• Journal of Life Science
• /
• v.32 no.6
• /
• pp.468-475
• /
• 2022

The functional distinction between stem and progenitor cells is well established in several tissues, particularly in the blood. There, hematopoietic stem cells preserve their self-renewal potential and reconstitution ability in the bone marrow niche. Bone marrow represents a unique setting in which to examine how stroma influences tissue function. It was the setting in which the experimental definition of a niche was first provided in mammalian stem cell biology and where clear evidence for non-cell-autonomous oncogenesis was first defined. The relationship between bone and blood is ancient as all animals since the divergence of fish that have bones and blood, make blood in their bones. This long coevolution engendered complex interrelationships, including the first proposed and first experimentally defined niche for stem cells in mammals. Multiple bone marrow stromal cell types serve as regulators of hematopoiesis, and the dysfunction of some causes myelodysplasia and leukemia. However, no comprehensive atlas of stromal subpopulations exists. Therefore, we think these data point to something of importance, such as how the needs and challenges of the organism become translated down to distinct cell types that critically govern specific functions within tissues and do so at the level of a single molecule. We think this will be of broad interest to those focusing on systems biology and the physiology of organisms, particularly those seeking a molecular basis for understanding cell and tissue behavior. We summarized the current and emerging concepts of hematopoietic stem cells and bone marrow niche.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.34 no.6
• /
• pp.417-426
• /
• 2021

Recently, use of the precast concrete (PC) system, which can increase economy by minimizing field work, has rapidly increased. However, the PC system cannot exhibit structural performance under construction, specifically before integration between members. Furthermore, since it is difficult to secure the structural integrity of beam-column joints even after construction, the PC system is vulnerable to progressive collapse. In the PC system, various types of details for PC beam-column joints have been proposed, while the structural/construction details of PC system generally used in Korea differ from those of overseas PC systems. However, studies on the progressive collapse of the domestic PC system are limited. Thus, in this study, we investigated the structural/construction details of PC beam-column joints mainly used in Korea. Based on the investigation, for the prototype PC system with typical joint details, a nonlinear finite element analysis was carried out to evaluate its structural performance under progressive collapse. Further, a parametric study was performed, and the effect of the design parameters was investigated, to recommend a method to improve the progressive collapse resistance of the PC system.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.2
• /
• pp.43-50
• /
• 2022

Even though the structural safety is confirmed in the design stage, the structural safety is not guaranteed in the construction stage because the structural system is not completed. In addition, since the construction period is shorter than the period of use of the building after completion, it is excessive to apply the same seismic load to the construction stage as in the design stage. ASCE 37-14 presents the concept of seismic load reduction factor during construction, but does not provide a clear application method. Therefore, in this study, the seismic load reduced according to the return period was applied to the example model of a residential middle-rise RC building. The construction stage of the example model was divided into five-story units, and seismic load with the change of the return period was applied to the construction stage models to analyze the change of seismic load during construction and to check the sectional performances of structural members. By comparing the design strength ratio of the shear wall at the design stage and the construction stage, the range of seismic load magnitudes that can assure the safety during construction of a residential middle-rise RC building was analyzed in terms of the return period.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.40 no.3
• /
• pp.207-215
• /
• 2022

This research has been focused on accessing precision and accuracy of UAV (Unmanned Aerial Vehicle)-derived 3-D surveying coordinates. To this end, a highly precise and accurate testing control network had been established by GNSS (Global Navigation Satellite Systems) campaign and its network adjustment. The coordinates of the ground control points and the check points were estimated within 1cm accuracy for 95% of the confidence level. FC330 camera mounted on DJI Phantom 4 repeatedly took aerial photos of an experimental area seven times, and then processed them by two widely used software packages. To evaluate the precision and accuracy of the aerial surveys, 3-D coordinates of the ten check points which automatically extracted by software were compared with GNSS solutions. For the 95% confidence level, the standard deviation of two software's result is within 1cm, 2cm, and 4cm for the north-south, east-west, and height direction, and RMSE (Root Mean Square Error) is within 9cm and 8cm for the horizontal, vertical component, respectively. The interest is that the standard deviation is much smaller than RMSE. The F-ratio test was performed to confirm the statistical difference between the two software processing results. For the standard deviation and RMSE of most positional components, exception of RMSE of the height, the null hypothesis of the one-tailed tests was rejected. It indicates that the result of UAV photogrammetry can be different statistically based on the processing software.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.32 no.5
• /
• pp.175-182
• /
• 2022

Rare-earth elements were doped with Mg to enhance the temperature stability of dielectric properties of BaTiO₃ for its application to MLCC (Multi-Layer Ceramic Capacitor). The additives strongly affect both grain growth and densification behaviors during sintering, and hence dielectric properties. The additive effects therefore should be examined in each system with different additives. This study investigated the crystal structure, grain growth and densification behaviors and related variations in dielectric constant with respect to sintering temperature. Dielectric constant appears to be varied with grain size in a temperature range between 1200 and 1300℃, suggesting the importance of grain size control. The temperature dependence of grain size variation was well explained by an established theory correlating the grain growth behavior with grain boundary structure. This accordance provides a basis for sintering technique to control grain growth thus to improve dielectric constant in rare-earth doped BaTiO₃.

• Journal of Mushroom
• /
• v.20 no.3
• /
• pp.127-137
• /
• 2022

Effects of substrate bed interior environments on mushroom qualities were investigated in oyster mushroom cultivation facilities in which either Reversible Air-Circulation Fans (RACF) blowing air in two directions (upwards and downwards) or customary Convection Fans (CF) with air blowing only upwards were operated throughout the cultivation period. Two days before harvest, the deviation ranges of the bed interior temperature and relative humidity in the facility using RACF were in the ranges of 1.0-1.3℃ and 7.8-9.0% in the first growing cycle, and within 0.7-1.1℃ and 10.0-11.4% in the second cycle. In the facility using CF, the ranges of variation in the indoor environment parameters (5.8-6.4℃ and 21.3-23.1% in the first growing cycle, and 3.4-5.7℃ and 14.6-18.3% in the second growing cycle) were much enlarged compared to those associated with RACF. These results strongly indicate that RACF significantly enhances air uniformity. Some mushroom qualities differed between growing cycles. For instance RACF in the first cycle gave somewhat better qualities than CF, but some qualities, like pileus diameter and stipe length, were slightly lower than those described for CF in the second cycle when the cultivation substrate weakened. The observation that some qualities worsened under RACF conditions, despite better air uniformity during the growing cycle, revealed the possibility that downward wind may exert a non-negligible negative effect on mushroom growth. Therefore in the future, making wind measurements on the interior and exterior of substrate beds is necessary to obtain insights into their influences on mushroom qualities. The RACF operation manual needs to be edited to convey this necessity.

• Korean Journal of Clinical Laboratory Science
• /
• v.53 no.2
• /
• pp.143-150
• /
• 2021

The recent spread of novel and highly variant pathogenic viruses, including the coronavirus (SARS-CoV-2), has increased the demand for diagnostic testing for rapid confirmation. This has resulted in investigating the functional capability of each space, and preparing facility guidelines to secure the safety of medical technologists. During viral evaluations, there is a requirement of negative pressure facilities along with thread separation, during pre-treatment of samples and before nucleic acid amplification. Space composition therefore needs to be planned by considering unidirectional air flow. This classification of safety management facilities is designated as biosafety level 2, and personal protective equipment is placed accordingly. In case of handling dangerous materials, they need to be carried out of the biosafety cabinet, and sterilizers are required for suitable disposal of infectious agents. A common feature of domestic laboratories is maintenance of the sample pre-treatment space at a negative pressure of -2.5 Pa or less, and arranging separate pre-treatment and reagent preparation spaces during the test process. We believe that the data generated in this study is meaningful, and offers an efficient direction and detailed flow for separation of the inspection process and space functions. Moreover, this study introduces construction of the laboratory by applying the safety management standards.

• Journal of the Korean Society of Physical Medicine
• /
• v.16 no.2
• /
• pp.81-90
• /
• 2021

PURPOSE: Aging causes a decrease in muscle mass and a change in posture, which reduces motor function and makes it difficult to perform daily activities independently. As these factors are closely related to the deterioration of the quality of life, it is very important to prevent and manage negative changes in the musculoskeletal system. Forest healing is a nature therapy course that maintains and promotes health using various environmental factors in a forest. The purpose of this study was to identify the effects of the forest healing anti-aging programs on the physical health of the elderly. METHODS: Ten elderly people participated in this study, as part of a forest healing anti-aging program for two days. Functional fitness, muscle strength, gait function, and balance were evaluated before and after the program. RESULTS: The number of arm curls, chair stands, and steps in a 2-min walk significantly increased (p < .05). 8-feet up & go time was significantly decreased (p < .05). Biceps brachii, quadriceps femoris, and calf muscle strength were significantly increased (p < .05). Gait velocity and cadence were significantly increased (p < .05). Step length, stride length, step time, swing time, stance time, and cycle time were significantly decreased (p < .05). Reaching distance in the lateral directions was significantly increased (p < .05). CONCLUSION: The forest healing anti-aging program improves the physical health of the elderly.

• Journal of Korean Society of Forest Science
• /
• v.111 no.2
• /
• pp.251-262
• /
• 2022

We selected a cold-tolerant tea tree (Camellia sinensis L.) through reliable evaluation using a number of cold-tolerance indicators targeting tea tree cultivars such as "Chamnok," "Bohyang," "Sangnok," and "Myungnok" in response to climate change. We conducted a low-temperature damage investigation, "Chamnok" and "Bohyang" were damaged investigated with small amounts of green and bright green. "Sangnok" and "Myungnok" were damaged investigated red and dark red at -10℃. The extent of electrolyte leakage increased as the treatment temperature decreased in all cultivars. We predicted lethal temperatures through non-linear regression analysis, finding relatively higher tolerance to low temperature in "Chamnok" (-9.344℃) and "Bohyang" (- 8.883℃) than that in "Myungnok" (-8.092 ℃) and"Sangnok" (-7.632℃). "Bohyang" showed higher levels of antioxidant activity compared to other cultivars. The lipid peroxidation reaction revealed that "Sangnok" and "Myungnok" had higher MDA content than that of other cultivars when treated at low temperatures. Consequently, predictions of the lethal temperature through non-linear regression analysis of "Chamnok" and "Bohyang" were consistent with their tolerance to low-temperature damage, and antioxidant activity and lipid peroxidation reactions were likewise consistent. The results of this study can be used not only for evaluation and selection of cold-tolerance of tea trees in response to climate change, but also in the cultivation of cold-tolerant plants.

• Journal of Life Science
• /
• v.32 no.5
• /
• pp.375-390
• /
• 2022

Influenza viruses are zoonotic respiratory pathogens, and influenza infections have caused a substantial burden on public health systems and the livestock industry. Although currently approved seasonal influenza vaccines have shown potent protection efficacy against antigenically well-matched strains, there are considerable unmet needs for the efficient control of viral infections. Enormous efforts have been made to develop broadly protective universal influenza vaccines to tackle the huge levels of genetic diversity and variability of influenza viruses. In addition, antiviral drugs have been considered important interventions for the treatment of viral infections. The viral neuraminidase inhibitor oseltamivir is the most widely used antiviral medication to treat influenza A and influenza B viruses. However, unsatisfactory clinical outcomes resulting from side effects and the emergence of resistant variants have led to greater attention being paid to plants as a natural resource for anti-influenza drugs. In particular, the recent COVID-19 pandemic has underpinned the need for safe and effective antiviral drugs with a broad spectrum of antiviral activity to prevent the rapid spread of viruses among humans. This review outlines the results of the antiviral activities of various natural products isolated from plants against influenza viruses. Special focus is paid to the virucidal effects and the immune-enhancing effects of antiviral natural products, since the products have broad applications as inactivating agents for the preparation of inactivated vaccines and vaccine adjuvants.