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능동적 객체간 의미 제약성을 제공하는 자바 기반 객체 - 관계 랩퍼의 구현
김규백(Gyubaek Kim),김홍기(Hongki Kim),현순주(SoonJoo Hyun) 한국정보과학회 1999 한국정보과학회 학술발표논문집 Vol.26 No.2Ⅰ
복잡해지고 있는 응용 프로그램의 스키마를 객체형 모델링 기법을 통해 효과적으로 정의함으로써 풍부한 의미관계를 유지하면서, 보편적인 하부 저장시스템 솔루션으로 제공되는 관계형 DBMS를 활용할 수 있는 객체-관계 접근 방법은 현실적인 선택으로 각광을 받고 있다. 이러한 접근 방법은 객체-관계 랩퍼(Object-Relational Wrapper)의 사용을 통해 가능할 수 있다. 본 논문에서는 기존의 객체-관계 랩퍼들의 문제점들을 지적하면서 보다 능동적으로 객체간의 의미 관계를 유지시켜 주는 새로운 객체-관계 랩퍼의 설계와 구현에 대해 설명한다. 자바로 개발된 객체-관계 랩퍼는 DBMS와 플랫폼에 독립적인 시스템으로 제공되며, 객체간 상속의 무결성 제약 조건을 유지하기 위해 메터 정보를 활용하는 특성을 가지고 있다.
고강도강 용접부의 소성변형 정도에 따른 파괴안전성 평가
안규백(Gyubaek An),박정웅(Jeongung Park),Mituru Ohata,Fumiyoshi Minami 대한용접·접합학회 2019 대한용접·접합학회지 Vol.37 No.6
Fracture toughness of plastic strain (pre-strain) effect was determined as a function of the temperature in structural steels of the 600 to 780 MPa class. Cyclic loading during earthquakes produces plastic strain in the component, which is enhanced at the region of strain concentration. When the great earthquake occur, the steel structure 10-15% strain deformation was recorded at the beam-to-column connection. The steel structure fracture was more likely to occur. Therefore evaluate of plastic stain effect in steel structure to avoid unstable fracture especially in the weld joint (heat-affected zone; HAZ). The critical fracture toughness value (crack tip opening displacement, CTOD) in a large structure with plastic strain, which was applied to the HAZ region, was estimated from a small-scale plastic stained three-point bend specimen. The critical fracture toughness value is a very useful parameter to evaluate the safety of huge structural to avoid unstable fracture. In this study, it was proposed to critical fracture toughness value (CTOD) to avoid unstable fracture with each plastic strain effect.
Off-road 차량용 디젤엔진의 배기가스 저감에 관한 연구
조규백(Gyubaek Cho),김홍석(Hongsuk Kim),강정호(Jeongho Kang) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
To meet the Tier 4 interim regulation, PM and NOx emission are must be reduced 95% and 30% compare to current regulation, respectively. DOC, Partial DPF and DPF systems could be applied on the off road vehicle diesel engine for reduction of PM. EGR, SCR and LNT are also used to reduce NOx emission. In this research, DPF system and HPL EGR system were investigated to decrease PM and NOx emission on the 56kW off road vehicle. As the results of experiments, DOC and DPF system was very useful to remove PM on engine and had high reduction efficiency. Back pressure was acceptable and the rate of power loss also lower than 5%. In the case of applying HPL EGR system on diesel engine, the NOx reduction was effective in low or middle load due to the high differential pressure between turbocharger inlet and intake manifold. NOx emission decrease according to increasing EGR rate, but THC shows the increasing tendency because of the increased fuel consumption to compensate for the power loss by EGR and DPF.
안규백(Gyubaek An),한일욱(Illwook Han),박정웅(Jeongung Park),우완측(Wan Chuck Woo) 대한용접·접합학회 2017 대한용접·접합학회지 Vol.35 No.6
As the recession in shipbuilding industry became longer, domestic shipbuilders focused on the need for high value added and high technology, and strived to build safer vessels. There are LNG carriers and container ships that require representative technologies. Both ship types are rapidly increasing ship size in the 2000s. Recently, there have been the increase of ship size and the development of oil and gas in arctic region. These trends have led to the requirements such as high strength, good toughness at low temperature and good weldability for prevent of brittle fracture at service temperature. Studies on unstable fracture have mainly been conducted to evaluate the brittle crack stopping properties of the high strength steel welded joints through large scale fracture tests, and studies on the difficulty of stopping brittle cracks in welded joints. It is known that BCA (Brittle Crack Arrest) steel has recently been developed to prevent unstable fracture if cracks propagate toward the BCA steel even if brittle cracks occur. Therefore, it is considered that the ship can be dried more easily if a technology capable of inducing the brittle crack to the BCA steel is developed. In this study, we describe a technique for securing unsafe fracture safety by inducing cracks toward the BCA steel, which has excellent brittle crack stopping ability, regardless of the welding process when brittle cracks occur in the superstructure of super large container ships.
안규백(Gyubaek An),홍승래(Seunglae Hong),박정웅(Jeongung Park),노찬승(Chanseung Ro),한일욱(Ilwook Han) 대한용접·접합학회 2017 대한용접·접합학회지 Vol.35 No.3
Recent trends in shipbuilding and offshore industries are a huge increase in the ship size and the exploration and production of oil and natural gas in the arctic offshore region. High performance steel plates are required by these industrial trends. Also in IMO(International Maritime Organization) has begun to regulate of fuel of ship to environmental protection, therefore it is little bit difficult to use bunker-C oil to working ship. As the problem of environmental change such as global warming is emerged, the operation of the ship is considered to be involved in the environmental change problem, and the regulation of environmental pollution is gradually strengthened. As these environmental regulations are strengthened demand for LNG fuel ships is rapidly increasing. Currently, cryogenic steels used in LNG tanks include aluminum alloy, SUS 304, and 9%-Ni steel. Those steels are has high cost to construction of large LNG carrier. The new materials were suggested several steel mills to decrease construction cost and easy construction. The new cryogenic steel should be evaluate safety to applied real structure include LNG ship. Therefore, in this study, fracture toughness of weld joints were investigated with cryogenic steel for application of LNG tank.