• 한국소음진동공학회논문집
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• 제11권4호
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• pp.43-51
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• 2001

An experimental modal analysis is the process to identify structure's dynamic characteristics such as resonant frequencies, damping values and mode shapes. An experimental model was made of stainless steel in the shape of a circular cylindrical shell and installed on the test bed with jigs. For investigating vibrational characteristics of the continuous circular cylindrical shell with intermediate supports, modal testing is performed by using impact hammer, accelerometer and 8-channel FFT analyzer. The frequency response function(FRF) measurements are also made on the experimental model within the frequency range from 0 to 4kHz. Modal parameters are identified from resonant peaks in the FRF's and animated deformation patterns associated with each of the resonances are shown on a computer screen. The experimental results are compared with analytical and FEA results.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1691-1696
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• 2010

Jeong-Ji overbridge is designed to be 9.3km long, the longest for a high speed railway bridge ever constructed in Korea. This bridge is constituted of three types of structure. Standard type bridge is 35m PSC Box bridge which will be constructed by Precast Span Method. To cross the Cheonan Nonsan Expressway, 80m three-span steel arch bridge is designed to avoid rail expansion joint. Finally, Extradosed bridge is planned for high speed railway bridge for the first time in Korea based on originative and advanced design techniques. It is expected that this will contribute to the development of national technology for long-span high speed railway bridges.

• 유통과학연구
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• 제12권7호
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• pp.37-44
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• 2014

Purpose - This study reviews changes in the automobile export-import structure between Japan and USA through a trade related index, and focuses on analyzing comparative advantage based on time-series analysis of statistical data (2000, 2005, and 2012) by using the trade intensity index (TII), revealed comparative advantage index (RCA), and trade specialization index (TSI). Research design, data, and methodology - Japan and USA have mutually complementary economic phase characteristics. Therefore, this study aimed to understand each country's trade structure, to strengthen Japan-USA economic cooperation and aimed to examine trade drawbacks to analyze causes affecting trade and ways to improve it to facilitate its expansion. Results - These two economies have immense complementary potential and, further, significantly greater profits are assured from trade between them, as compared to any other integrated regional economic community. Conclusion - Economic cooperation between these two powers can provide opportunities for industry technology cooperation through partnerships against the backdrop of accelerating competition among industries, by identifying opportunities to secure stable resource suppliers and enlarge the export market.

• 무역학회지
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• 제42권6호
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• pp.111-129
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• 2017

세계은행 통계에 따르면 2013~2016년 기간 중 세계 경제 성장에 대한 중국의 기여도는 31.6%인 것으로 나타났다. 이는 미국, EU 및 일본의 기여도를 합한 29.0%에 비해 높은 수치로서 중국 경제가 세계 경제에 미치는 영향력이 상당히 크다고 볼 수 있다. 본 연구는 중국의 주요 품목별(화학제품, 곡물, 철재, 원유, 컨테이너) 연도별 수출입 해상물동량이 세계 경제성장에 미치는 영향을 시계열 데이터 분석 모형을 적용하여 분석하였다. 총 분석기간은 1999~2016년이며, 제1기(1999~2007년)와 제2기(2008~2016년)의 시기별 분석을 수행함으로써 중국 무역이 세계 경제에 미치는 영향력 측면에서 시기별로 어떠한 구조적 변화가 발생했는지 조명하였다. 특히 대다수 선행연구들이 세계 무역이 세계 경제에 미치는 영향력을 분석하였다면, 본 연구는 중국 무역의 영향력을 분석하여 세계 무역 대국으로 부상하고 있는 중국을 집중적으로 분석하였다는 데 의의가 있다.

• 한국구조물진단유지관리공학회 논문집
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• 제26권1호
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• pp.29-38
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• 2022

국내 지진발생의 증가에 따라 구조물 간의 접합 및 비구조물과 구조물의 연결에 사용되는 앵커의 내진설계가 필요하다. 이 논문에서는 지진 발생으로 균열폭이 커지는 경우에도 인장성능을 발현할도록 개발된 내진용 스테인리스스틸 확장식 후설치 앵커의 인장실험을 수행하였다. 현장에서 주로 사용하는 앵커의 지름 중 12 mm와 20 mm 앵커를 사용하였다. 확장식 후설치앵커의 내진성능을 평가하기위해 비균열 콘크리트와 균열 콘크리트에서 실험을 수행하였고 실험 방법은 콘크리트용 앵커 설계법 및 예제집 2판(KCI, 2018)에 따라 수행하였다. 실험변수는 균열의 유무, 콘크리트 압축강도, 앵커의 묻힘깊이 3가지이다. 평가는 콘크리트용 앵커 설계법 및 예제집 2판(KCI, 2018)에 제시된 방법인 유효계수(k_c)값에 5% 분위수 안전율을 적용한 특성강도(K_5%)를 이용하여 평가하였다. 설계기준에서 정의된 콘크리트브레이크아웃파괴를 위한 특성강도(K_5%)는 비균열과 균열콘크리트에서 각각 9.8과 7.0 이다. 실험군에서 설계기준보다 높은 특성강도(K_5%)가 발현되어 이 값을 콘크리트브레이크아웃강도로 사용할 수 있다.

• Steel and Composite Structures
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• 제44권2호
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• pp.271-281
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• 2022

This study discusses challenges of running expandable profile liners (EPLs) to isolate trouble zones in directional section of a deep well, and summary the expandable profile liner technology (EPLT) field trial experience. Technically, the trial result reveals that it is feasible to apply the EPLT solving lost-circulation control problem and wellbore instability in the deep directional section. Propose schemes for optimizing the EPLT operation procedure to break through the existing bottleneck of EPLT in the deep directional section. Better-performing transition joints are developed to improve EPL string reliability in high borehole curvature section. High-performing and reliable expanders reduce the number of trips, offer excellent mechanical shaping efficiency, simplify the EPLT operation procedure. Application of the expansion and repair integrated tool could minimize the risk of insufficient expansion and increase the operational length of the EPL string. The new welding process and integrated automatic welding equipment improve the welding quality and EPL string structural integrity. These optimization schemes and recent new advancements in EPLT can bring significant economic benefits and promote the application of EPLT to meet future challenges.

• 설비공학논문집
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• 제25권11호
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• pp.595-599
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• 2013

The pipes used in buildings are generally categorized into metallic or plastic materials. Metal pipes, such as copper and stainless steel pipes, are mainly used for water and hot water supply, and for the heating system. However, plastic pipes made of polyethylene and cross-linked polyethylene are used for floor heating, water drainage, and air vent systems. Usually, plastic pipes have thermal demerits, such as high linear expansion coefficients and bending phenomenon by hot water, although the pipes have several merits of light weight, low price, low thermal conductivity, and the comparatively high workability of metal pipes. Therefore, if those kind of demerits are overcome, plastic pipes can be easily accepted for hot water systems. This research is aimed to evaluate the applicability for vertical heating pipes of a plastic pipe system consisting of electric fusion fitting of a conductive carbon compound and propylene random glass fiber pipe, through measurement of the expansion rate and leakage in summer and winter seasons, in the apartment construction field.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.571-577
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• 2006

This paper deals with dynamic tensile characteristics for the polypropylene used in an IP(Instrument Panel). The polypropylene is adopted in the dash board of a car, especially PAB(Passenger Air Bag) module. Its dynamic tensile characteristics are important because the PAB module undergoes high speed deformation during the airbag expansion. Since the operating temperature of a car varies from $-40^{\circ}C$ to $90^{\circ}C$ according to the specification, the dynamic tensile tests are performed at a low temperature($-30^{\circ}C$), the room temperature($21^{\circ}C$) and a high temperature($85^{\circ}C$). The tensile tests are carried out at strain rates of six intervals ranged from 0.001/sec to 100/sec in order to obtain the strain rate sensitivity. The flow stress decreases at the high temperature while the strain rate sensitivity increases. Tensile tests of polymers are rather tricky since polymer does not elongate uniformly right after the onset of yielding unlike the conventional steel. A new method is suggested to obtain the stress-strain curve accurately. A true stress-strain curve was estimated from modification of the nominal stress-strain curves obtained from the experiment. The modification was carried out with the help of an optimization scheme accompanied with finite element analysis of the tensile test with a special specimen. The optimization method provided excellent true stress-strain curves by enforcing the load response coincident with the experimental result. The material properties obtained from this paper will be useful to simulate the airbag expansion at the normal and harsh operating conditions.

• Steel and Composite Structures
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• 제46권4호
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• pp.539-551
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• 2023

In order to study the fire resistance of castellated composite beams with ortho-hexagonal holes and different beam-end restraints, temperature rise tests with constant load were conducted on full-scale castellated composite beams with ortho-hexagonal holes and hinge or rigid joint constraints to investigate the temperature distribution, displacement changes and failure patterns of castellated composite beams with two different beam-end constraints during the whole course of fire. The results show that (1) During the fire, the axial pressure and horizontal expansion deformation generated in the rigid joint constrained composite beam were larger than those in the hinge joint constrained castellated composite beam, and their maximum horizontal expansion displacements were 30.2 mm and 17.8 mm, respectively. (2) After the fire, the cracks on the slab surface of the castellated composite beam with rigid joint constraint were more complicated than hinge restraint, and the failure more serious; the lower flange and web at the ends of the castellated steal beams with hinge and rigid joint constraint produced serious local buckling, and the angles of the ortho-hexagonal holes at the support cracked; the welds at both ends of the castellated composite beam with rigid joint constraint cracked. (3) Based on the simplified calculation method of solid-web composite beam, considering the effect of holes on the web, this paper calculated the axial force and displacement of the beam-end constrained castellated composite beams under fire. The calculation results agreed well with the test results.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.580-583
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• 2009

철강 및 제조분야의 생산과 물류의 글로벌화를 위해 생산정보화 시스템에서 접근성 용이와 생산공정 라인의 변화와 시스템 확장에 따른 유지보수 비용의 최소화가 매우 중요하다. 따라서 본 논문에서는 시스템 간의 통합이나 업무 확장에 따른 유지보수 비용을 감소시키고 시스템 사용자의 접근성을 용이하게 하기 위해 객체지향의 디자인 패턴 기법 적용하여 설계하고 JSP를 이용하여 웹 기반 통합설계 관리 시스템을 구현한다. 아울러 제안된 MES 시스템은 세부적으로 설비마스터 코드관리, 설비관리, 점검관리, 수리관리, 고장관리, 통계관리 등의 다양한 기능을 제공하고 있다.