• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.580-586
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• 1996

Gelatinization behavior and morphology of epichlorohydrin-crosslinked potato starches (XPs) were investigated. Native potato starch showed a very steep single stage swlling pattern, but crosslinked starches showed various patterns with the degree of crosslinking. Swelling power, solubility and light transmittance were reduced drastically as the degree of crosslinking increased. Brabender initial pasting temperature and peak temperature of crosslinked starches increased because the crosslinking reinforces the intermolecular net work of the starches. Although the swelling of the potato starch granule was inhibited by crosslinking as compared to that of the native one, Brabender peak viscosities (6.5% w/v, db) were on the order of 2,500 units for the native potato starch, 3,700 for the XP with 2.300 anhydroglucose units per crosslinking (AGU/CL) and 3,400 for the XP with 2,100 AGU/CL, due to the decreased breakdown of the swollen granule resulting from the resistance to heat and shear. The XP with 1,900 AGU/CL, however, did not show the peak viscosity and the viscosity was on the order of 500 units because of the excessive unhibition of the swelling. Unlike the native potato starch, 6.5%(m/v, db) pastes of the crosslinked potato starches could form gels, which could be predicted from the Brabender setback and consistency index. When the degree of crosslinking is low, random contraction and radial swelling of the granule was possible. As the degree of crosslinking increased, morphological change became similar to the single dimensional tangential swelling observed from the lenticular wheat starch. These morphological change during heating in excess water explained the gelatinization behaviors of crosslinked starches tested.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.19-29
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• 2002

The purpose of this study was to compare the polymerization shrinkage and the compressive strength of composite and compomer cured with two different light sources ; conventional halogen-light curing unit and recently-developed plasma arc curing unit. The 'strain gauge method' was used for determination of polymerization shrinkage and the compressive strength was measured by universal testing machine. The results of the present study can be summarized as follows: 1. Filling materials in polyethylene molds showed the initial expansion in the early phase of polymerization. This was followed by the rapid contraction in volume during the first 60 seconds and gradually diminished as curing process continued. 2. The polymerization shrinkage in tooth samples was generally lower than in the mold samples. 3. The generally lower amount of linear polymerization shrinkage was observed in compomer and plasma arc curing unit group when compared to composite and conventional curing unit. 4. The higher compressive strength values was found in composite groups regardless curing methods. The results of this study strongly support the application of plasma arc system and fluoride-containing compomer in the field of clinical pediatric dentistry claiming its effectiveness in curing the esthetic dental materials and the anticariogenic capacity.

• Journal of Biosystems Engineering
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• v.34 no.2
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• pp.127-132
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• 2009

In the working population, muscle fatigue and musculoskeletal discomfort are common, which, in the case of insufficient recovery may lead to musculoskeletal pain. Workers suffering from musculoskeletal pains need to be rehabilitated for recovery. Isokinetic testing has been used in physical strengthening, rehabilitation and post-operative orthopedic surgery. Frequency analysis of electromyography (EMG) signals using the mean frequency (MNF) has been widely used to characterize muscle fatigue. During isokinetic contractions, EMG signals present strong nonstationarities. Hilbert-Haung transform (HHT) and autoregressive (AR) model have been known more suitable than Fourier or wavelet transform for nonstationary signals. Moreover, several analyses have been performed within each active phase during isokinetic contractions. Thus, the aims of this study were i) to determine which one was better suitable for the analysis of MNF between HHT and AR model during repetitive maximum isokinetic extensions and ii) to investigate whether the analysis could be repeated for sequential fixed epoch lengths. Seven healthy volunteers (five males and two females) performed isokinetic knee extensions at $60^{\circ}/s$ and $240^{\circ}/s$ until 50% of the maximum peak torque was reached. Surface EMG signals were recorded from the rectus femoris of the right thigh. An algorithm detecting the onset and offset of EMG signals was applied to extract each active phase of the muscle. Following the results, slopes from the least-square error linear regression of MNF values showed that muscle fatigue of all subjects occurred. The AR model is better suited than HHT for estimating MNF from nonstationary EMG signals during isokinetic knee extensions. Moreover, the linear regression can be extracted from MNF values calculated by sequential fixed epoch lengths (p> 0.0I).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.166-174
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• 2013

QRS detection of ECG is the most popular and easy way to detect cardiac-disease. But it is difficult to analyze the ECG signal because of various noise types. The important problem in recording ECG signal is a baseline wandering, which is occurred by rhythm of respiration and muscle contraction attaching to an electrode. Particularly, in the healthcare system that must continuously monitor people's situation, it is necessary to process ECG signal in realtime. In other words, the design of algorithm that exactly detects QRS region using minimal computation by analyzing the person's physical condition and/or environment is needed. Therefore, baseline wander removing method based on morphological filter for efficient QRS detection method is presented in this paper. For this purpose, we detected QRS through the preprocessing method using morphological filter, adaptive threshold, and window. The signal distortion ratio of the proposed method is compared with other filtering method. Also, R wave detection is evaluated by using MIT-BIH arrhythmia database. Experiment result show that proposed method removes baseline wanders effectively without significant morphological distortion.

• Journal of radiological science and technology
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• v.27 no.2
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• pp.7-12
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• 2004

MDCT is a useful, non-invasive, diagnostic tool in the evaluation of coronary artery disease. However, the image quality is affected by an irregular heart rhythm of the patients. Especially, premature ventricular contraction induced stair-step artifacts in the reconstruction of 2-D or 3-D images of the heart including coronary arteries. In recent, we experienced some improving of the image quality after correcting the PVC. Accordingly, the purpose of our study was to evaluate the effectiveness of the arrhythmia correction method, which was commercially available software, in improving the quality of the reconstruction images of the heart. Image analysis was performed, in consensus, by two radiologists. The scores for image quality were ranked as follows; excellent is 4 (image quality is markedly improved and is helpful in the image evaluation), good is 3 (image quality is mildly improved, but is somewhat helpful in the image evaluation), fair is 2 (image quality is improved and is not helpful in the image evaluation), and poor is 1 (image quality is not improved). We used ANOVA method to evaluate the statistical significant differences in the image qualities among the correction methods of the arrhythmia with below 0.05 of p-value. The method of moving the R-R interval showed statistically significant differences in improving of the image quality in patients with arrhythmia. We concluded that the regulation of R-R interval in patients with arrhythmia was an effective method to improve the image quality in the reconstructions of the MDCT coronary angiograms.

• Korean Journal of Applied Biomechanics
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• v.24 no.2
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• pp.139-149
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• 2014

The purpose of this study was to evaluate the effect of angle change of forefoot's adhesive outsole on the electromyographic activity (EMG) of the erector spinae and selected lower limbs muscle during downhill walking over $-20^{\circ}$ ramp. Thirteen male university students (age: $25.4{\pm}3.9$ yrs, height: $176.2{\pm}5.1$ cm, weight: $717.4{\pm}105.0$ N) who have no musculoskeletal disorder were recruited as the subjects. To assess the myoelectric activities of selected muscles, six of surface EMG electrodes with on-site pre-amplification circuitry were attached to erector spinae (ES), rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), lateral gastrocnemius (LG), and medial gastrocnemius (MG). To obtain maximum EMG levels of the selected muscles for normalization, five maximum effort isometric contraction were performed before the experimental trials. Each subject walked over $0^{\circ}$ and $20^{\circ}$ ramp with three different forefeet's EVA outsole (0, 10, $20^{\circ}$) in random order at a speed of $1.2{\pm}0.1$ m/s. For each trial being analyzed, five critical instants and four phases were identified from the recording. The results of this study showed that the average muscle activities of MG and LG decreased in $20^{\circ}$ shoes compared to $0^{\circ}$ and $10^{\circ}$ ones in the initial double limb stance (IDLS). In initial single limb stance (ISLS) phase, the average muscle activities of ES increased with the angle of forefoot's adhesive outsole, indicating that the increment of shoes' angle induce upper body to flex anteriorly in order to maintain balance of trunk. In terminal double limb stance (TDLS) phase, average muscle activities of TA significantly increased in $20^{\circ}$ outsole compared to $0^{\circ}$ and $10^{\circ}$ ones. There was no external forces acting on the right foot other than the gravity during terminal single limb stance (TSLS) phase, all muscles maintained moderate levels of activity.

• The Journal of Pediatrics of Korean Medicine
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• v.21 no.3
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• pp.33-55
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• 2007

Objectives In the present study, the author intended to investigate whether bojung-ikgitang-gamibang(BJGB) and seonbang-paedoktang(SBPT) significantly affect in vivo and in vitro mucin secretion from airway epithelial cells. Methods In vivo experiment, mice's mucin which is on a hypersecretion of airway mucin, mice's tracheal goblet cells in hyperplasia and mice's intraepithelial mucosubstances were exposed with SO2for3weeks. Effects of orally-administered BJGB and SBPT during 1 week on vivo mucin secretion and hyperplasia of tracheal goblet cells were assessed by using both enzyme-linked immunosorbent assay(ELISA) and staining goblet cells with alcian blue. In vitro experiment, confluent hamster tracheal surface epithelial(HTSE) cells were metabolically radiolabeled with 3H-glucosamine for 24hrs and chased for 30 min in the presence of each agent to figure out the effectiveness of 3H-mucin secretion. Total elution profiles of control spent media and treatment sample through Sepharose CL-4B column were analyzed. The effects of each agent on contractility of isolated tracheal smooth muscle and effects of each agent on MUC5AC gene expression in cultured HTSE cells were investigated. Also, possible cytotoxicities of each agent were assessed by measuring lactate dehydrogenase(LDH) release. Additionally, effects of BJGB and SBPT on both MUC5AC gene expression in cultured HTSE cells and TNF- or EGF-induced MUC5AC gene expression in human airway epithelial cells (NCI-H292) were investigated. Results (1) BJGB and SBPT inhibited hypersecretion of in vivo mucin. SBPT also inhibited the increase the number of goblet cells. However, BJGB did not affect the increase of number of goblet cells; (2) BJGB significantly increased mucin secretion from cultured HTSE cells, without significant cytotoxicity, and chiefly affected the 'mucin' secretion; (3) SBPT did not affect mucin secretion from cultured HTSE cells without significant cytotoxicity, and also did not affect the secretion of the other releseable glycoproteins; (4) BJGB and SBPT did not affect Ach-induced contraction of isolated tracheal smooth muscle; (5) SBPT significantly inhibit the expression levels of MUC5AC gene and BJGB significantly increased the expression levels of MUC5AC gene in both HTSE cells and NCI-H292 cells. Conclusions BJGB and SBPT can not only affect the secretion of mucin but also affect the expression of mucin gene. The author suggests that the effects BJGB and SBPT with their components should be further investigated and it is highly desirable to find from oriental medical prescriptions, novel agents which might regulate hypersecretion of mucin from airway epithelial cells.

• The Journal of Pediatrics of Korean Medicine
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• v.21 no.3
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• pp.109-124
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• 2007

Objectives In the present study, the author intended to investigate whether Gamitonggyu-tang (GTT) significantly affects (since the subject is GTT, you need an 's') in vivo and in vitro mucin secretion from airway epithelial cells. Methods In vivo experiment, mice's mucin which is on a hypersecretion of an airway, mice's tracheal goblet cells in hyperplasia and mice's intraepithelial mucosubstances were exposed with SO2 for 3 weeks. Effects of orally-administered GTT for 1 week on in vivo mucin secretion and hyperplasia of tracheal goblet cells were assessed by using enzyme-linked immunosorbent assay (ELISA) and staining goblet cells with alcian blue. In vitro experiment, confluent hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled with 3H-glucosamine for 24 hrs and chased for 30 min in the presence of GTT to figure out the effectiveness of 3H-mucin secretion. Total elution profiles of control spent media and treatment sample through Sepharose CL-4B column were analyzed.Possible cytotoxicities of each agent were assessed by measuring lactate dehydrogenase (LDH) release. Also, the effect of GTT on contractility of isolated tracheal smooth muscle was investigated. Results (1) GTT inhibited hypersecretion of in vivo mucin. However, it did not affect the increase the number of goblet cells (2) GTT significantly increased mucin release from cultured HTSE cells, without significant cytotoxicity (3) GTT chiefly affected the 'mucin' secretion and did not affect the secretion of the other releasable glycoproteins with less molecular weight than mucin (4) GTT did not affect Ach-induced contraction of isolated tracheal smooth muscle.Conclusions This result suggests that GTT can increase mucin secretion during short-term treatment (in vitro) whereas it can inihibit hypersecretion of mucin during long-term treatment (in vivo). The author suggests that the effect GTT with their components should be further investigated and it is valuable to find from oriental medical prescriptions, novel agents which might regulate mucin secretion from airway epithelial cells.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.4
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• pp.365-376
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• 2021

In general, domestic streams and rivers are composed of alluvial rivers consisting of sand and gravel beds. These rivers can cause erosion and riverbed changes due to sudden changes in flow rates, such as floods, torrential rains, and heavy rains. In particular, there are various types of erosion, such as contraction erosion caused by changes in river shape, or local erosion occurring around obstacles such as piers, abutments or embankments. In addition, river changes can occur in various forms, such as static or dynamic periods, due to limitations such as flow rate, velocity, and shear stress. This study focused on the erosions of embankments directly related to human casualties among various river structures, and evaluated limit velocities and critical shear stress in order to identify changes in strength of natural materials by identifying the characteristics of natural hoan materials and resistance to erosions. In particular, the limitations of materials according to the type of materials in the river, characteristics of particles, and size of particles were studied using Soil loss, which is a change in the volume of the revetment material, and it is intended to be used as basic data for river design and restoration.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.685-691
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• 2022

This study was based on the steel composite concrete box structure (Transfer girder) which was installed to support the skyscrapers directly above the subway line. In this study, it was analytically proved that the cause of cracks on the steel composite concrete box structure were the shrinkage cracks by comparing the results of crack investigation and numerical analysis. As the results, it was found that the internal temperature difference between concrete and steel members occurred according to the shape of the steel frame embedded in concrete, the location of vertical stiffener, and the closed section area. The narrower spacing of vertical stiffener was occurred the internal temperature concentration of the structure and the temperature difference increased. And the location of higher thermal strain and temperature were similar to the location of actual cracks by the visual inspection. Therefore, the internal temperature concentration parts were formed according to the presence and spacing of the vertical stiffeners and the inspection passage in the central part of the structure. The shrinkage cracks were occurred by the restrained of temperature expansion and contraction of the concrete. As the results of this study, it was important to separate and manage the non-structural cracks caused by shrinkage and the structural cracks in the maintenance of serviced steel-composite concrete structures.