• Fire Science and Engineering
• /
• v.33 no.2
• /
• pp.30-38
• /
• 2019

Tracking, which is one of the main causes of electrical fires, is perceived as a physical phenomenon of electrical discharge. Hence tracking should be explained based on electric field analysis, conduction path by electron generation, and gas discharge physics. However, few papers have considered these details. This paper proposes a tracking mechanism including their effects on tracking progress. In order to prove this mechanism, a tracking experiment, an electric field analysis for the carbonization evolution model, and an explanation of the tracking process by gas discharge physics were conducted. From the tracking experiment, the current waveforms were measured at each stage of the tracking progress from corona discharge to tracking breakdown. The electric field analysis was carried out in order to determine the electric field on the surface of a dry-band and the high electric field region for electron generation during the generation and progress of carbonization. In this paper, the proposed tracking mechanism consisted of six stages including electron avalanche by corona discharge, accumulation of positive ions, expansion of electron avalanche, secondary electron emission avalanche, streamer, and tracking by conductive path. The pulse current waveforms measured in the tracking experiment can be explained by the proposed tracking mechanism. The results of this study will be used as the technical data to detect tracking phenomenon, which is the cause of electric fire, and to improve the proof tracking index.

• Composites Research
• /
• v.32 no.5
• /
• pp.284-289
• /
• 2019

In the present paper, the dynamic force-moment equilibrium equations, driving power and energy equations are analyzed to formulate the equation for fuel economy(km/liter) equivalent to the driving distance (km) divided by the fuel volume (liter) of the vehicle, a selected model of gasoline powered KIA K3 (1.6v). In addition, the effects of the dynamic parameters such as speed of vehicle (V), vehicle total weight(M), rolling resistance ($C_r$) between tires and road surface, inclined angle of road (${\theta}$), as well as the aerodynamic parameters such as drag coefficient ($C_d$) of vehicle, air density(${\rho}$), cross-sectional area (A) of vehicle, wind speed ($V_w$) have been analyzed. And the possibility of alternative materials such as lightweight metal alloys, fiber reinforced plastic composite materials to replace the conventional steel and casting iron materials and to reduce the weight of the vehicle has been investigated by Ashby's material index method. Through studies, the following results were obtained. The most influencing parameters on the fuel economy at high speed zone (100 km/h) were V, the aerodynamic parameters such as $C_d$, A, ${\rho}$, and $C_r$ and M. While at low speed zone (60 km/h), they are, in magnitude order, dynamic parameters such as V, M, $C_r$ and aerodynamic ones such as $C_d$, A, and ${\rho}$, respectively.

• Journal of Digital Convergence
• /
• v.17 no.4
• /
• pp.219-227
• /
• 2019

This study examined the convergent relationship of stress factors related to the depression level(CES-D) of a college student. The questionnaire was used using an unregistered self-administered questionnaire for 304 students from a college located in J area from Nov. 12, 2018 to Dec. 14, 2018. The hierarchical multiple regression analysis results are as follows: The depression level of respondents turned out to be significantly higher in following groups: a group in which job seeking stress(CMI) is higher, a group in which academic burnout(MBI-SS) is higher, a group in which anxiety(BAI) are higher. The results show explanatory power of 60.7%. The results of the study indicate that the efforts, to decrease job seeking stress, to decrease academic burnout and, to decrease anxiety, are required to decrease the depression level among college students. These results can be utilized in various interventional efforts for academic counseling and guidance, job counseling, and psychological and emotional stability that lowers the depression level in college students. Following studies requires the presentation and analysis of structural models for the structural model that effects the depression levels of college students.

• Journal of Life Science
• /
• v.31 no.8
• /
• pp.736-744
• /
• 2021

Artemisia princeps Pampanini is an herbal medicine widely used to immune function-related diseases, such as anti-oxidative, anti-inflammatory, and antibacterial agents. In this study, we investigated the anti-inflammatory effects of AP extract and underlying mechanisms were evaluated in RAW 264.7 cells. The effects of AP extract were also studied in a complete Freund's adjuvant (CFA)-induced arthritis and lipopolysaccharide (LPS)-induced inflammation mouse model. In RAW 264.7 cells, AP extracts significantly inhibited the LPS-induced nitric oxide (NO) production and inducible NO synthase and cyclooxygenase-2 protein expression. The LPS-induced phosphorylation of mitogen-activated protein kinases and nuclear factor-κB was also significantly blocked by AP extract in RAW 264.7 cells. Oral administration of AP extract suppressed the increase in mouse paw edema and spleen index compared to CFA-treated mice group. Histologically, the infiltration of inflammatory cells was increased in cartilage and synovium in the CFA-treated mouse group, whereas it was suppressed in the AP extract-administered group. Furthermore, AP extract treatment significantly reduced the inflammatory cytokine, tumor necrosis factor-α, levels in CFA and LPS-treated mouse. In conclusion, the anti-inflammatory and anti-arthritis effect of AP extract was confirmed in both in vitro and in vivo models, suggesting that Artemisia princeps Pampanini may be a candidate material for arthritis treatment.

• Smart Structures and Systems
• /
• v.24 no.6
• /
• pp.769-781
• /
• 2019

Dynamic displacement response of civil structures is an important index for in-construction and in-service structural condition assessment. However, accurately measuring the displacement of large-scale civil structures such as high-rise buildings still remains as a challenging task. In order to cope with this problem, a vision-based system with the use of industrial digital camera and image processing has been developed for long-distance, remote, and real-time monitoring of dynamic displacement of supertall structures. Instead of acquiring image signals, the proposed system traces only the coordinates of the target points, therefore enabling real-time monitoring and display of displacement responses in a relatively high sampling rate. This study addresses the in-situ experimental verification of the developed vision-based system on the Canton Tower of 600 m high. To facilitate the verification, a GPS system is used to calibrate/verify the structural displacement responses measured by the vision-based system. Meanwhile, an accelerometer deployed in the vicinity of the target point also provides frequency-domain information for comparison. Special attention has been given on understanding the influence of the surrounding light on the monitoring results. For this purpose, the experimental tests are conducted in daytime and nighttime through placing the vision-based system outside the tower (in a brilliant environment) and inside the tower (in a dark environment), respectively. The results indicate that the displacement response time histories monitored by the vision-based system not only match well with those acquired by the GPS receiver, but also have higher fidelity and are less noise-corrupted. In addition, the low-order modal frequencies of the building identified with use of the data obtained from the vision-based system are all in good agreement with those obtained from the accelerometer, the GPS receiver and an elaborate finite element model. Especially, the vision-based system placed at the bottom of the enclosed elevator shaft offers better monitoring data compared with the system placed outside the tower. Based on a wavelet filtering technique, the displacement response time histories obtained by the vision-based system are easily decomposed into two parts: a quasi-static ingredient primarily resulting from temperature variation and a dynamic component mainly caused by fluctuating wind load.

• Journal of Korean Society of Forest Science
• /
• v.109 no.4
• /
• pp.461-467
• /
• 2020

The aim of this study was to utilize Kozak's stem taper model to develop both a stem taper equation and a stem volume table for Criptomeria japonica, a tree species distributed across Korea. A total of 1,000 sample trees were cut and collected across the country to measure their diameters by stem height. The equation was then used to estimate examine their stem shapes. Our results show that the Fitness Index for the equation was 98.7%, the Mean Absolute Deviation (MAD) was -0.0142, and the MAD was 1.1640, thus indicating a high level of fitness. A statistically significant difference (p < 0.05) was also found from the analysis of discrepancies between a current table and the new table used in this study. It is therefore suggested that the new table-with data from actual stands-will contribute to enhancing the accuracy of national and municipal forest statistics and reducing losses caused by imprecise data on available forest resources.

• Journal of Korean Medicine for Obesity Research
• /
• v.20 no.2
• /
• pp.138-148
• /
• 2020

Objectives: The aim of this study is to evaluate the effects of Bangpungtongseong-san (Fangfengtongsheng-san, BTS) and Daesiho-tang (Dachaihu-tang, DST) on weight loss and improvement in lipid metabolism and glucose metabolism. Furthermore, we intend to develop a prediction model for drug effects through the analysis of the single nucleotide polymorphism (SNP), gut-microbiota, and the expression of immune-related biomarkers. Methods: This study is a single-center, randomized, double-blind, parallel-design clinical trial. One hundred twenty-eight participants will be assigned to the BTS group (n=64) and DST group (n=64). Both groups will be administered 4 g medication three times a day for up to 2 weeks. The primary outcomes is weight loss. The secondary outcomes include bioelectrical impedance analysis, waist circumstance, body mass index, total cholesterol, high-density lipoprotein, triglyceride, insulin resistance. The exploratory outcomes include 3-day dietary recall, food frequency questionnaire, quality of life questionnaire, gut microbiota analysis, immune biomarkers analysis, and SNP analysis. Assessment will be made at baseline and at week 4, 8, and 12. Conclusions: This protocol will be implemented by approval of the Institutional Review Board of Dongguk University. The results of this trial will provide a systematic evidence for the treatment of obesity and enable more precise herbal medicine prescriptions.

• Journal of Digital Convergence
• /
• v.18 no.12
• /
• pp.195-204
• /
• 2020

The purpose of this study is to look for the relationship between export weight and control volume, inland cargo, export cargo transport, ship departure. The analysis period were used for a total of 113 monthly data from January 2011 to May 2020. Data were retrieved from the Korean Statistical Information Service of the Statistics Korea. The data used in this study were performed numerical analysis, index analysis and model analysis using the rate of change from the same month of the previous year. In the trend of the increase rate, the amount of control has plummeted from 150% to 60% due to the influence of Corona 19 in the beginning of 2020. At the same time, export weight and export cargo transport also decreased. As a result of the analysis, export weight showed relatively high synchronization with export cargo transport and control volume. On the other hand, export weight and inland cargo showed relatively low synchronization. Export weight is expected to continue in 2020 after the fluctuation rate began to decrease after 2019. If we can find the point of rebound in control volume or export cargo transport in the future, we can predict the point of increase in export weight. We expect to see an increase in export weight as soon as possible.

• Korean Journal of Food Science and Technology
• /
• v.53 no.3
• /
• pp.313-320
• /
• 2021

The present study aimed to investigate the effect of whole wheat cookie supplemented with Capsosiphon fulvescens (CF) extract on serum glucose homeostasis in C57BL/6 mice. This study examined whether the same effect was demonstrated for whole wheat cookie in comparison to previous research documenting the glucose-lowering effect of food products combined with CF extract. Mice were divided into three groups depending on the diet administered: normal cookie (NC), whole wheat cookie (WC), and WC blended with CF extract (WCFE). After 4 weeks of administering the experimental diet, the blood glucose level, serum insulin level, and homeostatic model assessment for insulin resistance index were found to be significantly lower in the WCFE group than in the NC and WC groups. These results suggest that whole wheat cookie containing CF extract is effective in preventing insulin resistance and maintaining blood glucose homeostasis.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.12
• /
• pp.845-856
• /
• 2020

This study proposes a bridge evaluation system for indivisible permit vehicles such as hydraulic cranes. The permit loads for the bridge evaluation are divided into three categories: routine permit loads, special permit 1 loads, and special permit 2 loads. Routine permit and special permit 1 vehicles are allowed to cross a bridge with normal traffic. For these two permits, the standard lane model in the Korean Highway Bridge Design Code was adopted to consider normal traffic in the same lane. Special permit 2 vehicles are assumed to cross a bridge without other traffic. Structural analyses of two prestressed-beam bridges and two steel box girder bridges were conducted for the proposed permit loads. The rating factors of the four bridges for all permit loads were calculated as sufficiently large values for the moment and shear force so that crossing the bridges can be permitted. A reliability assessment of the bridges was performed to identify the reliability levels for the permit vehicles. It was confirmed that the reliability level of the minimum required strength obtained by the load-resistance factors yields the target reliability index of the design code for the permit vehicles.