• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1177-1183
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• 2010

In this paper, design of a microstrip-fed, Spidron fractal-shaped slot antenna with circular polarization is represented. The ground plane of the designed antenna has a slot that comprises seven right-angled triangle next to each other in a low. A reflector is placed at the bottom on microstrip feeding line to enhance the antenna gain. The optimized design was conducted by varying a length of the first right-angled triangle, location of feeding line, space between a substrate and a reflector. The proposed antenna was fabricated on a Taconic-RF35 substrate. The entire dimension of the fabricated antenna is $40{\times}40{\times}18.6mm^3$ and the reflector is 18.6 mm away from the ground plane. The measured gain of the fabricated antenna is 6.7 dBi at 4.3 GHz. The measured bandwidths of -10 dB reflection and 3 dB axial ratio are 41 % and 7.4 %, respectively.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.337-345
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• 2020

The purpose of this study was to examine the validity and reliability of the Korean Version of Self-Efficacy Questionnaire (KSE-12), which is used to examine Communication Self-Efficacys for 155 nursing students. To verify the construction factor of the tool, exploratory factor analysis with varimax rotation was performed, resulting in one factors with 12 items. KSE-12 was significantly correlation with GICC (p<.001), and criterion validity was verified. Cronbach's α was .98, showing internal consistency. Therefore, we suggest that it will be useful for the accumulating the evidence data for development of the communication self-efficacy program by using the KSE-12.

• Education of Primary School Mathematics
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• v.20 no.4
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• pp.305-319
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• 2017

In the process of finding the triangle height, 26 students in the 6th grade were surveyed to understand the students' triangle height through the eye movement data and to investigate the cognitive load of the students. As a result, the correctness rate of the pre-test was significantly increased in the post-test, and the frequency and retention of gaze data were smaller in the post-test than in the AOI of each question. The Participants's subjective cognitive load indicated that it was more difficult to understand the concept of rotated triangles compared with upright triangles that were parallel to the ground. More frequent and more retentions in the eye-tracking data were detected in the right triangles and acute triangles by rotating configuration. Eye movement data show that eye tracking technology can provide an objective measure of students' cognitive load for feedback on instructional design.

• Journal of the Korean Chemical Society
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• v.21 no.1
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• pp.3-15
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• 1977

Crystals of salicylaldehyde-4-morpholinothiosemicarbazone, $C_{12}H_{15}O_2N_3S$, are orthorhombic with space group Pna21. Unit-cell dimensions are a = 11.85(5), b = 15.45(5) c = 7.18(3)${\AA}$ with z = 4. Three-dimensional intensity data were collected from the multiple-film equi-inclination Weissenberg photographs taken with $CuK{\alpha}$ radiation. The intensities were estimated visually. The structure was solved by Patterson and Fourier methods and refined by the block-diagonal least-squares methods until the final R value becomes 0.11 for the 1064 observed independent reflections. The morpholine ring has a chair form. The rest atoms of salicylaldehyde-4-morpholinothiosemicarbazone molecule excluding morpholine ring and sulfur atom approximately lie on a plane. The hydroxyl group of the salicylaldehyde and the nitrogen atom of the thiosemicarbazone form an intramolecular hydrogen bond, $O-H{\cdot}{\cdot}{\cdot}N$, of 2.67${\AA}$. The short intermolecular distances all appear to be normal van der Waals contacts.

• Geotechnical Engineering
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• v.2 no.3
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• pp.27-36
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• 1986

To investigate the seepage effect on the compacted backfill of retaining walls, an expriment and an analytical study were carried out First, the expriment was performed with a two-way permeameter newly designed for the do- termination on the degree of permeability anisotropy of compacted soils. As a result, e-log(kz/ky) plot showed a linear relationship, where kz and ky were permeability coefficients for the normal and the parallel directions to the compaction. The degree of permeability anisotropy, kz/ky was 2 to 4 at Dr>90% for sands, regardless of the methods of compaction. The kz/ky of the fine sand was greater than that of the coarse sand. Second, the exprimental results were applied to the extention of Gray's theory for the investigation of the active thrust affected by the seepage of permeability anisotropy. The active thrust was decreased with the increase in the degree of permeability anisotropy, and it It.as a little effect on wall friction.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.171-178
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• 2003

Wing and secondary cracks are unique types of cracks observed in rock masses subjected to uniaxial and biaxial compressive loading conditions. In this study, morphological features of wing and secondary cracks developed in gypsum specimens are investigated in the macro and micro scales. Along the path of wing crack, microtensile cracks are observed. Microtensile cracks coalesce with pores and show branch phenomenon. From the onset of the wing crack, multiple initiations of microtensile cracks are observed. Microtensile cracks show tortuous propagation paths and relatively constant aperture of the cracks during the propagation. It is shown that microtensile cracks propagate by splitting failure. At the micro scale, microfsults are observed in the path of the secondary cracks. Along the path of the secondary cracks, separation of grains and conglomerate grains, oblique microfaults, and irregular aperture of microfault are observed. These features show that the secondary cracks are produced in shear mode. The measured sizes of fracture process zone across the propagation direction near the tip of wing and secondary cracks range from 10$\mu{m}$ to 20$\mu{m}$ far wing cracks and from 100$\mu{m}$ to 200$\mu{m}$ for secondary cracks, respectively.

• The Journal of Engineering Geology
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• v.16 no.4 s.50
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• pp.381-392
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• 2006

The passive surface wave survey using microtremor is conducted in areas of crystalline rock basements to obtain average shear-wave velocity structures to 30 m deep (Vs30), on which the earthquake-resistant design standard is based. Test data were recorded at two sites with triangular and L-shaped arrays for 4 seconds with an sampling interval of 2 ms. The microtremor recorded at a site were analysed using the spatial autocorrelation method to obtain phase-velocity spectra and effects of major factors such as size and shape of away and number of record and receiver were examined. At the other site, shear-wave velocities were derived from VSP and microtremor data separately. The results from these two methods agree to each other reasonably well, indicating that the microtremor method can be an effective geophysical tool to measure Vs30.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.515-524
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• 1998

The purposes of this study were to observe the cavity wall morphology and to evaluate the degree of cavity cleanliness when root-end retrograde cavity preparation was done with ultrasonic diamond instruments. To observe the morphology of retrocavity and to evaluate the degree of cavity cleanliness. root-end resections were done on 20 palatal roots of extracted maxillary first molars after canal filling with gutta-percha. Retrocavities were prepared using either ultrasonic diamond instruments or stainless steel ones of medium power setting of level 6 ($Miniendo^{TM}$, EIE, CA, U.S.A.). Morphology of the cavity. degrees of the remaining canal debris and smear layer were evaluated under the scanning electron microscope. The results were as follows: Cavities prepared with ultrasonic diamond instruments showed scratched appearance of wall, while ultrasonic stainless steel preparation showed hatcheted appearance. Ultrasonic diamond instruments induced more smear layer than stainless steel ones did (p<0.01) in the cavity. However, there was no significant difference in canal debris (p>0.05).

• Journal of the Korean Geotechnical Society
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• v.35 no.7
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• pp.5-14
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• 2019

In this study, a prototype abutment was constructed to establish a safety assessment technique of pier and a series of non-destructive tests using impact load. The surcharge load was loaded from 0 tonf to 2.5 tonf on the prototype abutment, and maximum surcharge load was up to 25 tonf. To analyze the behavior of the piers according to the direction of impact, a total of three types of analysis were performed: the direction of the pier, the direction perpendicular to the pier, and the outer direction of the pier. The height of the impact was also tested at each top and bottom. The measuring instrument used an accelerometer to measure the acceleration response when impacted. Based on the series of experimental results, specific values were calculated according to the direction of an impact and the surcharge load using the Fast Fourier Transform (FFT). In addition, the phase difference was used to analyze the pier from the primary 1st mode to the 4th mode.

• Korean Journal of Psychosomatic Medicine
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• v.26 no.1
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• pp.35-43
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• 2018

Objectives : Effects of multiple trauma are complex and extend beyond core PTSD symptoms. However, few psychological instruments for trauma assessment address this issue of symptom complexity. The Trauma Symptom Checklist-40 (TSC-40) is a self-report scale that assesses wide range of symptoms associated with childhood or adult traumatic experience. The purpose of the present study was to evaluate the validity of the Korean Version of the TSC-40 in a sample of psychiatric outpatients. Methods : Data of 367 treatment-seeking patients with DSM-IV diagnoses were obtained from an outpatient department of psychiatric unit at a university hospital. The diagnoses were anxiety disorder, posttraumatic stress disorder, depressive disorder, adjustment disorder and others. Included in the psychometric data were the TSC-40, the Life events checklist, the Impact of Event Scale-Revised, the Zung's Self-report Depression Scale, and the Zung's Self-report Anxiety Scale. Cronbach's ${\alpha}$ for internal consistency were calculated. Convergent and concurrent validity was approached with correlation between the TSC-40 and other scales (PTSD, anxiety and depression). Results : Exploratory factor analysis of the Korean Version of TSC-40 extracted seven-factor structure accounted for 59.55% of total variance that was contextually similar to a six-factor structure and five-factor structure of the original English version. The Korean Version of TSC-40 demonstrated a high level of internal consistency. (Cronbach's ${\alpha}=0.94$) and good concurrent and convergent validity with another PTSD scale and anxiety and depression scales. Conclusions : Excellent construct validity of The Korean Version of TSC-40 was proved in this study. And subtle difference in the factor structure may reflect the cultural issues and the sample characteristics such as heterogeneous clinical population (including non-trauma related disorders) and outpatient status. Overall, this study demonstrated that the Korean version of TSC-40 is psychometrically sound and can be used for Korean clinical population.