• 한국강구조학회 논문집
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• 제14권5호통권60호
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• pp.593-602
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• 2002

콘크리트와 강판, PS강재의 구조적 장점을 극대화하여 낮은 형고로 경간을 장대화할 수 있는 새로운 교량 상부구조형식으로서 강재로 구속된 프리스트레스트 콘크리트 합성거더(Steel-Confined Prestressed Concrete Girder; SCP Girder)를 개발하였다. 개발된 SCP 합성거더의 효과적인 설계 및 제작을 위하여 설계프로그램을 개발하고 제작절차를 확립하였다. 이를 바탕으로 설계된 SCP 합성거더를 실물크기로 제작하여 시공성을 확인하였으며, 재하실험을 통해 설계의 타당성과 구조적 안전성 및 실적용 가능성에 대하여 검증하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.79-81
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• 2005

Bridges constructed recently are preferred to have long spans and simple structure details considering not only the function as bridge but scenic beauty, maintenance, construction term and life cycle cost, etc. Therefore, they require high performance steels like extra-thick plate steels and TMCP steels. A TMCP steel produced by themo-mechanical control process is now spot lighted due to the weldability for less carbon equivalent. It improved at strength and toughness in microstructure. Recently, the SM570-TMC steel which is a high strength TMCP steel whose tensile strength is 600MPa has been developed and applied to steel structures. But, for the application of this steel to steel structures, it is necessary to elucidate not only the material characteristics but also the mechanical characteristic of welded joints. In this study, the characteristics of residual stresses in welded joints of SM570-TMC steel were studied through the three-dimensional thermal elastic-plastic analyses on the basis of mechanical properties at high temperatures obtained from the elevated temperature tensile test.

• 한국재난정보학회 논문집
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• 제13권2호
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• pp.258-266
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• 2017

사장교는 특수목적으로 장 경간을 갖는 교량이다. 긴 경간으로 인하여 차량의 이동하중에 대한 동적응답이 매우 특별하다. 거동역시도 비선형을 갖고 있어 설계에 어려움이 많은 형식이다. 연구에서 다양한 차량하중을 고려하여 사장교의 응답을 구하고 장 경간 교량의 이동하중에 대한 거동을 파악한다. 특히, 한 방향과 양방향에 대한 하중이 속도를 가지고 이동할 때 교량의 부재에 대한 거동은 케이블의 유연성에 기인하는 것으로 나타났다. 차량하중의 영향은 케이블의 진동과 함께 수직변형을 증폭하는 경향을 나타내므로 케이블과 바닥판의 동적거동을 포함한 분석이 보다 효과적임을 알 수 있다.

• 한국수소및신에너지학회논문집
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• 제18권2호
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• pp.151-156
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• 2007

Solar cell and nanofiltration membrane were utilized in a system of enzymatic hydrogen production through light-sensitized photoanode, which resembles photoelectrochemical(PEC) configuration. Solar cell uses no additional light energy to increase energy for electrons to reduce protons and for holes to oxidize water to oxygen, and nanofiltration membrane replaces a salt bridge successfully with increased ion transport capability. With this system configuration, optimized amount of enzyme(10.98 unit), and an anodized tubular $TiO_2$ electrode($5^{\circ}C$/1 hr in 0.5 wt% HF-$650^{\circ}C$/5 hr) hydrogen evolved at a rate of ca. $43\;{\mu}mol/(cm^2{\times}hr)$ in a cathodic compartment and oxygen generated at a rate of ca. $20\;{\mu}mol/(cm^2{\times}hr)$ in an anodic compartment. The stoichiometric evolution of gases indicated that water was splitted in the system.

• 대한의용생체공학회:의공학회지
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• 제25권1호
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• pp.65-70
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• 2004

In this paper, we described 23 cases of animal experiment with our pneumatic ventricular assist device and new durability-improvement method. The blood pump consists of blood housing, and back plate made by the injection molding of isoplast, and the diaphragm fabricated by dipping of polyurethane solution onto the aluminum mold. Its volume was 75 $m\ell$ and in-vitro test showed that maximum output was 4.5 $\ell$/min at the 100 mmHg. The adult female sheep with weight of 50 ＋ 10 kg were employed for tile in-vivo experiments and the mean blood flow was sustained at 3.0 1/min. 4 animals survived more than 15 days and the longest survival time was 28 days. In the prior 10 cases, the major causes of death were the tearing of diaphragm at the diaphragm to blood housing junction. By the new mesh and alumina ball milling methods, the durability was enhanced, and its qualitative and quantitative improvement was proved via the in-vivo and in-vitro methods. Animal experiments demonstrated that all the physiologic parameters a ere maintained within the permissible ranges and no thrombus formation was observed through the visual and blood test. The in-vivo experiments demonstrated our pneumatic ventricular assist device to he one month's bridge to transplantation device.

• 대한의용생체공학회:의공학회지
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• 제14권2호
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• pp.163-167
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• 1993

We developed a ventricular assist device(VAD) to be used as a bridge to heart transplantation or a circulatory assist device for patients with end-stage heart disease or poor myocardial function after cardiac surgery. It is a pneumatic and diaphragm-type VAD and its stroke volume is 90 cc. The upper housing and diaphragm is made of a segmented polyurethane and the lower back plate is made of a polycarbonate. Two Carbomedics$^R$ mechanical valves are used as inlet and outlet valves. It was tested in vitro and the cardiac output of the VAD was 7 L/min at a heart rate of 70 bpm. The line pressure from a pressure transducer inserted in the pneumatic line was recorded and compared with the ideal pressure tracing.

• Steel and Composite Structures
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• 제24권6호
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• pp.679-688
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• 2017

A GFRP-concrete composite bridge deck is presented in this paper. This composite deck is composed of concrete and a GFRP plate and is connected by GFRP perfobond (PBL) shear connectors with penetrating GFRP rebar. There are many outstanding advantages in mechanical behavior, corrosion resistance and durability of this composite deck over conventional reinforced concrete decks. To analyze the shear and flexural performance of this GFRP-concrete composite deck, a static loading experiment was carried out on seven specimens. The failure modes, strain development and ultimate bearing capacity were thoroughly examined. Based on elastic theory and strain-based theory, calculation methods for shear and flexural capacity were put forward and revised. The comparison of tested and theoretical capacity results showed that the proposed methods could effectively predict both the flexural and shear capacity of this composite deck. The ACI 440 methods were relatively conservative in predicting flexural capacity and excessively conservative in predicting shear capacity of this composite deck. The analysis of mechanical behavior and the design method can be used for the design of this composite deck and provides a significant foundation for further research.

• Structural Engineering and Mechanics
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• 제67권2호
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• pp.131-142
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• 2018

The perfobond connector, composed of a steel plate with a number of holes, serves as a certain type of shear connector in steel and concrete composite structures. Depending on limits in hole distances and rib heights, various hole shapes including circular-hole and long-hole are alternatives for perfobond connectors. This study presented the results of tests performed on 72 push-out specimens with perfobond connectors. The purpose was to evaluate the shear strength of perfobond connectors with circular-hole and long-hole. The effects of various parameters were investigated, including the hole diameter, the hole length, the hole height, the concrete strength, the existence, diameter and strength of rebar in the hole, the thickness, height and distance of perfobond ribs, and the thickness of concrete slabs. On the basis of 132 push-out test results in references and in this study, an analytical model was proposed by regression analysis to predict the shear strength of perfobond connectors. The proposed equation agreed reasonably well with the experimental results of perfobond connectors with different hole shapes.

• Smart Structures and Systems
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• 제32권4호
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• pp.195-205
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• 2023

The contact acoustic emission (AE) monitoring system is time-consuming and costly for monitoring concrete structures in large scope, in addition, the great difference in acoustic impedance between air and concrete makes the detection process inconvenient. In this work, we broaden the conventional AE source localization method for concrete to the non-contact (air-coupled) micro-electromechanical system (MEMS) microphones array, which collects the energy-rich leaky Rayleigh waves, instead of the relatively weak P-wave. Finite element method was used for the numerical simulations, it is shown that the propagation velocity of leaky Rayleigh waves traveling along the air-concrete interface agrees with the corresponding theoretical properties of Lamb wave modes in an infinite concrete slab. This structures the basis for implementing a non-contact AE source location approach. Based on the experience gained from numerical studies, experimental studies on the proposed air-coupled AE source location in concrete slabs are carried out. Finally, it is shown that the locating map of AE source can be determined using the proposed system, and the accuracy is sufficient for most field monitoring applications on large plate-like concrete structures, such as tunnel lining and bridge deck.

• Journal of Chest Surgery
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• 제56권6호
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• pp.449-451
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• 2023

We report a case of chest wall resection for painful chest wall nonunion, 5 years after traumatic flail chest and a first attempt at surgical treatment. The decision was made to perform surgery again after 2 years of unsuccessful well-conducted analgesic treatment. During surgery, we found the same sites of pseudarthrosis and decided to perform parietectomy of the fifth, sixth, and seventh ribs. A Gore-Tex patch was used to bridge the gap created by the resection. In immediate postoperative care, the patient's pain was quickly and sufficiently eased by stage 1 and 2 pain killers. The results of bone samples taken from the pseudarthrosis sites all found Propionibacterium acnes. Five months after surgery, the patient had considerable improvement in pain sensations. Computed tomography showed healing of ribs, the plate in place, and no sign of complications.