• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.4
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• pp.334-344
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• 2009

In the present paper, analytic solutions are derived for scattering of obliquely incident waves by a semi-infinite breakwater or a breakwater gap of partial reflection. In order to examine the appropriateness of the derived solutions, they are compared with the solutions derived by McIver in 1999 and Bowen and McIver in 2002 for a semi-infinite breakwater and a breakwater gap, respectively, in the case of perfect reflection. The derived analytic solutions are used to investigate the effect of reflection coefficient of the breakwater and wave incident angle upon the tranquility at harbor entrance. The tranquility is deteriorated by the reflected waves as the reflection coefficient increases and as the waves are incident more obliquely.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2710-2723
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• 1996

2-dimensional scattering problem of electromagnetic waves by a periodic strip grating on a grounded dielectric slab in case of oblique incidence and arbitrary polarization is analyed by the vector Floquet modal expansion method. Solution convergence versus number of Chebyshev polynomial terms representing the unknown strip current density and number of space harmonics is examined, and some numerical results such as variation of power of significant space harmonics(scattered mode) are compared with those obtained by previous method. In particaluar, the relationship between Bragg blazing phonmena and characteristics mode(current) on the srip is discussed in detail.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.5
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• pp.450-456
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• 2006

In this paper, we report the changes of morphology, transmittance and photoluminescence (PL) in hydrogenated amorphous $As_{40}Ge_{10}Se_{15}S_{35}$ thin films, thermally deposited at the vapor incidence angles (${\theta}$) of $0^{\circ},\;45^{\circ}\;and\;80^{\circ}$. The hydrogenation was carried out under the condition of a $H_2$ pressure ($P_H$) of 20 atm and an annealing temperature range, $T_{Anneal}$ of $150^{\circ}C{\sim}210^{\circ}C$. A columnar structures with an inclination angle of approximately $65{\sim}70^{\circ}$ was formed in $80^{\circ}$-deposited films and then the columnar was broken after hydrogenation. Transmittance increases with an increase of deposition angle and by the hydrogenation. In particular, a broad PL band on the extended region is observed in obliquely deposited films and it increases during the hydrogenation.

• Earthquakes and Structures
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• v.13 no.6
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• pp.573-588
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• 2017

The earthquake input is required when the soil-structure interaction (SSI) analysis is performed by the direct finite element method. In this paper, the earthquake is considered as the obliquely incident plane body wave arising from the truncated linearly elastic layered half space. An earthquake input method is developed for the time-domain three-dimensional SSI analysis. It consists of a new site response analysis method for free field and the viscous-spring artificial boundary condition for scattered field. The proposed earthquake input method can be implemented in the process of building finite element model of commercial software. It can result in the highly accurate solution by using a relatively small SSI model. The initial condition is considered for the nonlinear SSI analysis. The Daikai subway station is analyzed as an example. The effectiveness of the proposed earthquake input method is verified. The effect of the obliquely incident earthquake is studied.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.176-177
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• 2013

Surface plasmon polaritons (SPPs) have attracted the attention of scientists and engineers involved in a wide area of research, microscopy, diagnostics and sensing. SPPs are waves that propagate along the surface of a conductor, usually metals. These are essentially light waves that are trapped on the surface because of their interaction with the free electrons of conductor. In this interaction, the free electrons respond collectively by oscillating in resonance with the light wave. The resonant interaction between the surface charge oscillation and the electromagnetic field of the light constitutes the SPPs and gives rise to its unique properties. In this papers, we studied theoretical and experimental extraordinary transmittance (T) and reflectance (R) of 2 dimensional metal hole array (2D-MHA) on GaAs in consideration of the diffraction orders. The 2d-MHAs was fabricated using ultra-violet photolithography, electron-beam evaporation and standard lift-off process with pitches ranging from 1.8 to $3.2{\mu}m$ and diameter of half of pitch, and was deposited 5-nm thick layer of titanium (Ti) as an adhesion layer and 50-nm thick layer of gold (Au) on the semiinsulating GaAs substrate. We employed both the commercial software (CST Microwave Studio: Computer Simulation Technology GmbH, Darmstadt, Germany) based on a finite integration technique (FIT) and a rigorous coupled wave analysis (RCWA) to calculate transmittance and reflectance. The transmittance was measured at a normal incident, and the reflectance was measured at variable incident angle of range between $30^{\circ}{\sim}80^{\circ}$ with a Nicolet Fourier transmission infrared (FTIR) spectrometer with a KBr beam splitter and a MCT detector. For MHAs of pitch (P), the peaks ${\lambda}$ max in the normal incidence transmittance spectra can be indentified approximately from SP dispersion relation, that is frequency-dependent SP wave vector (ksp). Shown in Fig. 1 is the transmission of P=2.2 um sample at normal incidence. We attribute the observation to be a result of FTIR system may be able to collect the transmitted light with higher diffraction order than 0th order. This is confirmed by calculations: for the MHAs, diffraction efficiency in (0, 0) diffracted orders is lower than in the (${\pm}x$, ${\pm}y$) diffracted orders. To further investigate the result, we calculated the angular dependent transmission of P=2.2 um sample (Fig. 2). The incident angle varies from 30o to 70o with a 10o increment. We also found the splitting character on reflectance measurement. The splitting effect is considered a results of SPPs assisted diffraction process by oblique incidence.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.296-296
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• 2014

We investigate experimentally and theoretically the splitting of surface plasmon (SP) resonance peaks under TE- and TM-polarized illumination. The SP structure at infrared wavelength is fabricated with a 2-dimensional square periodic array of circular holes penetrating through Au (gold) film. In brief, the processing steps to fabricate the SP structure are as follows. (i) A standard optical lithography was performed to produce to a periodic array of photoresist (PR) circular cylinders. (ii) After the PR pattern, e-beam evaporation was used to deposit a 50-nm thick layer of Au. (iii) A lift-off processing with acetone to remove the PR layer, leading to final structure (pitch, $p=2.2{\mu}m$; aperture size, $d=1.1{\mu}m$) as shown in Fig. 1(a). The transmission is measured using a Nicolet Fourier-transform infrared spectroscopy (FTIR) at the incident angle from $0^{\circ}$ to $36^{\circ}$ with a step of $4^{\circ}$ both in TE and TM polarization. Measured first and second order SP resonances at interface between Au and GaAs exhibit the splitting into two branches under TM-polarized light as shown in Fig. 1(b). However, as the incidence angle under TE polarization is increased, the $1^{st}$ order SP resonance peak blue-shifts slightly while the splitting of $2^{nd}$ order SP resonance peak tends to be larger (not shown here). For the purpose of understanding our experimental results qualitatively, SP resonance peak wavelengths can be calculated from momentum matching condition (black circle depicted in Fig. 2(b)), $k_{sp}=k_{\parallel}{\pm}iG_x{\pm}jG_y$, where $k_{sp}$ is the SP wavevector, $k_{\parallel}$ is the in-plane component of incident light wavevector, i and j are SP coupling order, and G is the grating momentum wavevector. Moreover, for better understanding we performed 3D full field electromagnetic simulations of SP structure using a finite integration technique (CST Microwave Studio). Fig. 1(b) shows an excellent agreement between the experimental, calculated and CST-simulated splitting of SP resonance peaks with various incidence angles under TM-polarized illumination (TE results are not shown here). The simulated z-component electric field (Ez) distribution at incident angle, $4^{\circ}$ and $16^{\circ}$ under TM polarization and at the corresponding SP resonance wavelength is shown in Fig. 1(c). The analysis and comparison of theoretical results with experiment indicates a good agreement of the splitting behavior of the surface plasmon resonance modes at oblique incidence both in TE and TM polarization.

• Journal of Korean Foot and Ankle Society
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• v.1 no.1
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• pp.43-50
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• 1997

The tarsometatarsal joint complex is formed by articulation of the five metatarsal bases with the three cuneiform bones and the cuboid bone. Fracture-dislocation of tarsometatarsal area are difficult to recognize on standard radiographs. The exact diagnosis is occasionally delayed. As a result, improper treatment and late sequelae remains. We decided to make a study of patients with normal foot radiographs on 200 cases. Standard radiographic evaluation was used to study the normal variants of the foot and to evaluate the coincided alignment of the lisfranc joint. Accurate accessment on AP & lateral & $30^{\circ}$ oblique projection of radiographs are very adventageous & important, and next final outcome was detected. : 1. Coincided alignment below 1mm and unfolded lisfranc joint on AP projection was well visalized on 1st cuneiform-metatarsal lateral border and 2nd cuneiform-metatarsal medial border. 2. Coincided alignment below 1mm and unfolded lisfranc joint on oblique projection was well visualized on 2nd cuneiform-metatarsal lateral border and 3rd cuneiform-metatarsal medial border and 3rd cuneform-metatarsal lateral border. 3. More proximal location of 2nd lisfranc joint compared to another joint was 196 cases (98%). It is due to inceleration of 2nd metatarsal base between 3rd & 1st cuneiform. 4. 3rd lisfranc joint was volarward position compared to 2nd listranc on lateral projection at 191 cases (95.5%). It's due to anterior covexity of lisfranc joint. 5. Wide dorsal sided 2nd lisfranc is investigated at 189 cases (94.5%). Because of it. 2nd & 3rd lisfrances are mainly volar dislocated usually. 6. Notching on 5th metatarsal base is visible on 171 cases (85.5%). 7. 4th lisfranc joint had offset normally within $2\sim3mm$ at 98 cases (49%). 8. 5th Lisfranc joint had normally offset within $2\sim3mm$ at 99 cases (49.5%). 9. On lateral projection, slight dorsal location of cuneiform to metatarsal base is investigated at 82 cases (41%).

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.354-361
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• 2004

This Paper describes a crack scattering model for SH wave based on the boundary integral equation(BIE) method, where the fundamental unknown is crack opening displacement(COD). When a time harmonic plane wave was incident on a 2-D isolated crack (slit) of width 2a, the COD distributions were numerically calculated as a function of ka. The calculated COD agreed well with results obtained with other methods. The far-field scattering amplitude, which completely characterizes the flaw response, was calculated in two ways. The Kirchhoff approximation and the BIE-COD exact formulation were compared in terms of incidence angle and frequency ka in a pulse-echo mode. Maximum response was obtained for both methods at the specular reflection direction. Away from the specular direction, the Kirchhoff approximation becomes less accurate. The time domain crack response was also calculated using a band-limited spectrum of center frequency 10 MHz. At oblique incidence to the crack both methods show the existence of an antisymmetric flash points occurring from the crack edge. The Kirchhoff approximation provides an exact time interval between flash points, although it unrealistically gives the same amplitude.

• Clinical and Experimental Reproductive Medicine
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• v.7 no.1_2
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• pp.11-20
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• 1980

Hysterosalpingograms (H.S.G.) have been done for several decades to determine causative factors in female infertility. However, the H.S.G. only reverals uterine cavity and tubal patency or inpatency. The author prefers to find more details in regard to the status and condition of the female reproductive organs and their surrounding tissue as they pertain to infertility. H.S.G. in combination with laparoscopic examination reveals the following results. Preparation and method of performance of H.S.G. during laparoscopy in a healthy reproductive age women are as follows. When laparoscopy is not contraindicated, NPO is ordered with routine bowel preparation. Analgesics administered by injection prior to procedure are valium 10mgs and pethidine 50-100mgs. The radiographic procedure is the same as for any HSG technique. During laparoscopy a solution of 3 to 10 ccs. of 60% hypaque sodium is used. Fluroscopic scout films are obtained A-P and oblique views as well as a delayed check film. 1. Age distribution of primary and secondary infertility in this studies involving tubal factors was as follows: 20-29 age group showed 46% incidence and in the 30-39 age group, 50% incidence. Duration of infertility in this study group was the following: 1-2 years showed 26.7%, 3-5 years 53.8%, and 6-9 years 13.3%. 2. Indications of laparoscopic examination were as follows: Secondary infertility in 35% of the cases, obscure tubal occlusion on previous H.S.G. in 25%, unknown origin in 11.7%, and the remaining cases included pelvic pain, small masses, dysmenorrhea, and uterine anomaly. The laparoscopic examination showed clearly the reproductive organs and the surrounding tissues in the pelvic cavity. The abnormal tubal findings there revealed were tuberculous salpingitis and hydrosalpinx in 10% each, endometriosis and peritubabl adhesions in 6.7% each, biconuate uterus in 3.3%. The remaining 58.3% of the cases showed normal findings. Laparoscopic observation for possible myoma nodules, streak ovary, and peritubal adhesions was also done at this time. 3. Comparative tubal findings in combined H.S.G. and laparoscopic examination revealed the following. Bilateral tubal occlusion was present in 14% (7cases) on laparoscopic examination but on H.S.G. 38% (19 cases) were noted. However, tubal occlusion and peritubal adhesions were found in 26% (13 cases) upon laparoscopy and only 8% (4 cases) on H.S.G. examination alone. Normal pelvic findings were present in 60% (27 cases).

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.3
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• pp.211-219
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• 2014

Closed cracks are difficult to detect using conventional ultrasonic testing because most incident ultrasound passes completely through these cracks. Nonlinear ultrasound inspection using sub-harmonic frequencies a promising method for detecting closed cracks. To implement this method, a sub-harmonic phased array (PA) is proposed to visualize the length of closed cracks in solids. A sub-harmonic PA generally consists of a single transmitter and an array receiver, which detects sub-harmonic waves generated from closed cracks. The PA images are obtained using the total focusing method (TFM), which (with a transmitter and receiving array) employs a full matrix in the observation region to achieve fine image resolution. In particular, the receiving signals are measured using a laser Doppler vibrometer (LDV) to collect PA images for both fundamental and sub-harmonic frequencies. Oblique incidence, which is used to boost sub-harmonic generation, inevitably produces various surface waves that contaminate the signals measured in the receiving transducer. Surface wave interference often degrades PA images severely, and it becomes difficult to read the closed crack's position from the images. Various methods to prevent or eliminate this interference are possible. In particular, enhancing images with signal processing could be a highly cost-effective method. Because periodic patterns distributed in a PA image are the most frequent interference induced by surface waves, spatial frequency filtering is applicable for removing these waves. Experiments clearly demonstrate that the spatial frequency filter improves PA images.