• Korean Journal of Agricultural Science
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• v.48 no.1
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• pp.163-170
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• 2021

Bacterial infections in the female reproductive tract negatively affect ovarian function, follicular development, and embryo development, leading to the eventual failure of fertilization. Moreover, bacterial lipopolysaccharides (LPS) can interfere with the immune system and reproductive system of the host animal. Therefore, this study examined the effect of LPS on the in vitro maturation (IVM) of pig oocytes. Oocytes were matured in TCM199 medium in the presence of varying concentrations of LPS (0 - 50 ㎍·mL^-1). The maturation rate, cortical granules (CGs) migration, and chromosome alignment were subsequently evaluated during the meiotic development of the oocytes. We observed a dose-dependent and significant decrease in the metaphase II (MII) rate with increasing concentrations of LPS (97.6% control [0 ㎍·mL^-1 LPS] vs. 10.4-74.9% LPS [1 - 50 ㎍·mL^-1], p < 0.05). In addition, compared to the control oocytes without LPS, higher levels of abnormal CGs distribution (18.1 - 50.0% LPS vs. 0% control), chromosome/spindle alignment (20.3 - 56.7% LPS vs. 0% control), and intracellular ROS generation were observed in oocytes matured with LPS (p < 0.05). Nitrite levels were also increased in the maturation medium derived from the oocytes matured with LPS (p < 0.05). These results indicate that LPS induces oxidative stress during IVM and affects oocyte maturation, including CGs migration and chromosome alignment of pig oocytes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.4
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• pp.161-167
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• 2020

In the process of cutting large aircraft parts, the tool may be abnormally worn or damaged due to various factors such as mechanical vibration, disturbances such as chips, and physical properties of the workpiece, which may result in deterioration of the surface quality of the workpiece. Because workpieces used for large aircrafts parts are expensive and require strict processing quality, a maintenance plan is required to minimize the deterioration of the workpiece quality that can be caused by unexpected abnormalities of the tool and take maintenance measures at an earlier stage that does not adversely affect the machining. In this paper, we propose a method to indirectly monitor the tool condition that can affect the machining quality of large aircraft parts through real-time monitoring of the current signal applied to the spindle motor during machining by comparing whether the monitored current shows an abnormal pattern during actual machining by using this as a reference pattern. First, 30 types of tools are used for machining large aircraft parts, and three tools with relatively frequent breakages among these tools were selected as monitoring targets by reflecting the opinions of processing experts in the field. Second, when creating the CNC machining program, the M code, which is a CNC auxiliary function, is inserted at the starting and ending positions of the tool to be monitored using the editing tool, so that monitoring start and end times can be notified. Third, the monitoring program was run with the M code signal notified from the CNC controller by using the DAQ (Data Acquisition) device, and the machine learning algorithms for detecting abnormality of the current signal received in real time could be used to determine whether there was an abnormality. Fourth, through the implementation of the prototype system, the feasibility of the method proposed in this paper was shown and verified through an actual example.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.2
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• pp.169-179
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• 2023

Purpose : Although human periodontal ligament stem cells (hPDLSCs) are a supportive factor for tissue engineering, oxidative stress during cell culture and transplantation has been shown to affect stem cell viability and mortality, leading to failed regeneration. The aim of this study was to evaluate the antioxidant and protective effects against cell damage of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, and the antioxidant signal of hPDLSCs in H₂O₂-induced oxidative stress. Methods : To induce oxidative stress in cultured hPDLSCs, H₂O₂ was used as an exogenous reactive oxygen species (ROS). Dose-dependent celecoxib (.1, 1, 10, or 100 µM) was administered after H₂O₂ treatment. WST-1 assay was used to assess cell damage and western blot was used to observe antioxidant activity of hPDLSCs in oxidative stress. Immunohistochemistry was performed for inverting the localization of the SOD and Nrf2 antibody. Results : We found that progressive cell death was induced in hPDLSCs by H₂O₂ treatment. However, low-dose celecoxib reduced H₂O₂-induced cellular damage and eventually enhanced the SOD activity and Nrf2 signal of hPDLSCs. Oxidative stress-induced morphological change in hPDLSCs included lowered the survival and number of spindle-shaped cells, and shrinkage and shortening of cell fibers. Notably, celecoxib promoted cell survival function and activated antioxidants such as SOD and Nrf2 by positively regulating the cell survival signal pathway, and also reduced the number of morphological changes in hPDLS. Immunohistochemistry results showed a greater number of SOD- and Nrf2-stained cells in the celecoxib-treated group following oxidative stress. Conclusion : By increasing SOD and Nrf2 expression at the antioxidant system, the findings suggest that celecoxib enhanced the antioxidative ability of hPDLSCs and protected cell viability against H₂O₂-induced oxidative stress by increasing SOD and Nrf2 expression in the antioxidant system.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.6
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• pp.47-56
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• 2010

HDD-based RAIDs have been used in high-capacity storage systems for traditional data server. However, their data reliability are relatively low and they consume lots of power since hard disk drive is weak on shock and its power consumption is high due to frequent spindle motor operation. Therefore, this paper presents new SSD based RAID system architecture using various erasure codes. The proposed methode applys Reed-Solomon, EVENODD, and Liberation coding schemes onto file system level and device driver level, respectively. Besides, it uses data allocation method to minimize the side effect of reducing the lifespan of SSD. Detail experimental results show that Liberation code increase wear-leveling rates of SSD based RAID-6 more than other codes. The SSD based RAID system applying erasure codes at the device driver level shows better performance than that at the file system level. I/O performance of RAID-6 system using SSD is 4.5%~8.5% higher than that of using HDD and the power consumption of the RAID system using SSD is 18%~40% less than that of using HDD.

• Toxicological Research
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• v.22 no.4
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• pp.307-313
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• 2006

The development of in vitro assays has been recommended to screening and testing the potential endocrine disruptors (EDs). These assay systems focus only on identifying the estrogenic or antiestrogenic activity of EDs, whereas a few studies have been carried out to screen the thyroid hormone (TH) disruptors. The aim of this study was to evaluate a test system to detect TH disruptors using rat pituitary tumor $GH_3$ cells. The test system is based on the TH-dependent increase in growth rate. As expected, L-3,5,3-triiodothyronine ($(T_3)$ markedly induced a morphological change in $GH_3$ cells from flattened fibroblastic types to rounded or spindle-shaped types. $T_3$ stimulated $GH_3$ cell growth in a dose-dependent manner with the maximum growth-stimulating effect being observed at a concentration $1{\times}10^9M$. In addition, $T_3$ increased the release of growth hormone and prolactin into the medium of the $GH_3$ cells culture. Using this assay system, the TH-disrupting activities of bisphenol A (BPA) and its related compounds were examined. BPA, dimethy/bisphenol A (DMBPA), and TCI-EP significantly enhanced the growth of $GH_3$ cells in the range of $1{\times}10^{-5}M\;to\;1{\times}10^{-6}M$ concentrations. In conclusion, this in vitro assay system might be useful for identifying potential TH disruptors. However, this method will require further evaluation and standardization before it can be used as a broad-based screening tool.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.4
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• pp.279-285
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• 2016

Reliable recording and analysis of peripheral nerve activity is important to recognize the user's intention for controlling a neuro-prosthetic hand. In this paper, we present a peripheral nerve recording system that consisted of an intrafascicular multi-electrode array, an electrode insertion device, and a multi-channel neural amplifier. The 16 channel multi-electrode array was stably implanted into the sciatic nerve of the rat under anesthesia using the electrode insertion device. During passive movements and mechanical stimuli, muscle and cutaneous afferent signals were recorded with the multi-channel neural amplifier. Furthermore, we propose a spike sorting method to isolate individual neuronal unit. The muscle proprioceptive units were classified as muscle spindle afferents or Golgi tendon organ afferents, and the skin exteroceptive units were categorized as slow adapting afferents or fast adapting afferents. Experimental results showed that the proposed method could be applicable to record and analyze peripheral nerve activity in neuro-prosthetic systems.

• International Journal of Ocean System Engineering
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• v.2 no.4
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• pp.209-213
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• 2012

Recently, the fuel using in the diesel engines of marine ships has been changed to a low quality of heavy oil because of the steady increase in the price of oil. Therefore, the wear and corrosion in all parts of the engine such as the cylinder liner, piston crown, and spindle and seat ring of exhaust valves has correspondingly increased. The repair welding of a piston crown is a unique method for prolonging its lifetime from an economic point of view. In this case, filler metals with a high corrosion and wear resistance are mainly being used for repair welding. However, often at a job site on a ship, a piston crown is actually welded with mild filler metals. Therefore, in this study, mild filler metals such as CSF350H, E8000B2, and 435 were welded to SS401 steel as the base metal, and the corrosion properties of the weld metals with and without post weld heat treatment were investigated using some electrochemical methods in a 0.1% $H_2SO_4$ solution. The weld metal welded with CSF350H filler metal exhibited the best corrosion resistance among these filler metals, irrespective of the heat treatment. However, the weld metal zones of the E8000B2 and 435 filler metals exhibited better and worse corrosion resistance with the heat treatment, respectively. As a result, it is suggested that in the case of repair welding with CSF350H and 435 filler metals, no heat treatment is advisable, while heat treatment is desirable if E8000B2filler metal is used with repair welding.

• Journal of the Korea Society of Computer and Information
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• v.16 no.10
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• pp.23-31
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• 2011

Recently, Solid state disk is mainly used because this device has lower power consumption as well as higher response time. But it features higher price and lower performance at delete and write operations compared with HDD. To compensate this defect, Hybrid hard disk with internal non-volatile flash memory was issued. This NVCache is used as a kind of cache for disk blocks. In this paper, an I/O scheme for H-HDD is proposed for improving low power consumption as well as response time. Our method is to use this NVCache as read cache mainly and write cache when write requests are concentrated. In read cache operation, disk blocks with higher priority determined on basis of time as well as spatial localities are prefetched, which can improve response time. The write operation is conducted only at write peak time as disk spindle up costs higher battery power as well as response time. Experiments results show that the suggested method can improve response time of H-HDD and lower the power consumption.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2159-2166
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• 2000

Recently, high performance machining center requires special type of sealing mechanism that prevent a leakage of oil jet or oil mist lubrication system. Sealing of oil-air mixture plays important r oles to have an enhanced lubrication for performance machining center. Current work emphasizes on investigations of the air jet effect on the protective collar type labyrinth seal. To improve sealing capabilities of conventional labyrinth seals, air jet is injected against the leakage flow. In this study, an adapted model is introduced to improve sealing capability of conventional non-contact type seals. It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. The sealing effects of the leakage clearance and the air jet magnitude aic studied in various parameters. Gas or liquid has been used as a working fluid for most of nori-contact types seals including the labyrinth seal. However, it is more reasonable to regard two-phase flows because oil mist or oil jet are used for high performance spindle's lubrication. In this study, working fluid is regarded as two phases that are mixed flow of oil and air phase. Both of turbulence and compressible flow model are also introduced in a CFD analysis to represent an isentropic process. Estimation of non-leaking property is determined by amount of pressure drop in the leakage path. Results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effect of the sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger

• Journal of Korea Multimedia Society
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• v.5 no.2
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• pp.215-221
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• 2002

In high speed optical disc devices, the vibration caused by unbalanced displacement leads the focus and tracking servo systems to be unstable, and increases the data search time. In this paper, we propose a new scheme to solve the unbalanced displacement problem. The proposed method detects the unbalanced rate by differential amplifying optical power received at photo diode and converts it into an electrical signal. controlling the speed of spindle motor, according to the detected unbalanced rate, makes it possible to improve the performance of tracking and data searching tasks. Also, we analyze the dynamic characteristics of focus and tracking servo systems in high speed mode and provide the firmware and hardware architecture that the proposed method can be installed as an add-on- module in the existing system.