• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.4
• /
• pp.391-397
• /
• 2017

Recently, digital image correlation (DIC) techniques have been used to measure dynamic deformation during tensile testing. The standard tensile test method measures the average displacement of the relevant specimen to calculate the true stress-strain curve. Therefore, the validity of the true stress curve is restricted to the stress incurred within the uniform stretching interval, i.e., the maximum stress corresponds to the starting point of the necking deformation. Alternatively, if DIC is used, the effective range of the strain and strain rate can be extended to the breaking point of the tensile specimen, because of the feasibility of measuring the local strain over the entire area of interest. Because of these advantages, many optical 3D measurement systems have been introduced and used in research and industry. However, the conventional 3D measurement systems are exceedingly expensive and time consuming. In addition, these systems have the disadvantage of a very large equipment size which makes their transport difficult. In this study, a 2D image correction method employing a 2D DIC measurement method in conjunction with a numerical analysis method is developed using a smartphone. The results of the proposed modified 2D DIC method yielded higher accuracy than that obtained via the 3D measurement equipment. In conclusion, it was demonstrated that the proposed 2D DIC and calibration methods yield accurate measurement results with low time costs.

• Korean Journal of Environmental Biology
• /
• v.35 no.3
• /
• pp.389-397
• /
• 2017

The purpose of this study was to investigate the characteristics of species by comparing the external shape traits and skull size of Tscherskia triton in Jeju Island from May 2014 to November 2016. Body weight, head-body length, ear length, and hind-foot length were not statistically significant (p>0.05), but tail length was statistically significant in females compared to males (p=0.003). To examine the secondary sexual dimorphism characteristics of the collected T. triton, B_HR, T_HR, E_HR, and H_HR were calculated based on the head-body length, and only T_HR was statistically significant (p=0.003). Because of comparing male and female averages, among the 21 traits, the greatest length of skull (GLS; p=0.020) and occipitonasal length (ONL; p=0.014) were statistically significant and length of incisive foramen (LIF) was statistically significant, when the significance level was 90%. However, the other 18 traits did not show statistically significant differences between males and females (p>0.05). Other than GLS, ONL, interorbital breadth (IB), and breadth of occipital foramen (BOF), there was female-biased SSD. The results of this study are the analysis of external morphology and skull characteristics of T. triton in Jeju Island and will be used as basic data to understand the morphological characteristics of T. triton. In addition, the data can be used as a basic information to compare characteristics of T. triton, which is known as a single species, inhabited in China and Russia. The data will play an important role in biogeography and ecology research of T. triton, based on geographical conditions, climate effects, and habitat environment.

• Korean Journal of Microbiology
• /
• v.51 no.4
• /
• pp.389-397
• /
• 2015

Dongchun, one of the representative streams in urban area, is a downstream that is connected to Hogyechun, Bujeonchun, Jeonpochun, Danggamchun, and Gayachun as its upstream. Hogyechun has been mostly covered with concrete structures for decades, causing sewage pollution from the upstream, overflow of the downstream region and other serious pollution that gave rise to many civil complaints from the residents nearby. In this study, we analyzed 3 stations, including control station for water quality and malodor changes of Hogyechun after applying the microbial augmentation (BM-2) for a few months including the rainy season. Amounts (g/h) of DO in the middle site (Middle) and the downstream site (Borim) increased by 1.7 times compared with the upstream site (Chuhae) after augmentation for about 2 months. Amounts (g/h) of COD and $NO_3{^-}N$ decreased by 2 and 1.7 times, respectively, in the middle and downstream sites while SS increased by 7.5 and 22 times in the middle and downstream sites, respectively. Moreover, odor removal efficiencies at the middle and downstream sites were 65% and 19%, respectively, indicating the microbial activity in reduction of malodor in the polluted stream. The dominant microbial species of the sampling sites were Hydrogenophaga caeni, Sphaerotilus natans, Acidovorax radicis, Acidovorax delafieldii, and Cloacibacterium rupense. Densities of the two species Sphaerotilus natans and Acidovorax delafieldii were significantly increased in the middle site after augmentation which possessed potential odor removal and denitrification activity, respectively. Potential pathogens (e.g., Arcobacter cryaerophilus) were also removed from the middle site after the implementation.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.16 no.2
• /
• pp.18-24
• /
• 2012

Purpose : Although lung ventilation SPECT (LV-SPECT) has a good sensitivity in detection of deep lung lesions, it is difficult to apply the LV-SPECT to patients having breathing problems due to limited examination time. In this study, we evaluated the usefulness of LEAP collimator, which provides high detection sensitivity and tolerable resolution, for the LV-SPECT in terms of diagnostic accuracy and examination time. Materials and Methods : Four volunteers inhaled Technegas (370 MBq) and the lung ventilation planar scan (LVPS, 300 counts/view (cpv)) with LEHR collimator was performed using Siemens E.cam scanner as a reference test. LV-SPECT scans were performed with three collimators, LEHR, LEUHR, and LEAP, in low (7 kcpv) and high (70 kcpv) counting modes. The count ratios of left (LT) and right (RT) lung segments were calculated on the geometric mean view of anterior and posterior images for LVPS and on the summed coronal images of LV-SPECT, respectively. Comparing to LVPS, the usefulness of three different collimators for LV-SPECT was evaluated through statistical analysis (paired t-test), on count ratios of lung segments. Results : The average LT:RT ratio in LVPS was 47:53. For LV-SPECT, there were negligible difference of the LT:RT ratios (48:52 on average) among three different collimators in low and high counting modes. Comparing to standard LVPS with LEHR, all LV-SPECTs with different collimators resulted in similar diagnostic accuracy through paired t-test (p>0.05). The scan time in LVPS (6 views) was 17.3 min. For LV-SPECT (128 views) in low counting mode, it took 18.7 (LEUHR), 15.0 (LEHR), and 12.3 min (LEAP), respectively. Conclusion : Comparing to standard LVPS, the LV-SPECT with LEAP in low counting mode provided the comparable diagnostic accuracy in addition to shortened scan time.

• The korean journal of orthodontics
• /
• v.29 no.3 s.74
• /
• pp.383-397
• /
• 1999

Bone is a dynamic tissue which is constantly remodelled by subsequent cycles of bone resorption and formation. Glucocorticoid and vitamine $D_3$ are known as regulating substances in bone metabolism. In vitro experiments using bone tissue, it was suggested that glucocorticoid inhibits bone resorption, whereas the effect of glucocorticoid on bone formation are complex- increasing or decreasing effect. The active form of vitamin $D_3$, 1,25-dihydroxycholecalciferol[1.25-$(OH)_2D_3$], has been reported to stimulate osteoblastic activities including the production of ALP, type I collagen, and osteoclacin. The purpose of this study was to evaluate the effect of admixture of vitamin $D_3$ and dexamethasone, one of glucocorticoids, on osteoblastic cell line(MC3T3-E1). Alkaline phosphatase(ALP) and MTT assay were conducted in the cultivated cells with 1, 10, 100nM/ml of 1,25-$(OH)_2D_3$ and/or 10nM/ml, 100nM/ml, $1{\mu}M/ml$ of dexamethasone. The observed results were as follows. 1. The activity of osteoblastic cells with $1{\mu}M/ml$ of dexamethasone was significantly increased at 1-day cultivation with comparison to control group, but was decreased afterwards. But the activity of ALP was greatest in $1{\mu}M/ml$ of dexamethasone and increased with time lapsed. 2. The activity of osteoblastic cells with vitamin $D_3$ was significantly increased dose-dependently at 1-day cultivation, but was significantly decreased in l00nM/.ml at 2-day cultivation, and was a little increased again at 3-day cultivation. The activity of ALP was increased in 10nM/ml or 100nM/ml at 2-day or 3-day cultivation, and was greatest in 100nM/ml at 3-day cultivation. 3. In case of admixture of dexamethasone and vitamin $D_3$, the cellular activity was decreased in any concentration of vitamin $D_3$ at 2-day cultivation, but was increased again at 3-day cultivation, which was greater than that in control or dexamethasone only group. The activity of ALP was decreased at 1-day cultivation, but was increased in the admixture of 10nM/ml or 100nM/ml of dexamethasone with 100nM/ml of vitamin $D_3$ at 2-day cultivation, and was again decreased at 3-day cultivation.

• Journal of Korean Society of Forest Science
• /
• v.76 no.4
• /
• pp.397-409
• /
• 1987

This study was executed to analyze the user's impact on vegetation structure changes and user's psychology in Odongdo Island of Hallyo-Haesang National Park. Five sites were sampled for vegetation structure changes vi the study area according to the extent of impact observed. Also user's psychology was studied through questionnaire with the visitors and 366 answers were collected at random sampling in May, 1986. Evergreen broad-leaved forest, i.e. Machilus thunbergii, Cinnamomum camphora, and Camellia japonica forest, took possession of 32.5% (3.91ha) of total forest area when condisering the actual vegetation. Camellia japonica community covered 40.0% (4.72ha) and Sasa coreana community took possession of 41.8% (5.02ha). The area of environmental impact grade 3 and 4 area covered 44.3% of total forest area and it should be restored because self-repair seemed to be impossible. The evergreen broad-leaved forest was destoryed seriously with no younger trees in middle and lower layers by overuse impact and would be bared soon. So the preservation of autochthonous flora is required by the control of the number of users. It was shown that most of visitors come on holidays and Sunday and places which were favorably impressed were shown as the area of showing the sea and Camellia forest. Overall levels of satisfaction was comparatively low, consequently 55% of visitors were satisfied. This level of satisfaction was associated with number of users, landscape of forest and number of facilities.