• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1541-1547
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• 2005

In this paper, Dualband internal antenna for GSM/DSC handset is proposed. The antenna has a size of about $38mm{\times}90mm{\times}1mm$, giving a total mobile phone PCB for support and fold type patch of about $30mm{\times}8mm{\times}3.2mm$. This antenna characteriatic facilitates the fine-tuning of the two operating frequencies of 909MHz and 1762MHz in the dualband design. The measured radiation pattern in the E-plane and H-plane for operating frequencies of 909MHz and 1762MHz is compared and analyzed. The designed and fabricated two band internal antenna for GSM/DSC handset have a gain between 0dBi and 2.0dBi at all bands. Also, the electric firld distribution and directivity on human head caused by portable phone is analyzed. An analysis model is composed of a human head model and the antenna mounted on the same ground plane as portable telephone size.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.37-38
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• 2006

본 연구에서는 압전체의 횡 진동모드를 이용한 압전 초음파 진동자를 설계 분석하였다. 이전의 란쥬반 진동자는 진동을 얻기 위하여, 복수의 원판 또는 사각판 형태의 압전 세라믹을 서로 반대 방향으로 분극하여 마주 보도록 설치한 후 전기적으로 병렬로 연결하고 상단 및 하단에 금속부을 부착하여 전체를 볼트로 조인 복잡한 구조와 큰 출력 파워를 갚는 반면, 본 연구에서는 판상형의 압전소자와 일체형 금속진동체를 이용하여 기계적 출력 파워 조절이 용이한 구조의 압전 진동자를 고안하여, 압전진동자의 횡 진동 모드를 이용함으로써 신뢰성과 정확도가 높고 진동효율이 최대가 되도록 설계하였다. 설계 개발된 압전 진동자는 진동의 크기 조절이 용이하여 일반 진동자 뿐 만 아니라, 외과 및 안과 수술에 있어서 인체조직이나 각막상피의 활성화를 유지한 상태에서 안전하게 절개 및 분리 시술용 진동자로 사용 할 수 있는 이점이있다. 압전 진동자는 유한요소법 시뮬레이션 프로그램 (ATILA 5.2.4)을 이용하여 설계를 하였으며 압전소자의 두께는 각각 0.2 mm, 0.5 mm로 제작하여 시뮬레이션 결과와 제작된 샘플의 특성을 비교하였고, 변위측정은 칼날을 결합 한 상태에서 공진 주파수대역 부근 주파수별로 측정 비교하였다.

• Journal of the Korean Arthroscopy Society
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• v.4 no.1
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• pp.71-75
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• 2000

Purpose : To introduce arthroscopic partial meniscectomy fur bucket handle tear of medial meniscus using posteromedial portal, which is superior to arthroscopic partial meniscectomy using standard anterior portals commonly used. Method : After arthroscopic examination of the knee, we reduce the torn meniscus, advance the arthroscope into posteromedial compartment under arthroscopic visualization, we make posteromedial portal with reexamination of the compartment and perform arthroscopic partial meniscectomy. Conclusion : With the technique of arthroscopic partial meniscectomy using standard anterior portals, accurate partial meniscectomy can not be done because of inadequate visual field, associated meniscal injuries of posterior horn and cartilage lesion of posterior aspect of the medial femoral condyle can be missed, commonly posterior cruciate ligament can be injured and artificial damage to weight bearing surface of medial femoral condyle is possible. An arthroscopic partial meniscectomy using posteromedial portal is an excellent method fur bucket handle tear of medial meniscus.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.11
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• pp.12-17
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• 1999

In this paper, we proposed a novel CB-CPW(Conductor Backed CPW) for suppression of crosstalk caused by PPL(Parallel Plate Line) mode in the millimeter wave frequency. The proposed structure is formed by the GaAs main substrate attached on the Si lossy layer. The PPL mode can be suppressed by the Si lossy layer of conductivity ${\sigma}$, and it reduces the crostalk between the nearby transmission lines. Using 200 um thick Si substrate of ${\sigma}$ = 30S/m, as the lossy layer, the crosstalk can be suppressed below - 40 dB at 60 GHz. The proposed method is costly effective because inexpensive Si wafer is employed to suppress the PPL mode, and it can be used in the various types of millimeter wave applications.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.576-582
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• 2016

To cope with international regulations, such as Energy Efficiency Design Index (EEDI), Ship Energy Efficiency Management Plan (SEEMP) and so forth, and to enforce limitations on $CO_2$ emissions, green-ship technology to lower fuel consumption has been actively researched, and the development of an energy-saving device (ESD) is being pursued. In order to design an ESD for small and medium-sized domestic vessels, an analysis on flow characteristics has been performed in the present study. Through a model test and numerical analyses, the characteristics of flow around the stern bilge and bulb have been compared to improve wake quality and resistance performance. As a result of these comparisons and analyses, a vertical plate has been adopted,, as a new ESD. Design criteria for the proposed ESD are also suggested. By applying this new ESD, it is expected that the total resistance and average nominal wake can be reduced by 3.04 % and 18.8 %, respectively.

• Journal of the Korean Institute of Telematics and Electronics
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• v.13 no.3
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• pp.11-15
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• 1976

한국산 천연수정은 보석장식용으로서는 그 품질이 이미 알려져 있으나 수정진동자로서의 특성에 관해서는 아직 보고된 바가 없다. 본 연구는 특히 경상도일대에서 채굴되고 있는 천연수정을 채집, 선별, 가공하여 그 수정진동자로서의 사용가능성을 실험을 통하여 검토한 것이다. 필자들은 채굴현장 근처에서 채집한 원석을 특별히 고안제작된 검사경을 이용하여 분석선별하였으며 X-ray를 사용하여 AT-cut로 orientation 한후 시판을 절단하였다. 다음 적용하여 전기적, 광학적 쌍수상태를 검토하고 다시 선별하였다 Dimensioning은 5MHz를 목표로 하였는데 연잠제를 사용하여 5MHz의 조도까지 연마하고 전극으로서 표준형의 은막을 부착하여 시판을 완성하였다. 시판을 대한 측정결과는 모든 등가정수가 대표적인 수입수정판의 것과 대등하였으며 특히 Q는 모두 105를 넘었다. 온도특성도 AT-cut의 이론치와 대차가 없었으며 -20℃-+100℃ 범위에서 최대 20PPM 이내의 편차를 보였다. 즉, 한국산 천연수정은 적절히 선별, 가공 한다면 부유한 수정진동자의 원재로서 사용할수 있음이 증명되었다. Samples of domestic natural quartz were collected and screened optically and chemically, and, after weeding out portions unfit for electrical resonator, were cut into AT-cut wafers, which in turn were dimensioned, trimmed and lapped into 5MHz resonator units. The results of measurements obtained from the specimens indicated excellent electrical characteristics of domestic natural quartz with the average Q quotient of 10s or higher. Temperature characteristics also showed typical AT-cut corves with the frequency deviation of 20PPM at maximum throughout the range of -20 to 100℃. The experiment on the initial batch of samples amply indicates the excellent electrical quality of domestic natural quartz as quartz resonator units.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.3
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• pp.261-269
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• 2004

The existing concrete beams can be retrofitted or reinforced by attaching carbon fiber or glass fiber sheet beneath the beams. Although diverse design methods and application techniques of the retrofitting are studied and developed, the testing method of examining retrofitted beams have not been put into practice yet. In this study, a bond delamination has been modeled and studied to provide a basis for the development of actual testing equipments. For this purpose, Gaussian and sinusoidal waves with 3GHz and 5GHz center frequency are used as an incident wave and 1mm and 3mm bond delamination under the reinforcement are modeled. In the modeling, Finite Difference-Time Domain algorithm is used to investigate the behavior of electromagnetic waves in concrete. The results have shown that 5GHz waves are suitable for the detection of delamination.

• Archives of Reconstructive Microsurgery
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• v.4 no.1
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• pp.16-22
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• 1995

We analyzed 11 children who underwent epiphyseal transplantation to the forearm for manage growing deformity ranged from 2 years 6 months to years(average 5 years 10 months) follow-up period. Etiologies of the functional impairment of the eleven were five traumatic, three congenital and three tumorous conditions. Lesions of epiphysis were distal radius in eight patients and distal ulna in three patients. Operation was performed with removal of non-functioning or deformed epiphysis followed by transplantation of free vascularized proximal fibular epiphysis with microvascular anastomesis. Evaluation was performed radiologically and functionally. The 9(81.8%) patients showed growth of transplanted epiphysis by radiological examination during follow up. At the last follow up, average growth rate was 0.86cm per year excepts 2 cases of no growth. Active wrist motion near normal to contralateral joint was achieved in 7 patients. In other 2 patients, active joint motion was improved but weaker than contralateral joint. Complications on donor site were two transient peroneal nerve palsy which have been resolved after 2 and 5 months post operation and one valgus ankle deformity. The ankle deformity was corrected with $Langenski\"{o}ld$ operation of the dital tibiofibular fusion. At recipient site, there was one superficial infection and it was easily controlled by systemic antibiotics. Many subsequent reports have described successful nonvascularized epiphyseal transplante, but overall results have been inconsistent and unsatisfactory. Other experimental and clinical studies in the transfer of vascularized epiphyses has encourage its clinical application. We also could gel successful growth in several cases with free vascularized epiphyseal transplantation.

• Clinics in Shoulder and Elbow
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• v.6 no.1
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• pp.44-49
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• 2003

Purpose: Many different operative technique of mid-shaft clavicle fracture have been reported. The aim of this prospective study was to compare the results of anterior or anterior-inferior plating with superior plating on the acute mid-shaft fracture of clavicle Materials and Methods: From February1997 to February 2002, thirty-eight consecutive open reduction and internal fixation with reconstruction plates were performed in thirty-eight patients. from August 1999, anterior or anterior-inferior plating was mainly used, prospectively. The duration of follow-up averaged 17 months (range,23 to 43 months). The mean age was 38 years old (range,21 to 57 years old) on anterior or anterior-inferior plating group and 35 years old (range,24 to 55 years old) on superior plating group. The physician progress note, VAS patient complement score, Roentgenogram and ASES score was evaluated. Results: Four patients were lost to follow-up. There was no statistical difference on mean radiological bone union time （8.7 weeks vs. 8.6 weeks) and ASES score (92 vs 94) at inferior and superior plating groups (P > 0.05). VAS patient complement score was very good or excellent on anterior or anterior-inferior group, average score was 1.1 (ranger,0 to 2) compare with superior plating group (P < 0.05). There were two cases of infection, 1 case of failed fixation on superior plating group and 1 case of delayed union on anterior inferior plating group. Conclusion: Anterior inferior plating on acute clavicle midshaft fracture results in excellent patient complement score compare with conventional superior reconstruction plate.

• Journal of Korean Society of Steel Construction
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• v.23 no.1
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• pp.125-135
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• 2011

To obtain a lower story height with a long span and better fire resistance, a new composite floor system using GFRP (glass-fiber-reinforced plastics) was proposed. This floor system consists of asymmetric steel with a web opening, a hollow core ball, concrete, and GFRP. To evaluate the flexural performance of the new composite floor system, an experiment was conducted. The test parameters were the presence of GFRP, the void ratio in relation to the hollow core balls, and the web opening. The test results showed that the resistance and stiffness of the specimen with GFRP were 10% higher than those of the reference specimen, and that fully composite action was accomplished up to the yielding point. After the attainment of the yield strength, the ductility of the specimen was reduced due to the stress concentration around the web openings. The slip between the concrete and steel beam, however, was small. Thus, in the design of the proposed new floor systems, it is desirable that the calculated resistance be reduced by 15%, for safety.