an increase of total pressure loss near casing endwall region and as a result, the efficiency of rotor decreases. The reduction of rotor efficiency is related to the size of tip clearance. In this study, the three-dimensional flowfields in an axial flow rotor were calculated with varying tip clearance under various flow rates, and the numerical results were compared with experimental ones. The effects of tip clearance and attack angle on the leakage vortex and overall performance, and the less distributions were investigated through numerical calculations. In this study, tip leakage flow rate and total pressure loss by tip clearance were evaluated using numerical results and aprroximate equations were presented to evaluate the reduction of rotor efficiency by tip leakage flow.

• 한국유체기계학회 논문집
• /
• 제2권1호
• /
• pp.73-80
• /
• 1999

Leakage vortices formed new blade tip causes an increase of total pressure loss near the casing endwall region and as a result, the efficiency of rotor decreases. The reduction of rotor efficiency is related to the size of the tip clearance. In this study, the three-dimensional flowfields in an axial flow rotor were calculated by varying the tip clearance under various flow rates, and the numerical results were compared with experimental ones. The effects of tip clearance and attack angle on the leakage vortex and overall performance, and the loss distributions were investigated through numerical calculations. In this study, tip leakage flow rate and total pressure loss by tip clearance were evaluated using numerical results and approximate equations were presented to evaluate the reduction of rotor efficiency by tip leakage flow.

• KIEAE Journal
• /
• 제11권4호
• /
• pp.87-94
• /
• 2011

This study was suggested to develop sustainable durability design system and proposed the plan to evaluate design conditions that meet the intended service life and $LCCO_{2}$ reduction level of reinforced concrete structure easily from the early design stage. For that the W/B and covering depth of the concrete structure were calculated through calculation of service life based on standard specification expression and the quantitative reduction rate of the vertical member of reinforced concrete structure by the calculated W/B was applied. Life cycle of building classified into construction stage, operation stage, maintenance stage, and demolition/disposal stage and the method of $CO_{2}$ evaluation of each stage was proposed. For construction stage, the major construction materials that take up over 80% $CO_{2}$ emitting during building construction were selected and the $CO_{2}$ evaluation method for 5 standard apartment houses was proposed. Also, for operation stage, $CO_{2}$ emission was calculated through calculation of heating load by energy efficiency rating certification system. For maintenance stage, $CO_{2}$ emission was calculated using concept of re-construction by life and for demolition/disposal stage was calculated with the use of construction standard estimate. As a result of the case study by such evaluation methods, 80 years of service life and 17 specifications of sustainable durability design that meet the 40% intended $LCCO_{2}$ reduction level were deduced. The Maximum $LCCO_{2}$ reduction rate was analyzed by 47.2%.

• 한국항공우주학회지
• /
• 제41권11호
• /
• pp.855-864
• /
• 2013

능동 탭은 BVI 소음 저감을 위한 능동제어 기술 중 하나이며, 이를 이용한 소음 저감효과에 대한 해석은 기술 개발에 있어서 매우 중요한 과정의 하나이다. 능동 탭의 소음저감 성능 분석을 위하여 모델 로터시스템에 대한 구조 설계를 수행하고 CFD 해석을 통해 에어포일 공력 데이터를 생성하였으며, 이를 이용하여 통합해석 프로그램인 CAMRAD II 모델을 구성하였다. 하강 비행 상태에서 능동 탭을 HHC 방법으로 작동할 경우 로터에서 발생되는 공력 하중을 CAMRAD II를 이용하여 계산하고, 이에 따른 BVI 소음 변화를 자체 소음해석 프로그램으로 계산하였다. 능동 탭의 작동 길이 및 제어 위상의 변화에 따른 소음해석 결과 최대 -3.3dB의 BVI 소음 저감 효과를 얻을 수 있었다.

• 한국농공학회논문집
• /
• 제65권5호
• /
• pp.69-80
• /
• 2023

Carbon neutrality in agriculture can be derived from systematic GHG reduction policies based on quantitative environmental impact analysis of GHG-emitting activities. This study is to explore how to advance the calculation of carbon emissions from agricultural activities to the detailed spatial level to a spatial Tier 3 level (Tier 2.5 level), methodologically beyond the Tier 2 approach. To estimate the GHG emissions beyond the Tier 2.5 level by region for detailed spatial units, we constructed available activity data on carbon emission impact factors such as rice cultivation, agricultural land use, and livestock. We also built and verified detailed data on emission activities at the field level through field surveys. The GHG emissions were estimated by applying the latest national emission factors and regional emission factors according to the IPCC 2019 GL based on the field-level activity data. This study has significance that it explored ways to build activity data and calculate GHG emissions through statistical data and field surveys based on parcels, one of the smallest spatial units for regional carbon reduction strategies. It is expected that by utilizing the activity data surveyed for each field and the emission factor considering the activity characteristics, it will be possible to improve the accuracy of GHG emission calculation and quantitatively evaluate the effect of applying reduction policies.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.1315-1319
• /
• 2011

As government's policy is enacted to reduce greenhouse gas emission in transportation sector, railroad sector has to estimate amount of emission and propose feasible methods to reduce emission. To calculate accurate emission of railroad sector, we performed a study on the calculation model development for Tier 3 GHG emission factors. According to IPCC guide line, Tier 3 emission factor reflects individual characteristic of diesel locomotive. For this reason, we estimated GHG emission factor by stratified diesel locomotive and the result show difference of emission factor by notch changing. Therefore, the analysis of notch frequency during operation is required to develop Tier 3 emission factor, and we analysed a running pattern of diesel locomotive. As a result, idle and 8 notch consist about 70% of total running distance. In conclusion, the calculation model suppose that Tier 3 GHG emission factor is the sum of multiplied emission factor by weights in each notch. This result can contribute to Tier 3 emission factor calculation and reduction method development of emission in railroad sector by managing driving efficiency and technology development.

• 한국광학회지
• /
• 제10권5호
• /
• pp.405-412
• /
• 1999

SSF 알고리즘의 고정된 구간을 개선하여 자동으로 구간을 선택함으로 계산시간을 줄인 Auto Z-step과, SSF 알고리즘에 사용되는 FFT 방법의 표본값을 자동적으로 줄여서 계산시간을 감소시킨 Auto T-step 알고리즘을 제안하였다. 2.5Gbps 100km 전송시 이 두 알고리즘을 사용한 것은 기존의 1km fixed step 알고리즘보다 1/120의 계산시간이 줄었고, 10Gbps 40km 전송시 최대 1/56으로 줄었으며, 오차는 모두-30㏈ 이하였다. eye diagram으로 kkm fixed step 알고리즘과 비교할 때 오차가 무시될 수 있음을 알 수 있었다.