• Biomolecules & Therapeutics
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• v.27 no.1
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• pp.41-47
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• 2019

The apoptotic effects of shikonin (5,8-dihydroxy-2-[(1R)-1-hydroxy-4-methylpent-3-enyl]naphthalene-1,4-dione) on the human colon cancer cell line SNU-407 were investigated in this study. Shikonin showed dose-dependent cytotoxic activity against SNU-407 cells, with an estimated $IC_{50}$ value of $3{\mu}M$ after 48 h of treatment. Shikonin induced apoptosis, as evidenced by apoptotic body formation, sub-G_1$ phase cells, and DNA fragmentation. Shikonin induced apoptotic cell death by activating mitogen-activated protein kinase family members, and the apoptotic process was mediated by the activation of endoplasmic reticulum (ER) stress, leading to activation of the $PERK/elF2{\alpha}/CHOP$ apoptotic pathway, and mitochondrial $Ca^{2+}$ accumulation. Shikonin increased mitochondrial membrane depolarization and altered the levels of apoptosis-related proteins, with a decrease in B cell lymphoma (Bcl)-2 and an increase in Bcl-2-associated X protein, and subsequently, increased expression of cleaved forms of caspase-9 and -3. Taken together, we suggest that these mechanisms, including MAPK signaling and the ER- and mitochondria-mediated pathways, may underlie shikonin-induced apoptosis related to its anticancer effect.

• Steel and Composite Structures
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• v.48 no.2
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• pp.131-143
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• 2023

The CFRP bar was used to achieve more ductile and durable headed-stud shear connectors in composite components. Three series of push-out tests were firstly conducted, including specimens reinforced with pure steel fibers, steel and CFRP bars. The distributed stress was measured by the commercial PPP-BOTDA (Pre-Pump-Pulse Brillouin optical time domain analysis) optical fiber sensor with high spatial resolution. A series of numerical analyses using non-linear FE models were also made to study the shear force transfer mechanism and crack response based on the test results. Test results show that the CFRP bar increases the shear strength and stiffness of the large diameter headed-stud shear connection, and it has equivalent reinforcing effects on the stud shear capacity as the commonly used steel bar. The embedded CFRP bar can also largely improve the shear force transfer mechanism and decrease the tensile stress in the transverse direction. The parametric study shows that low content steel fibers could delay the crack initiation of slab around the large diameter stud, and the CFRP bar with normal elastic modulus and the standard reinforcement ratio has good resistance to splitting crack growth in headed stud shear connectors.

• Current Optics and Photonics
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• v.8 no.4
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• pp.382-390
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• 2024

Laser propagation through atmospheric disturbances is vital for applications such as laser optical communication, satellite laser ranging (SLR), laser guide stars (LGS) for adaptive optics (AO), and laser energy transmission systems. Beam degradation, including energy loss and pointing errors caused by atmospheric turbulence, requires thorough numerical analysis. This paper investigates the impact of laser beam parameters on ground-to-space laser propagation up to an altitude of 100 km using vertical atmospheric disturbance profiles from the Geochang SLR Observatory in South Korea. The analysis is confined to 100 km since sodium LGS forms at this altitude, and beyond this point, beam propagation can be considered free space due to the absence of optical disturbances. Focusing on a 100-watt class laser, this study examines parameters such as laser wavelengths, beam size (diameter), beam jitter, and beam quality (M²). Findings reveal that jitter, with an influence exceeding 70%, is the most critical parameter for long-exposure radius and pointing error. Conversely, M², with an influence over 45%, is most significant for short-exposure radius and scintillation.

• Composites Research
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• v.31 no.3
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• pp.83-87
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• 2018

An object in the Low Earth Orbit (LEO) is affected by many environmental conditions unlike earth's surface such as, Atomic oxygen (AO), Ultraviolet Radiation (UV), thermal cycling, High Vacuum and Micrometeoroids and Orbital Debris (MMOD) impacts. The effect of all these parameters have to be carefully considered when designing a space structure, as it could be very critical for a space mission. Polybenzimidazole (PBI) is a high performance thermoplastic polymer that could be a suitable material for space missions because of its excellent resistance to these environmental factors. A thin coating of PBI polymer on the carbon epoxy composite laminate (referred as CFRP) was found to improve the energy absorption capability of the laminate in event of a hypervelocity impact. However, the overall efficiency of the shield also depends on other factors like placement and orientation of the laminates, standoff distances and the number of shielding layers. This paper studies the effectiveness of using a PBI coating on the front bumper in a multi-shock shield design for enhanced hypervelocity impact resistance. A thin PBI coating of 43 micron was observed to improve the shielding efficiency of the CFRP laminate by 22.06% when exposed to LEO environment conditions in a simulation chamber. To study the effectiveness of PBI coating in a hypervelocity impact situation, experiments were conducted on the CFRP and the PBI coated CFRP laminates with projectile velocities between 2.2 to 3.2 km/s. It was observed that the mass loss of the CFRP laminates decreased 7% when coated by a thin layer of PBI. However, the study of mass loss and damage area on a witness plate showed CFRP case to have better shielding efficiency than PBI coated CFRP laminate case. Therefore, it is recommended that PBI coating on the front bumper is not so effective in improving the overall hypervelocity impact resistance of the space structure.

• International journal of advanced smart convergence
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• v.12 no.3
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• pp.1-12
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• 2023

A public address (PA) system installed in a building is a system that delivers alerts, announcements, instructions, etc. in an emergency or disaster situation. As for the products used in PA systems, with the development of information and communication technology, PA products with various functions have been introduced to the market. PA systems recently launched in the market may be connected through a single network to enable efficient management and operation, or use voice recognition technology to deliver quick information in case of an emergency. In addition, a system capable of locating a user inside a building using a location-based service and guiding or responding to a safe area in the event of an emergency is being launched on the market. However, the new PA systems currently on the market add some functions to the existing PA system configuration to make system operation more convenient, but they do not change the complex PA system configuration to reduce facility costs, maintenance, and management costs. In this paper, we propose a novel PA system configuration for buildings using audio networks and control hierarchy over peer-to-peer (Anchor) technology based on audio over IP (AoIP), which simplifies the complex PA system configuration and enables convenient operation and management. As a result of the study, through the emergency signal processing algorithm, fire broadcasting was made possible according to the detection of the existence of a fire signal in the Anchor system. In addition, the control device of the PA system was replaced with software to reduce the equipment installation cost, and the PA system configuration was simplified. In the future, it is expected that the PA system using Anchor technology will become the standard for PA facilities.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.2
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• pp.1-13
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• 2001

Beginning in the Wei-Chin and Liu Ch´ao era(AD. 220-589), an awareness of natural beauty emerged as the major interest of scholars which created such a social atmosphere that served as the foundation of prosperous Chinese art. During the T´ang period, the desire to achieve natural beauty began to dominate every field of art including gardening. This study covers the T´ang period when scholars began to be conscious of aesthetics. The main objective of this study is to examine the significance of natural beauty as interpreted by Wangwei, an artist representative of the period, and of Wangchuan Villa in relation to aspects of garden theory. This study is mainly based on Wangwei´s anthology, landscape painting describing Wangchuan Villa, and historical records related to the Villa. The summary of conclusions of this study is as follows: 1) Wangwei´s concept of natural beauty is a combination of objective natural beauty and pastoral beauty, which stresses the essential beauty of nature. Moreover, he considered nature as a religious Utopia. 2)Wangchuan Villa, where Wangwei stayed until his death, was a place of seclusion representing his idea of natural beauty. There, he was able to realize the paradise of Buddhism full of zen aspirations. 3)From the perspective of garden theory, Wangchuan Villa can be classified as a suburb villa in terms of location, as a landscape garden in terms of elements, and as a villa based on a typical private land system in terms of forms. In addition, it may be considered as a garden that laid the foundation to realize a field of non-visible image and non-visible landscape, which is fundamental element of scholarly garden design.

• Yonsei Medical Journal
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• v.59 no.9
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• pp.1064-1071
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• 2018

Purpose: To explore the influence of S100 calcium binding protein A4 (S100A4) knockout (KO) on methionine-choline-deficient (MCD) diet-induced non-alcoholic fatty liver disease (NAFLD) in mice. Materials and Methods: S100A4 KO mice (n=20) and their wild-type (WT) counterparts (n=20) were randomly divided into KO/MCD, Ko/methionine-choline-sufficient (MCS), WT/MCD, and WT/MCS groups. After 8 weeks of feeding, blood lipid and liver function-related indexes were measured. HE, Oil Red O, and Masson stainings were used to observe the changes of liver histopathology. Additionally, expressions of S100A4 and proinflammatory and profibrogenic cytokines were detected by qRT-PCR and Western blot, while hepatocyte apoptosis was revealed by TUNEL staining. Results: Serum levels of aminotransferase, aspartate aminotransferase, triglyceride, and total cholesterol in mice were increased after 8-week MCD feeding, and hepatocytes performed varying balloon-like changes with increased inflammatory cell infiltration and collagen fibers; however, these effects were improved in mice of KO/MCD group. Meanwhile, total NAFLD activity scores and fibrosis were lower compared to WT+MCD group. Compared to WT/MCS group, S100A4 expression in liver tissue of WT/MCD group was enhanced. The expression of proinflammatory ($TGF-{\alpha}$, $IL-1{\beta}$, IL-6) and profibrogenic cytokines ($TGF-{\beta}1$, COL1A1, ${\alpha}-SMA$) in MCD-induced NAFLD mice were increased, as well as apoptotic index (AI). For MCD group, the expressions of proinflammatory and profibrogenic cytokines and AI in KO mice were lower than those of WT mice. Conclusion: S100A4 was detected to be upregulated in NAFLD, while S100A4 KO alleviated liver fibrosis and inflammation, in addition to inhibiting hepatocyte apoptosis.

• Journal of Chest Surgery
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• v.20 no.1
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• pp.1-12
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• 1987

Respiratory care with oxygen inhalation is often a necessity to maintain life, and it is one of the important therapeutic adjuncts in respiratory disease and in intensive care after surgery. However, it has been reported that oxygen toxicity occurs after prolonged exposure to 100% 0, [Smith, 1899; Kistler et al. 1967; Schaffner et al. 1967; Rowland and Newman, 1969. Subjective symptoms of oxygen toxicity include tracheal irritation, frequent cough, some burning sensation in the trachea, tachypnea, severe dyspnea, etc. [Welch, 1963; Fisher et al, 1968; Milier et al, 1970; Clark and Lambertsen, 1971; Sackner, 1975]. Pathologic findings are atelectasis, injuries to the pulmonary capillaries and hemorrhage in the alveoli in gross specimens. There can be inflammation, proliferation of fibrin, thickening of alveolar membranes, degeneration of collagen fibers and interstitial edema in the microscopic findings. [Penrod, 1956; Cedergren, 1959; Bean, 1965; Schaffner, 1967]. Dubois and colleagues [1961] found that the amount of pulmonary surfactant was decreased in oxygen toxicity and atelectasis followed by the decreased pulmonary surfactant. Many authors reported that vital capacity, inspiratory force, pulmonary compliance, pulmonary capillary blood flow and pulmonary elasticity were deceased and arteriovenous shunting increased. [Comroe et al, 1945; Fuson et al, 1965; Kistler et al, 1966; Knowles and Blenner-hassett, 1967; Barber et al, 1978]. Many human volunteers were examined after prolonged exposure in a high oxygenated chamber and there were a few reports on animals with oxygen toxicity, subjects including rabbits. Gas partial pressures of alveoli and arteries were measured in rabbits exposed to 100% $O_2$ and the alveolar-arterial gas gradients were analyzed, which is the basis for the study of oxygen toxicity. These rabbits were divided into two groups; rabbits under natural respiration, and second group under artificial respiration with a respirator. The alveolar $PO_2$ [$P]AO_2$] and $PCO_2$ [$PACO_2$], and the arterial $PO_2$ [$PaO_2$] were measured under varying $O_2$ pressures; 15% $O_2$, 21% $O_2$ and 100% $O_2$.

• Journal of Korean Foot and Ankle Society
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• v.12 no.1
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• pp.80-85
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• 2008

Purpose: To evaluate and compare the outcome between interlocking IM nailing and LCP fixation in the treatment of distal metaphyseal tibial fracture. Materials and Methods: From January 2000 to December 2007, 17 patient were treated by interlocking IM nail and 13 patient were treated by LCP fixation for distal metaphyseal tibial fracture. Results: According to AO classification, there were 2 type A1 fracture (12%), 6 type A2 fracture (36%), 3 type A3 fracture (18%), 4 type B1 fracture (24%), 1 type B3 fracture (6%), 1 type C1 fracture (6%) in interlocking IM nailing group and 1 type A2 fracture (7.7%), 2 type A3 fracture (15.4%), 3 type B1 fracture (23%), 3 type B2 fracture (23%), 3 type C1 fracture (23%), 1 type C2 fracture (7.7%) in LCP fixation group. The clinical functional outcome (according to AOFAS score) is 75.6 point in IM nailing group and 81.5 point in LCP fixation group. In IM nailing group, 65% of patient showed satisfactory result and In LCP fixation group, 77% of patient showed satisfactory result. Conclusion: There is no difference on clinical results between IM nailing and MIPPO (minimal invasive percutaneous plate osteosynthesis) group in the treatment of distal tibia fracture. But MIPPO group have higher subjective satisfactory score and less complication rate. The weakness of our study is a small case number and limited follow-up and we believe a better designed prospective study will be needed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.8
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• pp.672-678
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• 2013

In the recent year, along with the rapid development of LED technology, many applications using LEDs have been researched and indoor positioning is one of them. In particular, previous indoor positioning systems based on visible light communication combine triangulation manner such as AoA, ToA TDoA. But most of them needs transmitting unique ID of each LED panel. In this paper, we propose an non LED-ID based indoor positioning system in which the visible light radiated from LEDs is used to locate the position of receiver. Compared to current indoor positioning systems using LED light, our system has the advantages of simple implementation, low cost and high accuracy. Through the computer simulation, our system can achieve a high estimation accuracy of 3.6cm in average in the $5{\times}5{\times}3m^3$ room.