• Restorative Dentistry and Endodontics
• /
• 제46권3호
• /
• pp.39.1-39.12
• /
• 2021

Objectives: This study analyzed the physical-chemical behavior of 2 bulk fill resin composites (BFCs; Filtek Bulk Fill [FBF], and Tetric-N-Ceram Bulk Fill [TBF]) used in 2- and 4-mm increments and compared them with a conventional resin composite (Filtek Z250). Materials and Methods: Flexural strength and elastic modulus were evaluated by using a 3-point bending test. Knoop hardness was measured at depth areas 0-1, 1-2, 2-3, and 3-4 mm. The translucency parameter was measured using an optical spectrophotometer. Real-time polymerization kinetics was analyzed using Fourier transform infrared spectroscopy. Results: Flexural strength was similar among the materials, while TBF showed lower elastic modulus (Z250: 6.6 ± 1.3, FBF: 6.4 ± 0.9, TBF: 4.3 ± 1.3). The hardness of Z250 was similar only between 0-1 mm and 1-2 mm. Both BFCs had similar hardness until 2-3 mm, and showed significant decreases at 3-4 mm (FBF: 33.45 ± 1.95 at 0-1 mm to 23.19 ± 4.32 at 3-4 mm, TBF: 23.17 ± 2.51 at 0-1 mm to 15.11 ± 1.94 at 3-4 mm). The BFCs showed higher translucency than Z250. The polymerization kinetics of all the materials were similar at 2-mm increments. At 4-mm, only TBF had a similar degree of conversion compared with 2 mm. Conclusions: The BFCs tested had similar performance compared to the conventional composite when used in up to 2-mm increments. When the increment was thicker, the BFCs were properly polymerized only up to 3 mm.

• Korean Journal of Radiology
• /
• 제22권1호
• /
• pp.97-105
• /
• 2021

Objective: The present study aimed to investigate the association between myocardial blood flow (MBF) quantified by dynamic CT myocardial perfusion imaging (CT-MPI) and the increments in heart rate (HR) after stress in patients without obstructive coronary artery disease. Materials and Methods: We retrospectively included 204 subjects who underwent both dynamic CT-MPI and coronary CT angiography (CCTA). Patients with more than minimal coronary stenosis (diameter ≥ 25%), history of myocardial infarction/revascularization, cardiomyopathy, and microvascular dysfunction were excluded. Global MBF at stress was measured using hybrid deconvolution and maximum slope model. Furthermore, the HR increments after stress were recorded. Results: The median radiation dose of dynamic CT-MPI plus CCTA was 5.5 (4.5-6.8) mSv. The median global MBF of all subjects was 156.4 (139.8-180.4) mL/100 mL/min. In subjects with HR increment between 10 to 19 beats per minute (bpm), the global MBF was significantly lower than that of subjects with increment between 20 to 29 bpm (153.3 mL/100 mL/min vs. 171.3 mL/100 mL/min, p = 0.027). This difference became insignificant when the HR increment further increased to ≥ 30 bpm. Conclusion: The global MBF value was associated with the extent of increase in HR after stress. Significantly higher global MBF was seen in subjects with HR increment of ≥ 20 bpm.

• 한국해양학회지:바다
• /
• 제8권3호
• /
• pp.237-242
• /
• 2003

실험실에서 황복을 부화 후 1일에서 63일까지 사육하면서 표본을 추출하여 황복의 초기성장과 이석의 미세구조 관찰하였다. 부화 당시 황복의 전장은 3.09$\pm$0.02 mm였으며, 부화 후 10일에 전장 4.96$\pm$0.24 mm, 20일에는 5.39$\pm$0.42 mm, 30일에는 9.13$\pm$0.59 mm로 성장하였고, 부화 후 34일에는 평균 10.78$\pm$0.96 mm로 성장하였으며, 부화 후 43일에는 16.40$\pm$2.31 mm, 부화 후 63일에는 30.49$\pm$1.53 mm로 성장하였다. 부화한 황복 이석의 평균 장반경은 14.20$\pm$1.21 $\mu\textrm{m}$였고, 부화 후 10일째는 31.06$\pm$2.31 $\mu\textrm{m}$, 20일째는 57.19$\pm$6.19 $\mu\textrm{m}$, 34일째는 127.13$\pm$13.13 $\mu\textrm{m}$, 43일째는 190.79$\pm$17.08 $\mu\textrm{m}$, 63일째는 281.85$\pm$23.81 $\mu\textrm{m}$로 부화 후 20일 이후의 이석의 크기변화는 체장의 성장 경향과 유사하였다 황복의 이석에는 다른 성장선들과 구별되는 부화정지선이 형성되어있으며, 부화정지선 형성이전에 2-3개의 미세성장선이 관찰되었다. 부화 후 20일부터 63일까지, 황복의 이석에 형성된 일일성장선의 수와 경과한 일수는 1차 비례관계를 보였으며, 하루에 한 개씩 형성되어지는 것이 확인되었다.

• 충청수학회지
• /
• 제9권1호
• /
• pp.115-121
• /
• 1996

Let $\{X(t);\;t{\in}R^n\}$ be a measurable, separable and H-sssis random fields. Here, we suppose that the increments are invariant under all Euclidean rigid body motions. We investigate some properties of H-sssis random fields and monotonicity of projection process $\{X_e(t);\;t{\in}R^1\}$ in any direction $e{\in}R^n$.

• 충청수학회지
• /
• 제5권1호
• /
• pp.23-34
• /
• 1992

This is an extension of results of Wiener's nonlinear noise theory from noises generated by the Wiener process to noises generated by processes with stationary Gaussian increments. In particular, using Nisio's Approach, we show that every measurable ergodic noise can be approximated in law by Gaussian process-presentable noise.

• Journal of the Korean Statistical Society
• /
• 제22권1호
• /
• pp.93-111
• /
• 1993

Let ${X(t) : t \geq 0}$ be a real-valued stochastics process with stationary independent increments. In this paper, under the condition of stochastic compactness, we obtain appropriate function $\alpha(t)$ and random function $\beta(t)$ such that for some positive finite constant C, lim sup${X(t) - \alpha(t)}/\beta(t) = C$ a.s. both as t tends to zero and infinity.

• 대한치과교정학회지
• /
• 제17권2호
• /
• pp.215-221
• /
• 1987

This study was designed to investigate the growth amount and rate of mandible by the measurements of mandibular lateral surface and the relationship of peak growth increments between mandible and body height The sample consisted of twenty-five boys and fifteen girls between the ages of 6 and 13 The surface of mandible was measured from digitized roentgenocephalometric analysis (A 27 point mandibular model) The findings of this study can be summarized as follows 1 No significant difference was found between mandibular lateral surfaces of the both sexes at the ages studied. 2 The mean growth amount of mandibular lateral surface from 6 to 13 years of ages was $9\;09cm^2$ in boys and $8\;29cm^2$ in girls, and the mean growth rate was 46 07% in boys and 42 57% in girls 3 The prepubertal peak growth increment in mandible was found between the ages of 11-12 in girls and 12-13 in boys 4 The prepubertal peak growth increments of mandible occured one year later that of body height in boys and girls.

• 한국환경과학회지
• /
• 제3권1호
• /
• pp.57-64
• /
• 1994

On the basis of the principle of Bratch's electronegativity equalization, we calculated group partial charges and group electronegativities for nonionic surfactants with Pauling's elecoonegativity parameters by using numerical calculation method. From calculated outputs we have investigated structural stability of micelle, characteristics of hydrophilic and hydrophobic groups, and relation between CMC(Critical Micelle Concentraion) and group partial charge and group electronegativity of hydrophilic and hydrophobic groups for nonionic surfactants. We have known that CMC by micelle formation depends upon group partial charge and group electronegativity of hydrophilic and hydrophobic groups for surfactants. Also, the structural stability of micelle in H2O solution is related to the electric double layer by the hydrophilic group of nonionic surfactants with H atoms in water CMC is diminished by the decrease of repeating units in hydrophilic group at constant hydrophobic group and is diminished by the increments of alkyl chains in hydrophobic group at constant hydrophilic group for nonionic surfactants. In conclusion, CMC is diminished because there is no electrostatic repulsion and is diminished of Debye length by the increments of partial charge of hydrophobic group.

• 대한물리의학회지
• /
• 제6권4호
• /
• pp.497-504
• /
• 2011

Purpose : Chronic cervical pain is a common source of disability in society. There has been no research regarding the amount of pressure for the deep cervical flexors during cranio-cervical flexion exercise (CCFE). The purpose of this study is to determine optimal pressure levels to facilitate deep cervical muscles (longus colli & longus capitis) during cranio-cervical flexion exercise, using ultrasound measurement of the muscles. Methods : Using a cross-sectional design, the study was performed in an experimental group of 19 subjects (7 men, 12 women) with no cervical pain. Participants were instructed to perform the CCFE, and during the five incremental stages of the test, changes in thickness, as compared to resting baseline values, were measured using ultrasonography for sternocleidomastoid muscle (SCM) and deep cervical muscles (DCF). Results : Both DCF and SCM muscles demonstrated an increase in recruitment with each progressive phase of the test. In comparing the different pressure increments, the most significant changes found in DCF thickness were between phase 2 and phase 3 (p<.05). However no differences were found between pressure increments for SCM thickness (p>.05). Conclusion : The results suggest 26 mm Hg as the optimal pressure level during cranio-cervical flexion exercise for facilitation of deep cervical flexor.

• 한국생활과학회지
• /
• 제14권1호
• /
• pp.107-117
• /
• 2005

The purpose of this study is to develop the size and grading increments chart for the middle-aged obese women compared with normal women in middle age. Seven hundred and thirty three women's data from the 4th National Korean Size Survey for Standardization (1997) were analyzed. It was found that size increment of bust and hip girth of obese women was different from that of ordinary middle-aged women. The rate of coverage for a certain set of size specification and the grading increment value for the clothing of Korean obese women in middle aged group were also suggested. The relative percentage value of grading rule based on the change in bust girth increment of Korean obese women was quite different from that of American women. In conclusion, it was noted that the characteristics of the body size specification of obese women was quite different from those of the corresponding age group, so that the separated size specification and grading rule are needed to be used in the manufacturing process of obese women's clothing.