• Proceedings of the Korean Magnestics Society Conference
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• 2005.12a
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• pp.98-99
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• 2005

• The Journal of the Acoustical Society of Korea
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• v.38 no.2
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• pp.231-239
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• 2019

In sonar systems, the passive ranging of a target is an active research area. This paper analyzed the performance of passive ranging based on an array invariant method for different environmental and sonar parameters. The array invariant developed for source range estimation in shallow water. The advantages of this method are that detailed environmental information is not required, and the real-time ranging is possible since the computational burden is very small. Simulation was performed to verify the algorithm. And this method is applied to sea-going experimental data in 2013 near Jinhae port. This study shows the performance of ranging for source orientation, transmission signal length, and length of a receiver through numerical simulation experiments. Also, the results using nested array and uniform line arrays are compared.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.73-73
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• 2010

본 연구에서는 성장된 p-형의 단일벽 탄소 나노튜브 (SWCNT)와 폴리머 코팅으로 n-형 특성을 보이는 SWCNT의 접합으로 pn-접합 소자 어레이를 만들고 특성을 분석한 결과에 대해 발표하고자 한다. Y-cut quartz 기판에 0.1 nm 두께의 철 촉매 패턴을 만들고 화학기상증착법으로 잘 정렬된 SWCNT를 성장시킨 후, 열 박리 테이프 (thermal tape)을 이용하여 정렬된 나노선을 실리콘 옥사이드 기판에 전이한다. 전기적(electrical breakdown)으로 금속성의 나노선을 제거하고 p-형의 나노선 배열을 얻을 수 있다. 이 나노선에 국소적으로 폴리머 (polyethyleneimine: PEI) 코팅을 하여 n-형 특성을 갖는 나노선 패턴을 만들 수 있다. 이를 이용하여 만든 소자는 p-형과 n-형이 하나의 나노선 안에 부분적으로 존재하므로 연결부위의 접촉에 관한 문제가 전혀 없으며 소자를 만들기도 유용하다. 이렇게 준비된 p-형 나노선과 n-형 나노선의 접합에서 정류특성을 관찰하였다. 이러한 passive matrix 소자는 터치패드나 유기발광다이오드와 같은 다양한 소자에 응용 가능하다.

• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.308-316
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• 2013

A set of experiments (Shallow Water 2006, SW06) was carried out in shallow water near the New Jersey shelf break in summer 2006. Significant fluctuations in direct and surface reflected arrivals were observed from the chirp data (1100~2900 Hz) measured on a vertical line array. This paper presents a geoacoustic inverssion technique for short-range acoustic data with fluctuating arrivals and inversion results of experimental data. In order to reduce effects of random sea surface on the inversion, the acoustic energy back-propagated from the array to the source through direct and bottom-reflected paths is defined as the objective function. A multi-step inversion scheme is applied to the data using VFSR (Very Fast Simulated Reannealing) optimization technique. The inversion results show a source depth oscillation period equal to the measured ocean surface wave period. The inverted bottom sound speed is 1645 m/s and is similar to that estimated by other work at the same site.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1223-1232
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• 2008

In this paper, an analytic method is proposed to extract the reference slot admittance required for the design of a non-resonant waveguide edge slot array. A slot and two neighboring transmission line sections of the numerous alternately inclined slots with the identical inclination angle are modelled as a uniform lossy transmission line, and thus, the total ABCD matrix is easily calculated and compared with the simulated or measured one. From this procedure, the complex characteristic impedance and the complex propagation constant of the lossy transmission line are calculated and the normalized slot admittance is analytically obtained. In order to validate the proposed method, the admittance value of a reference slotted waveguide fabricated for designing the X-band edge slot array is extracted and it is compared with the one obtained by the other conventional method.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1033-1038
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• 2022

In this paper, the design of a printed dipole antenna fed by broadside coupled striplines (BCS) for the 3.5GHz band is described. The two fins of the bow tie are, respectively, on the two sides of the substrate. The feeding balanced lines adopted for 1×2 array are the BCS. The obtained numerical results are in good agreement with experimental data. Through experiments with printed dipole antennas of various extended angles, the printed dipole antenna exhibits the wide bandwidth in the desired frequency band, which has a bandwidth of 28% for VSWR < 2.0 : 1. And within this bandwidth, This printed dipole antenna achieves a stable radiation pattern. It is found that the narrow band and feeding for array characteristic which is a disadvantage of the conventional printed dipole antenna can be improved. The radiation pattern showed omnidirectional characteristics and the maximum gain was about 4.4dBi.

• Journal of the Mineralogical Society of Korea
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• v.17 no.4
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• pp.327-338
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• 2004

XRD studies on annealed Na-feldspar (Amelia albite) at $1100^{\circ}C$ showed rapid structural changes due to Si-Al disordering, which resulted in phase transformations from low albite to high albite by 4-days annealing test. TEM SAED analyses on the annealed samples revealed a trend of structural changes, but estimation of the structural state was difficult due to a large deviation of the SAED data. Optimum conditions of CBED analyses on albite was established by employing a cooling specimen holder, 120 kV of acceleration voltage, 37 Jim of condenser aperture size and 25 nm of spot size. A proper orientation showing distinct changes of HOLZ lines corresponding to the structure changes of albite turned out to be close to the [418] direction with $-1.2^{\circ}$ tilting, where the width of two HOLZ lines in low albite was opposite to those in high albite.

• Journal of radiological science and technology
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• v.29 no.4
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• pp.225-228
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• 2006

Purpose: Accurate clinical evaluation of the alignment of the calcaneus relative to the tibia in the coronal plane is essential in the evaluation and treatment of hindfoot pathologic condition. Previously described standard anteroposterior, lateral, and oblique radiographic methods of the foot or ankle do not demonstrate alignment of the tibia relation to the calcaneus in the coronal plane. The purpose of this study was to introduce hindfoot coronal alignment view. Material : 1) Both feet were imaged simultaneously on an elevated, radiolucent foot stand equipment. 2) Both feet stood on a radiolucent platform with equal weight on both feet. 3) Both feet are located foot axis longitudinal perpendicular to the platform. 4) Silhouette tracing around both feet are made, and line is then drawn to bisect the silhouette of the second toe and the outline of the heel. 5) The x-ray beam is angled down approximately $15^{\circ} to $20^{\circ} Result : 1) This image described tibial axis and medial, lateral tuberosity of calcaneus. 2) Calcaneus do not rotated. 3) The view is showed by talotibial joint space. Conclusion: Although computed tomographic and magnetic resonance imaging techniques are capable of demonstrating coronal hindfoot alignment, they lack usefulness in most clinical situations because the foot is imaged in a non-weight bearing position. But hindfoot coronal alignment view is obtained for evaluating position changing of inversion, eversion of the hindfoot and varus, valgus deformity of calcaneus.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.2
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• pp.364-372
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• 1994

Theoretical method for analyzing the radiation pattern of cross-type 5-patch rectangular microstrip antenna is presented. The equivalent circuit of the array antenna is represented by the conventional transmission line model and the radiation admittance derived from the equivalent circuit of the slitted parallel-plate waveguide filled with a dielectric. The calculated results for the radiation pattern are compared with the measured values.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1041-1046
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• 2004

Orthogonal frequency division multiplexing(OFDM) is becoming the chosen modulation technique for wire and wireless communications with fast data rate because of good spectral efficiency and sufficient robustness of fading channel. Digital Video Broadcating is using OFDM to modulate. But Digital Video Broadcating has performance degradation in moving reception according to DOA(Direction of Arrival). The purpose of this paper is to improve reception performance using array antenna in environment with doppler effect.