• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.5
• /
• pp.627-635
• /
• 2019

A programmable drone is a drone developed not only to experience the basic principles of flight but also to control drones through Arduino-based programming. Due to the nature of the training drones, the main users are students who are inexperienced in controlling the drones, which often cause frequent collisions with external objects, resulting in high damage to the drones' frame. In this study, the structural stability of the drone was evaluated by means of a structural dynamics based collision simulation for educational drone frame. Collision simulations were performed on three cases according to the impact angle of $0^{\circ}$, $+15^{\circ}$ and $-15^{\circ}$, using an analytical model with approximately 240,000 tetrahedron elements. Using ANSYS LS-DYNA, which provides excellent functions for the simulation of the dynamic behavior of three-dimensional structures, the stress distribution and strain generated on the drone upper, the drone lower, and the ring assembly were analyzed when the drones collided against the wall at a rate of 4 m/s. Safety factors resulting from the equivalent stress and the yield strain were calculated in the range of 0.72 to 2.64 and 1.72 to 26.67, respectively. To ensure structural stability for areas where stress exceeds yield strain and ultimate strain according to material properties, the design reinforcement is presented.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.18 no.2
• /
• pp.3-10
• /
• 2008

The choice of basis for representation of element in $GF(2^m)$ affects the efficiency of a multiplier. Among them, a multiplier using redundant representation efficiently supports trade-off between the area complexity and the time complexity since it can quickly carry out modular reduction. So time of a previous multiplier using redundant representation is faster than time of multiplier using others basis. But, the weakness of one has a upper space complexity compared to multiplier using others basis. In this paper, we propose a new efficient multiplier with consideration that polynomial exponentiation operations are frequently used in cryptographic hardwares. The proposed multiplier is suitable fer left-to-right exponentiation environment and provides efficiency between time and area complexity. And so, it has both time delay of $T_A+({\lceil}{\log}_2m{\rceil})T_x$ and area complexity of (2m-1)(m+s). As a result, the proposed multiplier reduces $2(ms+s^2)$ compared to the previous multiplier using equally-spaced polynomials in area complexity. In addition, it reduces $T_A+({\lceil}{\log}_2m+s{\rceil})T_x$ to $T_A+({\lceil}{\log}_2m{\rceil})T_x$ in the time complexity.($T_A$:Time delay of one AND gate, $T_x$:Time delay of one XOR gate, m:Degree of equally spaced irreducible polynomial, s:spacing factor)

• Composites Research
• /
• v.34 no.4
• /
• pp.233-240
• /
• 2021

VaRI(Vacuum assisted Resin Infusion) process, which is cost effective and suitable for manufacturing large-sized composites, is an OoA(Out-of Autoclave) process. For rapid resin infusion in the VaRI process, a DM(distribution media) is placed on top of the fabric. The resin is rapidly supplied in plane direction of the fiber along the DM, and then the supplied resin is impregnated in the out-of-plane direction of fiber. It is difficult to predict the flow of resin because the flow of in-plane direction and the out-of-plane direction occur together, and a 3D numerical analysis program is used to simulate the resin infusion process. However, in order to analyze in 3D, many elements are required in the out-of-plane direction of fabric. And the product size is larger, the longer the analysis time needs. Therefore, in this study, a method was suggested to reduce the time required for flow analysis by simplifying the 3D flow analysis to 2D flow analysis. The usefulness was verified by comparing the 3D flow analysis with the simplified 2D flow analysis at the same conditions. The filling time error was about 7% and the reduction of flow analysis time was about 95%. In addition, by utilizing the constant difference in the flow front between the top, middle, and bottom of the fabric of the 3D analysis, the flow front of the top, middle, and bottom of the fabric can be also predicted in the 2D flow analysis.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.49 no.4
• /
• pp.365-373
• /
• 2023

Since the lips are a representative facial part that can express human attraction, aesthetic interest in them has always existed in human history. However, as lips age, they tend to form wrinkles, become thinner, and lose their volume. To counteract this phenomenon, medical procedures such as fillers or fat transplantation have been suggested. In this study, we verified that the one of main effective material complex of L G H&H L IPCERIN^®, combination of cedrol, a sesquiterpene found in cedarwood, and three peptides (acetyl hexapeptide-8, acetyl tetrapeptide-9, and desamidocollagen) could ameliorate the photo-aging and reduce the wrinkles through in vitro experiments. The possibility of improving collagen and elastin expression in skin fibroblasts and reducing MMP expression under photoaging conditions was verified. In addition, it was confirmed that the amount of fat tissue in the lips can be increased by promoting adipose stem cell differentiation and increasing the amount of fat produced in the in vitro adipose stem cell differentiation experiment. Two weeks of human application tests confirmed that a combination of cedrol and peptides can improve the wrinkles, texture, elasticity, and volume of the lips. This study verified that the combination of cedrol and three peptides can be used as effective cosmetic materials to decrease the various signs of aging in the lips.

• Journal of Korea Water Resources Association
• /
• v.57 no.3
• /
• pp.165-179
• /
• 2024

It is crucial to have a comprehensive understanding of inundation and water cycle in urban areas for mitigating flood risks and sustainable water resources management. In this study, we developed a Cellular Automata-based integrated Water cycle model (CAW). A comparative analysis with physics-based and conventional cellular automata-based models was performed in an urban watershed in Portland, USA, to evaluate the adequacy of spatiotemporal inundation simulation in the context of a high-resolution setup. A high similarity was found in the maximum inundation maps by CAW and Weighted Cellular Automata 2 Dimension (WCA2D) model presumably due to the same diffuse wave assumption, showing an average Root-Mean-Square-Error (RMSE) value of 1.3 cm and high scores of binary pattern indices (HR 0.91, FAR 0.02, CSI 0.90). Furthermore, through multiple simulation experiments estimating the effects of land cover and soil conditions on inundation and infiltration, as the impermeability rate increased by 41%, the infiltration decreased by 54% (4.16 mm/m²) while the maximum inundation depth increased by 10% (2.19 mm/m²). It was expected that high-resolution integrated inundation and water cycle analysis considering various land cover and soil conditions in urban areas would be feasible using CAW.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.8
• /
• pp.46-54
• /
• 2016

This study was conducted to investigate the effects of participation in the accelerated rehabilitation with an anti-gravity treadmill program for 16 weeks on isokinetic myofunction and functional score of knee joint, ROM, and VAS score in meniscus repair patients. A total of 10 male adult patients who underwent meniscus repair by the same doctor were investigated in this study. Both extension and flexion peak torque at $60^{\circ}/sec$ and $180^{\circ}/sec$ significantly increased (p<0.001, p<0.01), while under muscle deficit, extension and flexion peak torque at $60^{\circ}/sec$ and extension peak torque at $180^{\circ}/sec$ significantly decreased (p<0.01, p<0.05). ROM in extension significantly decreased (p<0.05), whereas ROM in flexion significantly increased (p<0.01) in response to the program. VAS score significantly decreased (p<0.001) and lysholm scores significantly increased after completion of the program (p<0.001). These results suggest that 16 weeks of the anti-gravity treadmill accelerated rehabilitation program improves isokinetic muscle strength and functional score of knee joint, ROM, and VAS score in meniscus repair patients. Therefore, the anti-gravity treadmill accelerated rehabilitation program, which is a more scientific and effective method than conventional rehabilitation, leads to faster recovery of paly ground and normal daily activities.

• Tuberculosis and Respiratory Diseases
• /
• v.42 no.1
• /
• pp.58-66
• /
• 1995

Background: Acute interstitial pneumonia is a relatively rare form of interstitial pneumonia, since the vast majority of interstitial pneumonia have a more chronic course. It corresponds to the lesion described by Hamman and Rich, as Hamman-Rich disease in 1944. Another name in the clinical literature is accelerated interstitial pneumonia, idiopathic acute respiratory distress syndrome (idiopathic ARDS), and the organizing stage of diffuse alveolar damage. Acute interstitial pneumonia differs from chronic interstitial pneumonia by clinical and pathologic features. Clinically, this disease is characterized by a sudden onset and a rapid course, and reversible disease. Method and Purpose: Five cases of pathologically proven acute interstitial pneumonia were retrospectively studied to define the clinical, radiologic, and pathologic features. Results: 1) The five cases ranged in age from 31 to 77 years old. The onset of illness was acute in all patients, it began with viral-like prodrome 6~40 days prior to shortness of breath, and respiratory failure eventually developed in all patients. In 2 cases, generalized skin rash was accompanied with flu-like symptoms. Etiologic agent could not be identified in any case. 2) All patients had leukocytosis and severe hypoxemia. Pulmonary function test of 3 available cases shows restrictive ventilatory defect, and one survived patient(case 5) has a complete improvement of pulmonary function after dismissal. 3) Diffuse bilateral chest infiltrates were present radiologically. Theses were the ground-glass, consolidation, and reticular densities without honeycomb fibrosis in all patients. The pathologic abnormalities were the presence of increased numbers of macrophages and the formation of hyaline membranes within alveolar spaces. There was also interstitial thickening with edema, proliferation of immature fibroblast, and hyperplasia of type II pneumocyte. In the survived patient(case5), pathologic findings were relatively early stage of acute interstitial pneumonia, such as hyaline membrane with mild interstitial fibrosis. 4) Of the 5 patients, four patients died of respiratory failure 14~90 days after onset of first symptom, and one survived and recovered in symptoms, chest X ray, and pulmonary function test Conclusion: These results emphasize that acute interstitial pneumonia is clinically, radiologically, and pathologically distinct form of interstitial pneumonia and should be separated from the group of chronic interstitial pneumonia. Further studies will be needed to evaluate the pathogenesis and the treatment of acute interstitial pneumonia.

• Economic and Environmental Geology
• /
• v.43 no.3
• /
• pp.235-248
• /
• 2010

To construct the standard methods for evaluation of physicochemical characteristics of tailings in Korea, specific gravity, paste pH, grain size, mineral compositions and heavy metal concentrations of total 26 tailings from 21 metallic mines were analyzed. Specific gravity of tailings ranged from 2.61 to 4.31 (avg. 3.04), and sand and silt grain were dominant in the tailings. Ranges of paste pH were 2.1-9.5 in tailings (7.1-9.2 at magmatic, skarn and hydrothermal replacement deposits and 2.1-9.5 at hydrothermal vein deposits). Additionally, hydrothermal vein deposits could be reclassified into three categories: (1) paste pH>7.0, (2) 4.0

• The korean journal of orthodontics
• /
• v.41 no.5
• /
• pp.312-323
• /
• 2011

Objective: This study compared the bone thickness of the palate between lateral cephalogram and 3D model measurements. Methods: The subjects consisted of 30 adults (15 men,15 women) with a normal skeletal pattern and occlusion. The CT images were transformed to a 3D model, and were compared with the cephalometric image. Descriptive statistics for each variable were calculated. Results: In the 3D CT model, the mid-palatal area was the thickest part. It became thinner as the palate tapered laterally. In the male group, the thinnest portion was positioned 6 mm away from the mid-palate, while in the female group the thinnest portion was 8mm away from the mid-palate. Correlation analysis between the lateral cephalometric and 3D CT model revealed a significant correlation except in the mid palatal area and the area 2 mm lateral to the mid-palate in men, whereas there was a significant relationship in every area in the women. In both men and women, the highest correlation appeared in the area 8 mm lateral to the mid palate. Conclusions: Using regression analysis, an actual prediction of the bone thickness between the measured bone thickness of the lateral cephalometric radiograph and 3D model was made. This will provide useful information for mini-implant length selection when inserting into the palate.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.9
• /
• pp.83-93
• /
• 2016

This study was conducted to develop a 26-week obesity management program and examine the effects of this program on obesity index (body mass index, fat mass percentage, and triglyceride) and psychological variables, self-esteem, dietary self-efficacy, physical activity self-efficacy, and body image among 46 4th-6th obese elementary school children with a BMI above $20kg/m^2$ using a nonequivalent control group quasi-experimental design (experimental group=23, control group=23). This program included a 12-week intensive course (12 times for group education on obesity, exercise, and nutrition, 36 times for practicing diet and physical exercise, and 5 times for psychological counseling) and a 14-week follow-up course (3 times for group education, 3 times for checking diet and physical exercise, and 1 time for psychological counseling. The collected data were analyzed by the Kolmogorov-Smirnov test, chi-squared test, Fisher's exact probability, t-test, and ANCOVA. There were above normal values in body mass index ($20kg/m^2$), fat mass percentage (15-20%), and triglyceride tolerance ($90mg/d{\ell}$) in experimental group and control group. The body mass index (F=94.869, p<.001), fat mass percentage (F=37.361, p<.001), and triglyceride tolerance (F=7.907, p= .007) were significantly lower, while self-esteem (F=19.661, p<.001), dietary self-efficacy (F=16.942, p<.001), physical activity self-efficacy (F=9.363, p= .004), and body image (F=9.782, p= .003) were significantly higher in the experimental group than the control group after 26 weeks. This study provides evidence that the 26-weeks obesity management program is an effective nursing intervention for managing obesity and psychological variables of obese elementary school children.