• Journal of the Korean Geotechnical Society
• /
• v.21 no.4
• /
• pp.71-81
• /
• 2005

Surface wave techniques were initially based on 2-D plane waves and were later improved to the techniques based the 3-D based cylindrical waves. However, body-wave interference, near-field effect and limited technology in surface wave measurements restricted the use of 3-D cylindrical waves to the 1-D evaluation of subgrade stiffness. In this study, by the numerical simulation of SASW measurements, the dispersion properties of surface waves including vertical, horizontal Rayleigh waves and Love waves were thoroughly investigated in the 3-D domain, and a new filter criteria to minimize the near-field effect was established, which led to CAP (common-array-profiling)-SASW technique. The CAP-SASW technique enabled the evaluation of subgrade stiffness fur a specific subgrade segment, not for a whole section of measurement array. Therefore, a contour plot of subgrade stiffness with a ground-truth quality can be obtained by the CAP-SASW technique. The procedure proposed in this study was verified by comparing the shear-wave velocity profiles with the shear-wave velocity profiles of downhole testing at two geotechnical sites.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.4
• /
• pp.5-12
• /
• 2005

Recently, geophysical prospecting methods have played very important roles in civil and environmental engineering problems. Technical advances in geophysical instruments and computer system made it possible to get underground images with very high resolution far purposes to resolve those problems. It was possible partly due to ever increasing demand for development of technologies needed to precisely detect polluted areas and prevent ground-related accidents. Based on the same demand, integrity tests of cast-in place piles draw more attention and development of accurate test procedures is required. Ultrasonic methods is one of most advanced non-destructive procedures. In the paper, a geotomography method is employed for the cast-in place pile integrity test using ultrasonic waves. The image of pile interior is scanned and scrutinized far better and more accurate decision in the cast-in place pile integrity. In this study, we firstly examined the accuracy fur tomography program with idealized synthetic models built in water tank: their position and size were changed in the tank and each case was studied. In the next stage, real concrete pile models were fabricated and images of anomaly areas inside the pile were scanned to successfully locate those areas.

• Journal of the Korea Institute of Building Construction
• /
• v.11 no.3
• /
• pp.229-237
• /
• 2011

The pullout test is a nondestructive testing method certified by the American Society for Testing and Materials (ASTM) and British Standards (BS). Research has shown that it is very reliable in terms of evaluating the concrete strength of reinforced concrete members. However, the pullout test is rarely performed on domestic construction sites due to the complex procedures and high costs involved. This study proposes a new pullout test composed of a post installable break-off bolt, an insert nut, and a pullout tester, which satisfy both economical and practical purposes on a construction site. Three different types of special fastening methods, a temporary fixed bolt, a plastic fixed panel, and a fixed bar, have been developed. A pullout tester is proposed that is driven by the circle force introduced into a handle composed of eight gears without a load cell and a hydraulic cylinder. The serviceability and reliability of these instruments were investigated through experiments at construction sites. Furthermore, the sample pullout test with a wall specimen was conducted to estimate the usefulness of the temporary fixed bolt type of fastening methods and pullout devices. Eventually, the developed instruments will be useful on construction sites if minor requirements are met.

• The Journal of Engineering Geology
• /
• v.29 no.4
• /
• pp.553-563
• /
• 2019

In order to survey archaeological sites, drilling and excavation are carried out at the final stage. However, at the preliminary stage, non-excavation geophysical prospection is used for assessing underground archaeological ruins. Among the geophysical prospecting techniques, Ground Penetration Radar (GPR) prospection has effectively been applied to historical sites due to its high resolution at shallow depths. In this study, the GPR prospection was conducted to find underground ruins near Suseong-Dang, the place of ancient rituals in Buan area, Korea. First, the GPR prospection was conducted at three sites (Site-1, 2, and 3), and subsequently, the GPR prospection was carried out at Site-3 in more detail. As a result of the prospection, the underground layered structure of the survey area consists of three layers, which are soil layer, weathered rock, and sound rock from the surface. And the GPR anomaly to the archaeological structure was clearly identified at around 100-cm depth showing est-west direction that is parallel to the long-axis array. This GPR anomaly of irregular geomorphological features and intermittent distribution may be related to the ritual remains found in Suseong Dang. The GPR prospection could be effectively used to detect archaeological sites or remains buried in the ground.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.51 no.5
• /
• pp.451-457
• /
• 2006

The purpose of this study is to measure fundamental data required for the prediction of rice quality and to develop regression models to predict protein, amylose, moisture and fatty acid contents, and Toyo taste meter value (TTMV) of brown and polished rice from hulled rice NIR spectra. NIR spectra of hulled rice measured in transmittance mode (850-1050 nm) and in reflectance mode (400-2500 nm) were used to predicted chemical compositions of brown rice and polished rice. For most chemicals, the transmittance spectra could provide better calibration results than the reflectance ones. Beside the Toyo taste meter value (TTMV), the hulled rice spectra could predict chemical contents with the determination coefficients higher than 0.8. Spectra of hulled rice measured in transmittance mode could be used for the prediction of chemical compositions in brown rice and polished rice precisely. However, taste value of polished rice was a constituent that was hardly to be predicted.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.49 no.6
• /
• pp.463-467
• /
• 2004

This study was carried out to estimate of leaf area index (LAI) rapidly using plant canopy analyzer, comparing with specific leaf area (SLA) and leaf area ratio (LAR) in rice from 2001 to 2002 at Honam Agricultural Research Institute in Iksan Korea. The relationship between LAI values taken by plant canopy analyzer and by leaf area meter showed high correlation at each growth stages of rice. LAIs obtained by plant canopy analyzer were highly correlated with that by leaf area meter which were the highest in Dongjinbyeo and the lowest in Hapcheon1. Specific leaf area (SLA) of all rice cultivars were tend to decrease remarkably with the progress of growth stage. It was found that the SLA of Dasanbyeo was the highest and that of Hapcheon1 was the lowest among rice cultivars tested. Leaf area ratios (LARs) was also decreased with the progress of growth stage.

• Journal of Korean Society of Steel Construction
• /
• v.24 no.1
• /
• pp.23-34
• /
• 2012

In this study, stub columns subjected to concentrical and eccentrical loads were tested to check the applicability of the current local stability criteria (KBC2009, AISC2005) to 800MPa high-strength steel (HSA800). The key test variables in the concentrically loaded tests included the plate-edge restraints and the width-to-thickness ratio normalized by the yield strength of steel. Specimens made of ordinary steel (SM490) were also tested for comparative purposes. Eccentrically loaded stub column tests were conducted for a range of the P-M combinations by controlling the loading eccentricity. All the concentrically loaded specimens with non-compact and slender sections developed sufficient strengths according to the current local stability criteria. All the eccentrically loaded specimens with non-compact H sections also exhibited a sufficient P-M interaction strength that was even higher than that of compact H- section counterparts. Residual stresses were also measured by using the non-destructive indentation method to demonstrate their dependency or independency on the steel material's yield strength. The measured results of this study also indicated that the magnitude of residual stresses bears no strong relation to the yield strength of the steel material.

• Korean Journal of Materials Research
• /
• v.10 no.9
• /
• pp.601-606
• /
• 2000

Nickel mono-silicide(NiSi) shows no increase of resistivity as the line width decreases below 0.15$\mu\textrm{m}$. Furthermore, thin silicide can be made easily and restrain the redistribution of dopants, because NiSi in created through the reaction of one nickel atom and one silicon atom. Therefore, we investigated the deposition condition of Ni films, heat treatment condition and basic properties of NiSi films which are expected to be employed for sub-0.15$\mu\textrm{m}$ class devices. The nickel silicide film was deposited on the Si wafer by using a dc-magnetron sputter, then annealed at the temperature range of $150~1000^{\circ}C$. Surface roughness of each specimen was measured by using a SPM (scanning probe microscope). Microstructure and qualitative composition analysis were executed by a TEM-EDS(transmission electron microscope-energy dispersive x-ray spectroscope). Electrical properties of the materials at each annealing temperature were measured by a four-point probe. As the results of our study, we may conclude that; 1. SPM can be employed as a non-destructive process to monitor NiSi/NiSi$_2$ transformation. 2. For annealing temperature over $800^{\circ}C$, oxygen pressure $Po_2$ should be kept below $1.5{\times}10^{-11}torr$ to avoid oxidation of residual Ni. 3. NiSi to $NiSi_2$ transformation temperature in our study was $700^{\circ}C$ from the four-point probe measurement.

• Conservation Science in Museum
• /
• v.13
• /
• pp.13-22
• /
• 2012

The patterns for Jeogui and Pyeseul (patterns of the queen's ceremonial robe worn and a belt ornament covering knees in the front) as owned by National Museum of Korea were made in the early 20th century and both of them were colored on paper. Through a non-destructive analysis on pigments and dyes used on both the patterns, it was attempted to identify the coloring materials. As for the analysis of the coloring pigments, the XRF was used. As a result of the pigment analysis on the pattern for Jeogui, it is presumed that lead white was used for obtaining the white color, ink stick for black color, orpiment for yellow color, cinnabar and red lead for red color, copper and arsenical or a mixture of copper carbonate and orpiment for green color whereas brass seems to have been used for obtaining other colors. The pigments used for obtaining the colors of white, black, yellow and green on the pattern for Pyeseul are the same as those used on the pattern for Jeogui whereas the red pigments used on each of the two patterns are seen to be different. Although it may be difficult to identify the kinds of blue pigments that were used on the patterns for Jeogui and Pyeseul, a mixture containing lead white is presumed to be used as blue pigment. Also, as a result of the UV-Vis spectroscopic analysis performed on the blue hanji (traditional Korean paper) of the pattern for Jeogui, it was presumed to have been dyed with indigo.

• Conservation Science in Museum
• /
• v.13
• /
• pp.51-58
• /
• 2012

The Conservation Science Team of the National Museum of Korea has carried out the conservation on the mandolin-type bronze sword that was excavated from Weolnae-dong, Yeosu as had been requested by the Research Center of Dolmens in Northeast Asia. The mandolin-type bronze sword from Weolnae-dong, Yeosu is accounted to be the longest one among all the bronze swords of the same type that have ever been excavated until now and it was in a treated condition with the primary conservation treatment already achieved. Due to the corrosion in progress, it was in a very brittle condition being in two separate parts of the upper and lower parts. With the upper part exposed and the lower part with earth, they were urgently collected. The Conservation Science Team carried out the conservation treatment on them by connecting the lower part of the mandolin-type bronze sword to the upper part after making the lower part exposed, and then by using an estimated restoration method for lost portions. When carrying out the conservation treatment, the glass fibers of 10 wt% Paraloid B-72 (in Xylene) was used as a method for strengthening the brittle artifact, and a non-destructive analysis was carried out to identify the ingredients using the X-ray fluorescence spectrometer.