• 구강회복응용과학지
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• 제27권2호
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• pp.223-231
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• 2011

본 증례 보고의 목적은 상악 무치악 환자에서 임플란트 지지 피개의치를 위한 $Locator^{(R)}$ attachment가 장착된 새로운 milled titanium bar를 소개하고 새로운 대안으로써의 가능성을 제시하고자 함이다. 56세 남자 환자가 상악 고정성 보철물(10-유닛 브릿지)의 동요도를 주소로 본원에 내원하였다. 악관절 및 치과 치료에 영향을 줄만한 특이한 전신병력은 없었다. 방사선 검사 및 임상 검사 결과, 상악의 경우 모든 잔존치아에서 심한 골흡수와 동요도를 보이고 있어 전악 발치를 시행한 후, 임플란트 지지 피개의치를 제작하기로 하였다. 의치의 안정성과 유지력, 저작효율, 청소의 용이성, 심미성과 발음 그리고 경제적인 측면을 고려하여 $Locator^{(R)}$ 어태치먼트를 CAD/CAM으로 제작된 milled titanium bar에 탭핑(tapping)으로 연결시키는 새로운 디자인을 고안하였으며, 1년 이상 경과 후, 기능과 심미적인 면에서 만족할 만한 성과를 얻었기에 이를 보고하는 바이다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권1호
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• pp.9-20
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• 2018

Due to integrated stochastic wind and wave loads, the supporting platform of a Floating Offshore Wind Turbine (FOWT) has to bear six Degrees of Freedom (DOF) motion, which makes the random cyclic loads acting on the structural components, for instance the tower base, more complicated than those on bottom-fixed or land-based wind turbines. These cyclic loads may cause unexpected fatigue damages on a FOWT. This paper presents a study on short-term fatigue damage at the tower base of a 5 MW FOWT with a spar-type platform. Fully coupled time-domain simulations code FAST is used and realistic environment conditions are considered to obtain the loads and structural stresses at the tower base. Then the cumulative fatigue damage is calculated based on rainflow counting method and Miner's rule. Moreover, the effects of the simulation length, the wind-wave misalignment, the wind-only condition and the wave-only condition on the fatigue damage are investigated. It is found that the wind and wave induced loads affect the tower base's axial stress separately and in a decoupled way, and the wave-induced fatigue damage is greater than that induced by the wind loads. Under the environment conditions with rated wind speed, the tower base experiences the highest fatigue damage when the joint probability of the wind and wave is included in the calculation. Moreover, it is also found that 1 h simulation length is sufficient to give an appropriate fatigue damage estimated life for FOWT.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권2호
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• pp.88-93
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• 2005

To develop a 100 hp high temperature superconducting(HTS) motor with high efficiency first in Korea, we fabricated a HTS field winding and test. HTS field winding is composed of sixteen HTS race track shaped coils wound with stainless steel-reinforced Bi-2223 tape conductor by react and wind fabrication method. Nomex paper was used for electrical insulation. Each of four magnet pole assemblies was constructed with four double pancake sub-coils, mechanically stacked and electrically in series. Four magnet assemblies were fixed on an aluminum support structure to make effective heat transfer. The Critical current (Ic) was 41.5A at 77K and self field. However the lowest Ic value of sub-coils was 35A. Joule heat generated by each joints between sub-coils was lower than 1mW at 77K and 34A. And Joule heat generated by the joints between field coils was lower than 10mW at 77K and 34A. Joule heat of the whole field winding was 1W at 77K and 32A. And so, the lowest Ic value of sub-coils was more important than Joule heats generated by all joints. The operating current must be lower than the lowest Ic of all the sub-coils. In this paper, design, construction and testing of HTS field winding, Joule heat generated by the joints, and operating current were discussed.

• 한국군사과학기술학회지
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• 제13권3호
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• pp.397-404
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• 2010

Recently, there is on-going research about tactical data link system based on the legacy radio. Tactical data link based on legacy radio is operated mostly in narrow bandwidth under 25khz. Communicating traffics in nodes participated at network need to be minimized for distributing tactical data in narrow bandwidth. In addition, the data distributing structure is necessary for distributing tactical informations such as a situation awareness and so on to war fighters. However, conventional server-client system wastes a lot of time to obtain information for war fighters as user uses pull system to gather necessary information by seeking it one by one. Especially, the fighter pilot is supposed to dedicate into a situation awareness and fight mission in every seconds but seeking information of a user terminal while aircraft maneuvering affects as obstacle to concentrate engaging hostiles. therefore, push technology, the tactical data distributing system, is necessary for war fighters to receive fixed tactical data automatically without putting attention to it. This paper propose the UMPC tactical data link push framework. the UMPC tactical data link is a tactical data link system based on the legacy radio. Proposed push framework is verified by composing experiment environment and testing.

• 한국해양공학회지
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• 제34권6호
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• pp.454-460
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• 2020

In 2019, the Korean government announced the 3rd Basic Plan for Energy, which included expanding the rate of renewable energy generation by 30-40% by 2040. Hence, offshore wind power generation, which is relatively easy to construct in large areas, should be considered. The East Sea coast of Korea is a sea area where the depth reaches 50 m, which is deeper than the west coast, even though it is only 2.5 km away from the coastline. Therefore, for offshore wind power projects on the East Sea coast, a floating offshore wind power should be considered instead of a fixed one. In this study, a response analysis was performed by applying the analytical conditions of IEC61400-3-2 for the design of floating offshore wind power generation systems. In the newly revised IEC61400-3-2 international standard, design load cases to be considered in floating offshore wind power systems are specified. The upper structure applied to the numerical analysis was a 5-MW-class wind generator developed by the National Renewable Energy Laboratory (NREL), and the marine environment conditions required for the analysis were based on the Ulsan Meteorological Buoy data from the Korea Meteorological Administration. The FAST v8 developed by NREL was used in the coupled analysis. From the simulation, the maximum response of the six degrees-of-freedom motion and the maximum load response of the joint part were compared. Additionally, redundancy was verified under abnormal conditions. The results indicate that the platform has a maximum displacement radius of approximately 40 m under an extreme sea state, and when one mooring line is broken, this distance increased to approximately 565 m. In conclusion, redundancy should be verified to determine the design of floating offshore wind farms or the arrangement of mooring systems.

• Structural Engineering and Mechanics
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• 제85권3호
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• pp.337-351
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• 2023

In this paper, the shear behavior of soft filling in rectangular-hollow concrete specimens was simulated using the 2D particle flow code (PFC2D). The laboratory-measured properties were used to calibrate some PFC2D micro-properties for modeling the behavior of geo-materials. The dimensions of prepared and modeled samples were 100 mm×100 mm. Some disc type narrow bands were removed from the central part of the model and different lengths of bridge areas (i.e., the distance between internal tips of two joints) with lengths of 30 mm, 50 mm, and 70 mm were produced. Then, the middle of the rectangular hollow was filled with cement material. Three filling sizes with dimensions of 5 mm×5 mm, 10 mm×5 mm, and 15 mm×5 mm were provided for different modeled samples. The parallel bond model was used to calibrate and re-produce these modeled specimens. Therefore, totally, 9 different types of samples were designed for the shear tests in PFC2D. The shear load was gradually applied to the model under a constant loading condition of 3 MPa (σc/3). The loading was continued till shear failure occur in the modeled concrete specimens. It has been shown that both tensile and shear cracks may occur in the fillings. The shear cracks mainly initiated from the crack (joint) tips and coalesced with another one. The shear displacements and shear strengths were both increased as the filling dimensions increased (for the case of a bridge area with a particular fixed length).

• Advances in aircraft and spacecraft science
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• 제10권6호
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• pp.495-519
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• 2023

The drone serves the customers not served by vans. At the same time, considering the safety, policy and terrain as well as the need to replace the battery, the drone needs to be transported by truck to the identified station along with the parcel. From each such station, the drone serves a subset of customers according to a direct assignment pattern, i.e., every time the drone is launched, it serves one demand node and returns to the station to collect another parcel. Similarly, the truck is used to transport the drone and cargo between stations. This is somewhat different from the research of other scholars. In terms of the joint distribution of the drone and road vehicle, most scholars will choose the combination of two transportation tools, while we use three. The drone and vans are responsible for distribution services, and the trucks are responsible for transporting the goods and drone to the station. The goal is to optimize the total delivery cost which includes the transportation costs for the vans and the delivery cost for the drone. A fixed cost is also considered for each drone parking site corresponding to the cost of positioning the drone and using the drone station. A discrete optimization model is presented for the problem in addition to a two-phase heuristic algorithm. The results of a series of computational tests performed to assess the applicability of the model and the efficiency of the heuristic are reported. The results obtained show that nearly 10% of the cost can be saved by combining the traditional delivery mode with the use of a drone and drone stations.

• Clinics in Shoulder and Elbow
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• 제27권1호
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• pp.18-25
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• 2024

Background: The Discovery Elbow System (DES) utilizes a polyethylene bearing within the ulnar component. An exchange bearing requires preoperative freezing and implantation within 2 minutes of freezer removal to allow insertion. We report our outcomes and experience using this technique. Methods: This was an analysis of a two-surgeon consecutive series of DES bearing exchange. Inclusion criteria included patients in which exchange was attempted with a minimum 1-year follow-up. Clinical and radiographic review was performed 1, 2, 3, 5, 8 and 10 years postoperative. Outcome measures included range of movement, Oxford Elbow Score (OES), Mayo Elbow Performance Score (MEPS), complications and requirement for revision surgery. Results: Eleven DESs in 10 patients were included. Indications were bearing wear encountered during humeral component revision (n=5); bearing failure (n=4); and infection treated with debridement, antibiotics and implant retention (DAIR; n=2). Bearing exchange was conducted on the first attempt in 10 cases. One case required a second attempt. One patient developed infection postoperatively managed with two-stage revision. Mean follow-up of the bearing exchange DES was 3 years. No further surgery was required, with no infection recurrence in DAIR cases. Mean elbow flexion-extension and pronosupination arcs were 107°(±22°) and 140° (±26°). Mean OES was 36/48 (±12) and MEPS was 83/100 (±19). Conclusions: Our results support the use of DES bearing exchange in cases of bearing wear with well-fixed stems or acute infection. This series provides surgeons managing DES arthroplasty with management principles, successful and reproducible surgical techniques and expected clinical outcomes in performing DES polyethylene bearing exchange. Level of evidence: IV.

• Geomechanics and Engineering
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• 제36권3호
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• pp.303-316
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• 2024

Seismic records are composed of mainshock and a series of aftershocks which often result in the incremental damage to underground structures and bring great challenges to the rescue of post-disaster and the repair of post-earthquake. In this paper, the repetition method was used to construct the mainshock-aftershocks sequence which was used as the input ground motion for the analysis of dynamic time history. Based on the Daikai station, the two-dimensional finite element model of soil-station was established to explore the failure process of station under different seismic precautionary intensities, and the concept of incremental damage of station was introduced to quantitatively analyze the damage condition of structure under the action of mainshock and two aftershocks. An arc rubber bearing was proposed for the shock absorption. With the arc rubber bearing, the mode of the traditional column end connection was changed from "fixed connection" to "hinged joint", and the ductility of the structure was significantly improved. The results show that the damage condition of the subway station is closely related to the magnitude of the mainshock. When the magnitude of the mainshock is low, the incremental damage to the structure caused by the subsequent aftershocks is little. When the magnitude of the mainshock is high, the subsequent aftershocks will cause serious incremental damage to the structure, and may even lead to the collapse of the station. The arc rubber bearing can reduce the damage to the station. The results can offer a reference for the seismic design of subway stations under the action of mainshock-aftershocks.

• 대한관절경학회지
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• 제10권2호
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• pp.165-172
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• 2006

목적: 자가 슬괵건을 이용한 관절경하 전방십자인대 재건술시 이식건의 경골측 골 터널내 고정의 유용성을 이차 관절경 검사의 추시 관찰을 통하여 평가 하고자 하였다. 대상 및 방법: 1999년 12월부터 2005년 5월까지 자가 슬괵건을 이용한 전방 십자인대 재건술을 시행한 환자 중 이차 관절경 검사를 시행한 32례를 대상으로 하였다. 경골측의 고정방법에 따라 나사못 실고정만을 시행한 군(제 1군)과 나사못 실고정과 간섭나사를 이용한 경골측 골 터널내 고정을 함께 시행한 군(제 2군)으로 구분하였다. 이차 내시경 추시 관찰시의 평균 나이는 30세였으며 남자가 30례, 여자가 2례였고 전방십자인대 재건술 후 이차 관절경 검사를 시행한 기간은 평균 21.3개월이었다. 결과는 마취하의 KT-1000 관절계와 IKDC 분석 및 경골측 골 터널의 크기와 Telos 스트레스 부하 검사를 방사선학적으로 평가하였으며, 이차 관절경 소견의 평가 또한 시행하였다. 결과: 평가한 IKDC분석 및 Telos스트레스 부하 방사선 검사상의 전이 정도와 KT-1000 관절계상의 전이정도는 제2군에서 우수한 소견을 보였으나, 통계적으로 의미 있는 차이를 보이진 않았다. 관절 내시경상의 이식건의 긴장도, 이식건의 육안 소견, 이식건의 활액막 증식 정도도 제2군에서 우수한 소견을 보였으나, 통계적으로 의미 있는 차이를 보이진 않았다. 전후면 방사선 사진상 경골측의 골터널의 확장은 제1군에서 2.3 mm 및 제2군에서 1.7 mm로 측정되어 통계적으로 의미 있는 차이를 보였다(P=0.042). 결론: 자가 슬괵건을 이용한 십자 인대 재건술에서 경골측 골 터널내 고정의 부가하는 시술은 경골측 골터널의 확대를 의미 있게 감소 시켰으나 수술 후의 임상적 결과, 관절의 동요 정도, 관절경적 소견에 있어 유의한 차이는 보이지 않았다. 본 연구에서 경골측 고정을 위해 나사못 실고정 단독으로 사용하여도 만족스러운 임상적 결과, 관절의 안정도, 이식건의 성숙을 얻을 수 있었고 경골측 골터널의 확대는 결과에 영향을 미치지 않는다는 것을 알 수 있었다.