• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2005.05a
• /
• pp.348-352
• /
• 2005

본 논문은 조선소에서 계획기간동안 각 플랜트의 생산일정에 따른 블록의 모든 수송요구량이 미리 알려져 있는 정적인(static) 수송환경을 고려한 트랜스포터 일정계획문제를 다룬다. 조선소 내에서 블록들의 수송은 몇 가지 특성을 가진다. 500톤을 초과하는 거대 블록들은 2대 이상이 결합된 새로운 형태의 트랜스포터를 이용하여 운반된다. 운반이 요구되는 블록들 중 일부는 계획기간동안 규정된 출발요구시각에 pick-up되기를 요구하는 반면 나머지 블록들은 계획기간동안 규정된 도착요구시각 전에 delivery되기를 요구한다. 이러한 트랜스포터의 결합 및 시간 제약은 문제를 더욱 복잡하게 하는 요인이 된다. 본 논문에서는 계획기간 내에 모든 블록운반 요구사항들(출발지와 도착지, pick-up과 delivery 시각, 톤수, 결선 등)을 만족시키는 트랜스포터 일정계획문제를 다룬다. 트랜스포터 일정계획문제에서 중요한 주제는 총 로지스틱스 시간 (공차운행시간, delay 시간 및 tardy 시간)을 최소화하기 위해 계획기간 내에 최소의 트랜스포터 운영대수로 각 트랜스포터에 어떤 블록을 할당하고 어떤 순서로 운반할 것인 지를 결정하는 것이다. 이에 본 논문에서는 주어진 트랜스포터 일정계획문제를 해결하기 위해, 1단계에서 최소비용 네트워크 흐름문제를 근간으로 트랜스포터의 최소사용대수를 구하고 이를 기초로 2단계에서 각 트랜스포터에의 블록 할당과 운반순서를 결정하는 2단계 휴리스틱 알고리즘을 제안한다.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.3B
• /
• pp.3-13
• /
• 1999

The diffusion characteristics of the high temperature and salinity water discharged in Chinhae Bay under BMP(Barge-Mounted Plants) desalination processes were simulated to access environmental impact. The 3-D baroclinic flow model is formulated by integrating the basic equations with respect to each control volume and by transforming them into a finite difference form using the space-staggered grid system. With a 3-D baroclinic flow model, the tide-induced and density-induced current was computed and confirmed by comparing with observed data. From the results of numerical experiment, it is expected that the maximum diffusion lengths of the high temperature and salinity which increase $0.6^{circ}C$ and 0.2 after discharging are 1 km and 3.5km, respectively. It may be expected that the discharge has an effect on surrounding area of discharge, but not an effect on whole area of Chinhae Bay.

• The KSFM Journal of Fluid Machinery
• /
• v.6 no.3 s.20
• /
• pp.28-35
• /
• 2003

This paper presents analysis results for the effect of power control strategies on the part load performance of gas turbine based power generation systems utilizing exhaust heat of the gas turbine such as combined cycle power plants and regenerative gas turbines. For the combined cycle, part load efficiency variations were compared among different single shaft gas turbines representing various technology levels. Power control strategies considered were fuel only control and IGV control. It has been observed that gas turbines with higher design performances exhibit superior part load performances. Improvement of part load efficiency of the combined cycle by adopting air flow modulation was analyzed and it was concluded that since the average combined cycle performance is affected by the range of IGV control as well as its temperature control principle, a control strategy appropriate for the load characteristics of the individual plant should be adopted. For the regenerative gas turbine, it is likewise concluded that maintaining exhaust temperature as high as possible by air flow rate modulation is required to increase part load efficiency.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.6
• /
• pp.609-617
• /
• 2011

There is a trend towards the progressive use of higher operating temperatures and stresses to achieve improved efficiencies in power-generation equipment. It is important to perform the crack assessment under hightemperature and high-pressure conditions. The C(t)-integral is a key parameter in crack assessment for transient creep states. The estimation of the C(t)-integral is complex when considering the mechanical and thermal loads simultaneously. In this paper, we study estimation of C(t)-integral under combined mechanical and thermal load depending on loading conditions.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.5
• /
• pp.741-750
• /
• 2011

A pilot-scale biofilter was constructed to discover degradation characteristics of the complex odor discharged from Ansan wastewater treatment plant. Candida tropicalis for volatile organic compounds, sulfur oxidizing bacteria(SOB) for hydrogen sulfide, and bacteria extracted from feces soil were immobilized on a polymer gel media. According to this study, the EBCT was varied from 36 sec to 18 sec. Toluene was removed as 80% along the variations, but it was recovered as 100% within 1 week. All benzene and xylene were removed during the operation while the efficiency of hydrogen sulfur was temporary decreased at 18 sec of EBCT, thereafter it was recovered to 100% within a week. The maximum elimination capacities of the benzene, toluene, xylene, and hydrogen sulfur were 6.6 g/$m^{3}$/hr, 31.7 g/$m^{3}$/hr, 7.8 g/$m^{3}$/hr, and 133.6 g/$m^{3}$/hr, respectively. There were merits on removal both organic and inorganic complex odor using the pilot-scale biofilter embedded with microorganisms immobilized on polymer gel media.

• Transactions of the Korean hydrogen and new energy society
• /
• v.23 no.3
• /
• pp.264-273
• /
• 2012

In this paper, two types of integrated gasification combined cycle (IGCC) plants using either an air separation unit (ASU) or an ion transport membrane (ITM), which provide the oxygen required in the gasification process, were simulated and their thermodynamic performance was compared. Also, the influence of adopting a pre-combustion $CO_2$ capture in the downstream of the gasification process on the performance of the two systems was examined. The system using the ITM exhibits greater net power output than the system using the ASU. However, its net plant efficiency is slightly lower because of the additional fuel consumption required to operate the ITM at an appropriate operating temperature. This efficiency comparison is based on the assumption of a moderately high purity (95%) of the oxygen generated from the ASU. However, if the oxygen purity of the ASU is to be comparable to that of the ITM, which is over 99%, the ASU based IGCC system would exhibit a lower net efficiency than the ITM based system.

• Journal of the Society of Naval Architects of Korea
• /
• v.58 no.6
• /
• pp.431-439
• /
• 2021

The Carbon Fiber Reinforced Plastic (CFRP) material is recently widely used in the composite industry with excellent rigidity and lightweight properties. A ship shaft system requires high standards of safety on torsional strength capacity. The purpose of this study is to verify the applicability of a CFRP shaft system to take the place of metal shaft systems for ships from a viewpoint of torsional strength. Selection of materials and manufacturing method are executed then two geometrically scaled CFRP shaft system models were designed and manufactured with three-layer patterns. The models were used for a series of torsion tests under single and repeated torsional loading conditions. Detailed design and manufacturing methods for a CFRP ship shaft system are documented and the torsion test results are listed in this paper. The results of this study could be useful guidelines on the development of CFRP ship shaft systems and a test method.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.8
• /
• pp.639-648
• /
• 2013

This paper describes on the NOx/CO emission characteristics, temperature characteristics and flame structures when firing coal derived synthetic gas especially for gases of Buggenum and Taean IGCC. These combustion characteristics were observed by conducting ambient-pressure elevated-temperature combustion tests in GE7EA model combustor when varying heat input and nitrogen dilution ratio. Nitrogen addition caused decrement in adiabatic flame temperature, thus resulting in the NOx reduction. At low heat input condition, nitrogen dilution raised the CO emission dramatically due to incomplete combustion. These NOx reduction and CO arising phenomena were observed at certain flame temperature of $1500^{\circ}C$ and $1250^{\circ}C$, respectively. As increasing nitrogen dilution, adiabatic flame temperature and combustor liner temperature were decreased and singular points were detected due to change in flame structure such as flame lifting. From the results, the effect of nitrogen dilution on the NOx/CO and flame structure was examined, and the test data will be utilized as a reference to achieve optimal operating condition of the Taean IGCC demonstration plant.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.76.2-76.2
• /
• 2011

석탄으로부터 합성석유를 생산하는 상용기술을 도입하여 건설하고 이와 더불어 원천기술 개발을 위한 국산화 기술 개발을 병행하여 향후 고유가 시대를 대비한 국가 에너지 안보 확립과 국내 기술 개발의 가속화를 추구해야 할 필요성이 대두되고 있다. 본 타당성 조사는 3종류의 석탄(호주 Wyong탄, 인도네시아 NTC탄, 인도네시아 KBB탄)으로부터 가스화에 의하여 합성석유스를 생산하는 공정에 대한 타당성 조사(Feasibility Study, FS)를 Class 5(하한 -50~-20%, 상한 30~100%)의 정확도로 수행하는 것을 내용으로 하고 있다. 플랜트의 규모는 합성석유 기준으로 20,000배럴/일이다. 플랜트의 건설을 위해서 광양제철소 슬래그처리장 내 12만평 부지에 조성 중인 포스코 SNG 생산공장 부지의 일부를 사용하는 것을 기준으로 하였다. 일반적으로 석탄의 종류에 따라서 가스화기의 종류 및 성능이 결정된다. 본 타당성 조사 연구에서 선정된 3종류의 석탄의 조성, 발열량, 회분 함량 등의 특성을 고려하여 각각의 석탄에 적합한 현존하는 상용급 가스화기를 선정하였다. 해당 석탄이 가스화기 종류에 따라 적절한 전처리 과정(건조, 분쇄, 슬러리화)을 거친 후 가스화기에 공급되는 것을 가정하여 석탄의 원소분석 조성, 발열량, 회분함량, 회분조성, 회 용융점 등의 변수에 따라서 각각 해당 가스화기에서 가스화되었을 때의 생성되는 합성가스의 조건을 시뮬레이션을 통하여 얻었다. 가스화기 시뮬레이션 결과를 토대로 합성석유 및 합성천연가스 생산을 위한 공정의 물질수지식 및 에너지수지식이 계산되었으며 이로부터 각 공정에서 발생되는 부생성물과 폐기물에 대한 양이 결정되고 이를 처리하는 방안 등도 제시되었다. 실증시설은 20,000배럴/일 규모의 CTL 및 전기 병산 시설이 적합하다. 더 큰 규모 공장은 투자비가 너무 커서 유가 또는 석탄가 변동에 따라 사업의 수익성이 크게 변하여 위험도가 큰 단점이 있기 때문이다. CTL 공장에 전기 병산이 추천되는 이유는 산소생산공장(APU), 압축 등 석탄전환공장에는 자체적인 전기수요가 막대하여 따로 스팀터빈용 발전소를 운영하므로 이를 효율적으로 대체하고자 하기 때문이다. 즉, 석탄가스화에 의해 기름을 최대한 만들고 미반응가스는 가스터빈 및 스팀터빈의 복합발전에 의해 고효율로 전기를 생산하면 최소의 비용으로 최대한 전기를 생산하여 자체소비 전력을 충당하고 남는 전기는 판매하여 수익률을 높일 수 있다.

• Plant Journal
• /
• v.10 no.3
• /
• pp.39-44
• /
• 2014

The gas turbine thermal efficiency has been predicted when the compressor pressure ratio increases from the previously set 13.5. Thermal efficiency has been predicted from 14.2 up to 18.2 at which the turbine work reaches its maximum value on the assumption that isentropic efficiency of the compressor and the turbine are constant using the operating data at the pressure ratio of 13.5. 35.11% of thermal efficiency has been acquired by the performance test when the pressure ratio increased to 16.2 since replacing the compressor low pressure stages. It's been approved that predicting thermal efficiency using the operating data at the pressure ratio of 13.5 is useful within 7.86% of tolerance as the figure measured by the performance test.