• 한국해양공학회지
• /
• 제22권3호
• /
• pp.89-95
• /
• 2008

Fatigue cracked components often needs to be repaired during service. Standard repair schemes involve strengthening the component by connecting reinforcing members by means of rivets or welding by reducing the crack-tip stress intensity factors. Recent technological advances in fiber reinforced composite materials and adhesive bonding have led to the development of efficient repair schemes. In this study, the influence of various shape parameters on fatigue crack growth in the CCT type uniform thickness plates and the thin-ta-thick type stiffened panels repaired with woven fabric type Kevlar-Epoxy composite patch are studied experimentally.

• ETRI Journal
• /
• 제33권2호
• /
• pp.163-168
• /
• 2011

A Fabry-Perot cavity (FPC) antenna producing both high-gain and circularly-polarized (CP) behavior is proposed. To increase antenna gain and obtain CP characteristics, a superstrate composed of square patches with a pair of truncated corners is placed above the linearly polarized patch antenna with an approximately half-wavelength distance from the ground plane at the operating frequency. The proposed antenna has the advantages of high gain, a simple design, and an excellent boresight axial ratio over the operating frequency bandwidth. Moreover, used in an FPC antenna, the proposed superstrate converts a linear polarization produced by a patch antenna into a circular polarization. In addition, the cavity antenna produces left-hand circular-polarization and right-hand circular-polarization when a patch antenna inside the cavity generates x-direction and y-direction polarization, respectively. The measured and simulated results verify the performance of the antenna.

• Journal of Electrical Engineering and Technology
• /
• 제12권3호
• /
• pp.1250-1256
• /
• 2017

This paper proposes the design of microstrip patch antennas for dual-band polarization adjustment. The antenna has a multi-layer structure for dual-band operation, and each layer contains a resonating patch with surrounding strips separated into two parts. The antenna polarization is adjusted by varying the separated positions of the strips, while fixing other design parameters. To demonstrate the feasibility, an antenna sample with right-hand circular polarization is fabricated, and its antenna characteristics are measured in a full anechoic chamber. The operating principle of polarization adjustment in the dual frequency bands is also verified by observing near electromagnetic fields and the magnetic surface current density around the antenna.

• Journal of Chest Surgery
• /
• 제16권3호
• /
• pp.337-341
• /
• 1983

The experience with operative treatment for total correction of Tetralogy of Fallot at the department of Thoracic and Cardiovascular Surgery, Korea University Hospital from January, 1977, through April, 1983 was reviewed. Of the 29 patients reviewed, male to female occurrence ratio was 22:7 Type of V.S.D. was type II in 26 cases[90%] and total conus defect in 3 cases[10%]. Average size of V.S.D. was 19 mm. Type of Right ventricular outflow tract stenosis was highest frequency with pulmonary valvular and infundibular stenosis combined type in 21 cases[72%], and there were 8 deaths In this group. Type of R.V.O.T. reconstruction contains 2 cases of infundibulectomy only, 1 case of infundibulectomy with valvular commissurotomy, 2 cases of pericardial patch, 23 Cases of pericardial patch with Teflon or Dacron felt reinforced and 1 case of pulmonary valved conduit reconstruction. Operative mortality was higher in outflow patch through pulmonary valve ring. Overall mortality was 31%. Major causes of death and postoperative complications were low output syndrome, complete A-V block acute renal failure, ventricular fibrillation, bleeding brain abscess, and sudden cardiac arrest.

• 한국재료학회지
• /
• 제33권11호
• /
• pp.458-464
• /
• 2023

In order to develop catechin patches for skin regeneration at wound sites, patches with varying concentrations of catechin and chitosan were manufactured. An optimal composition ratio was determined by adjusting the drug release rate and amount, to maximize efficiency. The catechin used in this study was extracted from green tea leaves using a solvent/ultrasonication method, and its characteristics were confirmed through Fourier transform-infrared spectroscopy (FT-IR) and high-performance liquid chromatography (HPLC) analyses. Patches were prepared with different concentrations of catechin and chitosan, and various properties were analyzed using techniques such as FT-IR, water contact angle analysis, and UV-Vis spectroscopy. It was observed that as the chitosan concentration increased, the release of catechin slowed down or almost ceased. A patch manufactured with 1.5 mg/cm² of catechin at a 1 % chitosan concentration exhibited a high initial release rate over 24 h and demonstrated cellular biocompatibility. Consequently, these patches, with tailored release characteristics based on the concentrations of chitosan and catechin, hold promise for use as drug delivery systems in wound healing applications.

• 한국전자파학회논문지
• /
• 제12권2호
• /
• pp.217-226
• /
• 2001

GPS/GLONASS 통합 수신기에서 사용 할 수 있도록 광대역 원편파 특성을 나타내면, 개인 휴대 및 차량용으로도 사용하기 적합한 작은 크기의 세라믹 유전체 패치 안테나를 설계, 제작하였다. 소형화를 위하여 높은 비유전율을 갖는 세라믹 유전체를 이용하였으며, 90。 위상차의 이중 급전 구조를 사용하여 광대역 특성을 구현하고, 또한 원하는 대역에서 낮은 축비를 구현하였다. 제작된 안테나는 -15 dB 대역폭 242 MHz, 축비 3 dB 이하 112。이상의 넓은 반전력 빔폭을 나타내면, GPS 및 GLONASS 신호를 동시에 수신하기 위한 안테나의 특성을 만족하였다.

• 한국정보통신학회논문지
• /
• 제6권3호
• /
• pp.440-444
• /
• 2002

Sierpinski 프랙탈 삼각형을 이용한 원형 편파를 가지는 마이크로스트립 패치 안테나를 제안한다. Sierpinski 프랙탈 삼각형은 3개의 정삼각형을 가지는 구조로 이를 이용하여 sequential 회전 기법에 의해 광대역의 원형 편파를 발생시킬 수 있다. Sierpinski 구조의 1x3 안테나 배열에 대해포트간 분리도(isolation)와 AR(Axial Ratio)의 특성을 살펴보았다.

• Journal of Chest Surgery
• /
• 제20권4호
• /
• pp.780-785
• /
• 1987

Pulmonary atresia with VSD is uncommon congenital anomaly with high mortality in neonatal period. Recently we experienced surgical correction of 2 cases of pulmonary atresia with VSD. The first case was 7-year old female patient and diagnosed as pulmonary atresia with VSD combined PDA. So, total correction was undertaken which consisted of PDA ligation, patch repair of VSD, transannular enlargement of RVOT with woven Dacron vascular graft, and closure of PFO. Postoperative systemic Rt. ventricular and radial artery pressure ratio was 0.44 and her postoperative course was uneventful. The second case was 6-year old male patient diagnosed as pulmonary atresia with VSD and large systemic-pulmonary collateral arteries. There were two large systemic-pulmonary collaterals, one was simply controlled by ligation, but the other was considered to supply Rt. upper lung. So end to side anastomosis was performed to the RVOT patch. Postoperative systolic Rt. ventricular and radial artery pressure ratio was 0.54. During the follow up period he showed clinical picture of Rt. heart failure, which is relatively well controlled with anticongestive therapy.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2002년도 춘계종합학술대회
• /
• pp.234-237
• /
• 2002

Sierpinski 프랙탈 삼각형을 이용한 원형 편파를 가지는 마이크로스트립 패치 안테나를 제안한다. Sierpinski 프랙탈 삼각형은 3개의 정삼각형을 가지는 구조로 이를 이용하여 sequential 회전에 의해 원형 편파를 발생시킬 수 있다. Sierpinski 구조의 $1\times3$ 안테나 배열에 대해 포트간 분리도(isolation) 와 AR(Axial Ratio)의 특성을 살펴보았다.

• Journal of information and communication convergence engineering
• /
• 제16권4호
• /
• pp.203-212
• /
• 2018

In this article, a novel design of patch antenna with wide band characteristics is presented. The proposed antenna is having electrical dimensions of $0.14{\lambda}{\times}0.11{\lambda}$ (at lower initial frequency) and footprints of $150mm^2$. Structural parameters optimization shows 3.1-23.5 GHz frequency range for a (reflection coefficient) $S_{11}{\leq}-10dB$ and simulated gain 6.8 dB is obtained. An equivalent circuit model is proposed to get an insight view of antenna. Advanced Systems Design (ADS) simulation results are obtain which confirm the validity of proposed model. Degenerated foster canonical form has been used to explain the reactance and capacitive behavior idea of simulated proposed antenna's input impedance later on an equivalent circuit model and smith chart is also suggested. HFSS and CST have been used to analyze antenna behavior. The proposed antenna can be further used for microwave image detection applications.