• Tribology and Lubricants
• /
• 제13권3호
• /
• pp.93-101
• /
• 1997

The numerical results on the stress distributions of rail-wheel contact problems are presented for three models in a high-speed rail system. These models which have straight and tapered (1:40 and 1:20) contact geometries between the wheelset and rail are analyzed using the finite element approach. From the simulation results we found that the tapered geometry (1:20) of railwheel contact base line showed very stable contact stress distributions for a whole contact position between the wheel and rail in a curved rail section. The FEM computed results may present an optimized slope geometry of rail-wheel contact in a high-speed railway system.

• 한국생활과학회지
• /
• 제8권1호
• /
• pp.165-178
• /
• 1999

Knitwears it was only for the innerwear, but which has become more available for sportswear and highly valuable formal-dresses for women's apparel and is set a trend toward high value-added products worldwide. Also the industry connected knitwears is more widely applicative than woven industry and is running on the well founded basement for the small enterprises. This study notes that what problems are caused and which utilities can be expected when we design knitwears by Primavision and Texpia CAD system considered the programs for development of domestic knitwears industry. There are much various benefits for designing knitwears from CAD system as shortening working hours, convenience, accuracy, quality control and productivity. It doesn't depend on designer's technique, sense and experiences, but provides, through building the design accuracy, chance to have a precise communication with buyers to be satisfied with the multiplicity, uniqueness and high-quality resulting from reducing the mistake on the operation. But there are some problems for using CAD design system those are no selections for the form, type and thickness of the yarn. Even though it is knitted by the same gauge, the texture conditions show complete difference if the form and thickness is different with. The gauge control without regarding those ought to be improved and the yarn designing function should be appended like in a tektite design. And the CAD design system can not reflect the variables of operating knitting machine and needle. The CAD design system provides the manufacturers with merits those they can change the colors easily to select which one appeals to the customer and check the effects of producing and modeling on monitor. But, in the each producing progress, there are still problems to reduce the practical steps, so intensive care is required of each part.

• Structural Engineering and Mechanics
• /
• 제63권6호
• /
• pp.735-742
• /
• 2017

Steel cables as the most important components are widely used in the certain types of structures such as cable-supported bridges, but the long-span structures may result in an increase in fatigue under high stress and corrosion of steel cables. The traditional steel cable is becoming a more evident hindrance. Fiber Reinforced Polymer (FRP) cables with lightweight, high-strength are widely used in civil engineering, but there is little research in vibrational characteristics of FRP cables, especially on the damping characteristic. This article studied the two methods to evaluate dynamical damping characteristic of basalt FRP(BFRP) and glass FRP(GFRP) cables. First, the vibration tests of the B/G FRP cables with different diameter and different cable force were executed. Second, the cables forces were calculated using dynamic strain, static strain and dynamic acceleration respectively, which were further compared with the measured force. Third, experimental modal damping of each cables was calculated by the half power point method, and was compared with the calculation by Rayleigh damping theory and energy dissipation damping theory. The results indicate that (1) The experimental damping of FRP cables decreases with the increase of cable force, and the trend of experimental damping changes is roughly similar with the theoretical damping. (2) The distribution of modal damping calculated by Rayleigh damping theory is closer to the experimental results, and the damping performance of GFRP cables is better than BFRP cables.

• 한국진공학회지
• /
• 제13권2호
• /
• pp.54-58
• /
• 2004

스테인레스 스틸로 가공된 진공용기에 제조회사와 사양이 각각 다른 세 개의 열음극 전리진공게이지를 부착하고 실험실 온도변화에 따른 게이지들의 압력요동 특성을 조사하였다. 상온 근방의 최소 $20 ^{\circ}C$와 최대 $26 ^{\circ}C$에서의 압력 편차는 각각 IG1은 5.0 %, IG2는 5.3 %, 그리고 IG3는 10.3 %이었다. 그러나 온도 $21.5^{\circ}C$에서 $22.5^{\circ}C$구간에서의 압력변화는 모두 게이지들의 불확도 보다 작고 안정한 성능을 보였다. 본 연구결과 상온 고진공에서 열음극 전리진공게이지의 압력변화는 게이지 자체의 특성 때문이 아니고 실험실 온도 때문에 변하는 압력변화에 기인한 것임을 알 수 있었다.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2003년도 추계학술발표회
• /
• pp.219-225
• /
• 2003

The present study intends to assess the long-term steric sea-level change and its prediction, and potential impacts to the sea-level rise due to the 21st global warming in the coastal zone of the Korea in which much socioeconomic activities have been occurred. The analysis of the 23 tide-gauge data near Korea reveals the overall mean sea-level trend of 2.31 mm/yr.In the satellite altimeter data (Topex/Poseidon and ERS), the sea-level trend in the East Sea is 4.6mm/yr. Both are larger than those of the global average value. However, it is quite questionable that the sea-level trends with the tide-gauge data on the neighboring seas of Korea relate to global warming because of the relatively short observation period and large spatial variability. It is also not clear whether the high trend of altimeter data in the East Sea is related to the acceleration of sea level rise in the Sea, short response time of the Sea, natural variability such as decadal variability, short duration of the altimeter. The coastal zone of Korea appears to be quite vulnerable to the 21st sea level rise such that for the I-m sea level rise with high tide and storm surge, the inundation area is 2,643 km2, which is about $1.2\%$ of total area and the population in the risk areas of inundation is 1.255 million, about $2.6\%$ of total population. The coastal zone west of Korea is appeared to be the most vulnerable area compared to the east and south. In the west of the Korea, the North Korea appears to be more vulnerable than South Korea. In order to cope with the future possible impact of sea-level rise to the coastal zone of Korea effectively, it is essential to improve scientific information in the sea-level rise trend, regional prediction, and vulnerability assessment near Korean coast.

• Journal of Mechanical Science and Technology
• /
• 제17권9호
• /
• pp.1349-1357
• /
• 2003

This paper deals with verification of the theoretical model for dynamic behavior of Pipeline Inspection Gauge (PIG) traveling through high pressure natural gas pipeline. The dynamic behavior of the PIG depends on the differential pressure across its body. This differential pressure is generated by injected gas flow behind the tail of the PIG and expelled gas flow in front of its nose. To analyze the dynamic behavior characteristics such as gas flow in pipeline, and the PIG position and velocity, not only the mathematical models are derived, but also the theoretical models must be certified by actual pigging experiment. But there is not any found results of research on the experimental certification for dynamic behavior of the PIG. The reason is why the fabrication of the PIG as well as, a field application are very difficult. In this research, the effectiveness of the introduced solution using the method of characteristics (MOC) was certified through field application. In-line inspection tool, 30" geometry PIG, was fabricated and actual pigging was carried out at the pipeline segment in Korea Gas Corporation (KOGAS) high pressure system, Incheon LT (LNG Terminal) -Namdong GS (Governor Station) line. Pigging is fulfilled successfully. Comparison of simulation results with experimental results show that the derived mathematical models and the proposed computational schemes are effective for predicting the position and velocity of the PIG with a given operational conditions of pipeline.

• 수산해양기술연구
• /
• 제20권1호
• /
• pp.1-5
• /
• 1984

고기가 자망에 이망될 숙건하에 그물면에 작용하는 붕어(Carassius carassius)의 유영력을 시험수조에서 strain gauge를 써서 즉정한 결과는 다음과 같다. 1. 순간최대유영력 및 지속최대유영력과의 체중과의 관계는 F 하(M) =1.45W, F 하(s) =0.29W 이다. 2. 순관최대유영력 및 지속최대유영력과의 체중과의 관계는 F 하(M) =0.11L 상(2.63), F 하(S) =0.15L 상(1.77)이다. 3. 붕어의 유체저항계수는 C 하(s) ≒0.287이다.

• 센서학회지
• /
• 제6권5호
• /
• pp.385-391
• /
• 1997

본 연구의 목적은 성토시공관리응 방사성 동위원소 이용계기의 회로개발에 있다. 본 연구에서 제작한 계기는 국내 원자력법에서 제한하는 세기 이하의 밀봉선원을 사용하며, 감마선과 열중성자 검출회로, 고전압 공급장치 그리고 마이크로프로세서 등으로 구성하였다. 성토의 밀도측정에 충분한 계측수를 얻기 위하여 감마선 검출 5회로, 열중성자 검출 2회로로 구성하였다. 감마선의 검출은 G-M 검출기의 전기적 특성상 검출회로가 간단하므로 파형정형회로만 거쳐 계수된다. 그러나 He-3 검출기에서 발생하는 열중성자 신호펄스는 대단히 작기 때문에 최대 50 [dB]까지 증폭하고 창비교기(window comparator)를 거쳐 원하는 신호만 계수할 수 있도록 하였다. 모든 회로는 자연 방사선과 잡음에 의한 영향을 최소화하기 위하여 정전차폐하였으며, 계수관에 인가하는 고전압의 리플 진폭과 주파수를 고려하여 펄스 계수시에 리플 성분에 의한 펄스수는 제거하였다. 방사선의 계수 및 연산처리에는 원칩 마이크로프로세서를 이용하였으며, 계측결과는 메모리장치에 저장되고 PC와의 통신도 가능하다. 시제작한 RI계기의 검출성능을 평가한 결과 성토의 밀도측정에 충분한 계측수를 얻을 수 있음이 확인되었다.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
• /
• pp.33-36
• /
• 2005

In this research, for the smart health monitoring of the hydrogen storage high pressure composite vessel, the feasibility study of an embedded fiber Bragg grating(FBG) sensor is carried out. To verify strain measurement in various temperature environment which is needed for the hydrogen pressure vessel, tensile test of a composite specimen with both an embedded FBG sensor and a strain gauge is made in low temperature. Before we try a real-size hydrogen storage pressure vessel, a small & cheap composite pressure vessel having the same structure is fabricated with embedded FBG sensors and tested. In the case of an aluminum liner inside the vessel, survivability of FBG sensors at the interface is lower than the other areas.

• 비파괴검사학회지
• /
• 제2권2호
• /
• pp.9-16
• /
• 1983

There are two weak points in a high pressure vessel, one is a corner, the other is a crack on the base. In order to evaluate safety of a department of a corner and a crack like a starfish on the base in a high pressure vessel (working pressure: $130kg/cm^{2}$), which was made by Marison's Process, we analyzed stress by strain gauge, measured thickness and hardness by ultrasonic testing, and were able to test pressure by water pressure from nondestructive testing. Also destructive testings were applied to measure thickness and to observe microstructure and chemical composition of a corner on the base. From the results of the experiment, values of experiment were satisfied with a condition of application. But, it is considered that a crack on the base is to be investigated with more by Fracture Mechanics.