• Journal of the Korean Chemical Society
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• v.29 no.4
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• pp.335-340
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• 1985

The crystal structure of ethylenediammonium bis (p-methylbenzenesulfonate) monohydrate, $C_2H_{10}N_{22}^{+2}{\cdot}(C_7O_3H_7S^-){\cdot}H_2O$ has been determined by X-ray diffraction techniques. The space group is P21, in 2 unit cell with a = 12.649 (2) ${\AA}$, b = 7.727 (1) ${\AA}$, c = 11.295 (2) ${\AA}$, ${\beta}$ =111.8(1)$^{\circ}$, and z = 2. The structure was solved by direct methods and refined to R = 0.060 for 1134 reflections measured with Mo-K${\alpha}$ radiation. Two p-methylbenzenesulfonates, fragment A and B, from a pair through the hydrogen bonds to the ethylenediammonium ion. The sulfonate group in the fragment B are disordered. There are six unique hydrogen bonds, of which four are between the ethylenediammonium ion and the sulfonate groups and remaining two involve the water molecule.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1212-1223
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• 2006

Microwave(M/W) bands, though having great demand in wireless services, have been used mostly for long distance communications. As a result, the studies on their mobile radio models have been made less than on VHF/UHF. However, as the mobile communication services with M/W bands have been increasing, the development of a more accurate prediction model of the mobile radio environments has been demanded. The development of a reliable radio prediction model in the mobile radio environments requires the measurement and analysis of the characteristics of the radio waves according to reflection, diffraction and scattering of radio signals in various mobile radio environments. The proposed 8 GHz band radio prediction models have 2 different categories: (1) LOS model and (2) non-LOS model. The LOS model predicts signal strength using the analytic result with measured pathless exponents for the waves direct and reflected by ground and buildings, and the non-LOS model suggests a prediction model of received power by calculating the signal variations after diffraction.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.3
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• pp.73-77
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• 2015

This paper presents integrated polymeric spectrometer module which offers compact size, easily-fabricated structure and low cost. The proposed spectrometer module includes the nano diffraction grating with non-uniform pitch and planar optical waveguide with concave mirror to be fabricated by UV imprint lithography. To increase the reflection efficiency, we designed the nano diffraction grating with triangular profiles. The polymeric planar spectrometer includes a spectral bandwidth of 700 nm, resolution of 10 nm and precision below 5 nm. This polymeric planar spectrometer is well-suited for sensor system.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.2
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• pp.22-27
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• 2000

We present a sequential stereoscopic display system using volume holographic storage. Multiple angular multiplexed stereoscopic image pairs are recorded into a photorefractive crystal that can store data with high density, transfer them with high speed, and select a randomly chosen data element. The reference beam with Bragg selectivity is scattered by the index grating and the diffracted beams are propagating along the directions of the stereoscopic image pairs. The images are to be suitably projected on the left and right display plane sequentially for stereoscopic video viewing.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1175-1182
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• 2000

Diffraction systematically causes error in acoustic measurements. Most probes are designed to reduce this phenomenon. On the contrary, this paper proposes a spherical probe a] lowing acoustic inten sity measurements in three dimensions to be made, which creates a diffracted field that is well-defined, thanks to analytic solution of diffraction phenomena. Six microphones are distributed on the surface of the sphere along three rectangular axes. Its measurement technique is not based on finite difference approximation, as is the case for the ID probe but on the analytic solution of diffraction phenomena. In fact, the success of sound source identification depends on the inverse models used to estimate inverse diffraction phenomena, which has nonlinear properties. In this paper, we propose the concept of nonlinear inverse diffraction modeling using a neural network and the idea of 3 dimensional sound source identification with better performances. A number of computer simulations are carried out in order to demonstrate the diffraction phenomena under various angles. Simulations for the inverse modeling of diffraction phenomena have been successfully conducted in showing the superiority of the neural network.

• Korean Journal of Optics and Photonics
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• v.10 no.4
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• pp.348-353
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• 1999

Ray-optics approach based on the rigorous coupled wave theory, called by the rigorous ray-optics method (RROM), is developed for the calculation of couling coefficients of waveguide grating devices. The coupling coefficients of several grating structures, such as rectangular, sinusoidal, triangle, and trapezoidal shapes, are determined by the RROM, and they are compared with those obtained by conventional methods of the ray-optics method (ROM) and the coupled mode method (CMM). In the case of rectangular gratings, the coupling coefficients is evaluated in detail by various depths and duty-cycles of the grating. We have found that the RROM gives more exact solutions for the coupling coefficients of even arbitrary shapes of diffractive waveguide grating devices than the other conventional methods.

• Korean Journal of Optics and Photonics
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• v.10 no.4
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• pp.328-334
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• 1999

Methylene blue-sensitized photopolymerizable material based on acrylamide is investigated with two-wave energy coupling experiments. Differently from other studies, self-diffraction oscillations are observed and the grating phase is determined without applying external electric fields, moving nonlinear materials, and phase shifting one of two writing beams. The phase grating showed a phase shift of $\pm$50$^{\circ}$ with respect to the intensity grating. Modified Kogelnik's coupled wave equation considering the mixed gratings of phase and absorption gratings and nonzero spatial phase shifts of the gratings with respect to the intensity interference patterns formed during the two-wave energy coupling is discussed in detail to understand these phenomenon.

• Journal of Ocean Engineering and Technology
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• v.30 no.3
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• pp.151-160
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• 2016

The diffraction and radiation of linear waves by an array of truncated floating multiple buoys are solved using the interaction theory based on a matched eigenfunction expansion method (MEEM). The interaction processes between multiple buoys are very complex and numerous, because the scattered and radiated waves from each buoy affect the others in the array. Our primary aim is therefore to construct the rigorous wave exciting forces and hydrodynamic forces to deal with the problem of multiple interactions. This present method is applied to a square array of four buoys with two incidence angles, and the results are given for the wave excitation forces on each buoy, heave RAO for each buoy heaving independently, and wave elevations around the buoys and wave run-up. The analytical solutions are in good agreement with the numerical solutions obtained from commercial code (WAMIT).

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.83-84
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• 2013

홀로그래픽 스테레오그램은, 양안 스테레오스코픽 영상들을 레이저 기준파와 간섭시켜 생성된 홀로그래픽 패턴을 감광매질인 홀로그래픽 필름에 기록한 후, 이를 다시 광학적 회절을 이용하여 3차원 영상으로 재현하는 3차원 디스플레이의 한 방법이다. 본 논문에서는 다시점의 full-color, full-parallax 영상을 디지털 방식의 스테레오그램으로 제작하여 3차원 입체 영상으로 재현하기 위한 기록 시스템에서, 기록 매질인 홀로그래픽 필름 면에서의 영상을 고해상도 영상 센서를 이용하여 직접 획득하고, 이 영상 정보를 분석하여 광축을 제어함으로써, 왜곡없는 최적의 호겔을 형성하여 높은 회절 효율을 갖는 스테레오그램을 제작하기 위한 방법 및 장치에 대한 연구개발 결과를 기술하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.157-161
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• 2000

본 논문은 2린 대역의 마이크로 셀 환경에서 원편파 특성을 분석하기 위하여 편파의 특성을 이론적 해석과 실제 측정 데이터를 비교 검토하였다. 가시거리에서는 원편파가 기수회 반사파 수신을 억제하기 때문에 다중경로 페이딩에 대한 경감 효과가 있다는 것은 널리 알려져 있다. 본 연구팀은 "E"자형 건물의 회절 음영 지역에서도 원편파의 편파 특성이 잘 유지되는지를 측정 분석하였다. 이를 위해 정선회 원편파(C), 역선회 원편파(X), 수직편파(V), 수평편파(H) 안테나를 사용하여 각각의 송수신 편파간 조합에 대하여 거리에 따른 전계강도를 이동 측정하였다. 전파 모델은 "E"자형 건물의 회절지역 모델에서 2개의 경로를 선택하여 각각에 대한 전파의 편파 특성을 분석하였다.대한 전파의 편파 특성을 분석하였다.