• Journal of Korean Society of Steel Construction
• /
• v.9 no.3 s.32
• /
• pp.341-350
• /
• 1997

The objective of this study is to investigate the structural behavior of the composite slabs with the new metal deckplate. The new deckplate can be used as structural member with topping concrete. So several experiments of this structural test and the fire resistance test were done. From this experiments. slabs with new metal deckpklate were verified as composite slabs. In this paper, this verifications were compared with the international design methods. For experiment. 49 specimens were made. the main parameters are deckplate thickness (1.2mm. 1.6mm) depth of topping concrete(85mm. 90mm). support condition(simple, 2-span), shear reinforcment(studs), span(2.7m, 3.0m, 3.3m. 3.6m. 3.9m) and shear span(L/3, L/4, L/7). We analyzed the structural behavior of composite slab throughout the moment-curvature relationship which is obtained with the program using the computer language. Turbo C. From this development for slab system, the reinforced concrete or steel structure building may be easy, economical for construction, And informations about the structural behavior of composite slabs will be utilized to established korea standard.

• Journal of Distribution Science
• /
• v.13 no.5
• /
• pp.53-60
• /
• 2015

Purpose - The purpose of this paper is to shed light on the importance of the slope and curvature of the volatility curve implied in option prices in the KOSPI 200 options index. A number of studies examine the implied volatility curve, however, these usually focus on cross-sectional characteristics such as the volatility smile. Contrary to previous studies, we focus on time-series characteristics; we investigate correlation dynamics among slope, curvature, and level of the implied volatility curve to capture market information embodied therein. Our study may provide useful implications for investors to utilize current market expectations in managing portfolios dynamically and efficiently. Research design, data, and methodology - For our empirical purpose, we gathered daily KOSPI200 index option prices executed at 2:50 pm in the Korean Exchange distribution market during the period of January 2, 2004 and January 31, 2012. In order to measure slope and curvature of the volatility curve, we use approximated delta distance; the slope is defined as the difference of implied volatilities between 15 delta call options and 15 delta put options; the curvature is defined as the difference between out-of-the-money (OTM) options and at-the-money (ATM) options. We use generalized method of moments (GMM) and the seemingly unrelated regression (SUR) method to verify correlations among level, slope, and curvature of the implied volatility curve with statistical support. Results - We find that slope as well as curvature is positively correlated with volatility level, implying that put option prices increase in a downward market. Further, we find that curvature and slope are positively correlated; however, the relation is weakened at deep moneyness. The results lead us to examine whether slope decreases monotonically as the delta increases, and it is verified with statistical significance that the deeper the moneyness, the lower the slope. It enables us to infer that when volatility surges above a certain level due to any tail risk, investors would rather take long positions in OTM call options, expecting market recovery in the near future. Conclusions - Our results are the evidence of the investor's increasing hedging demand for put options when downside market risks are expected. Adding to this, the slope and curvature of the volatility curve may provide important information regarding the timing of market recovery from a nosedive. For financial product distributors, using the dynamic relation among the three key indicators of the implied volatility curve might be helpful in enhancing profit and gaining trust and loyalty. However, it should be noted that our implications are limited since we do not provide rigorous evidence for the predictability power of volatility curves. Meaning, we need to verify whether the slope and curvature of the volatility curve have statistical significance in predicting the market trough. As one of the verifications, for instance, the performance of trading strategy based on information of slope and curvature could be tested. We reserve this for the future research.

• Journal of Astronomy and Space Sciences
• /
• v.21 no.2
• /
• pp.153-166
• /
• 2004

Interplanetary trajectories using the gravity assists are studied for future Korean interplanetary missions. Verifications of the developed softwares and results were performed by comparing data from ESA's Mars Express mission and previous results. Among the Jupiter exploration mission scenarios, multi-planet gravity assist mission to Jupiter (Earth-Mars-Earth-Jupiter Gravity Assist, EMEJGA trajectory) requires minimum launch energy ($C_3$) of 29.231 $Km^2$/$S^2$ with 4.6 years flight times. Others, such as direct mission and single-planet(Mars) gravity assist mission, requires launch energy ($C_3$) of 75.656 $Km^2$/$S^2$ with 2.98 years flight times and 63.590 $Km^2$/$S^2$ with 2.33 years flight times, respectively. These results show that the planetary gravity assists can reduce launch energy, while EMEJGA trajectory requires the longer flight time than the other missions.

• Membrane Journal
• /
• v.30 no.3
• /
• pp.181-189
• /
• 2020

In the present study, a biomimetic alumina membrane was fabricated by using selenic acid as an electrolyte to overcome the asymmetry limit of the square pulse anodization process. The prepared membrane has conical channels with a minimum diameter of 10 nm, a maximum diameter of 50 nm, and a length of 5 ㎛. The rectification property was higher than membranes fabricated by sulfuric acid. It showed 2.9 times larger current at +1 V than -1 V. Also, the membrane, which sulfonic acid group was introduced by surface modification, showed 4.2 times larger rectification property at -1 V than +1 V. Theoretical verifications were supported by the numerical analyses of 2D models. The results of the present study present a convenient method to fabricate two type membranes with different rectification properties and are expected to be used to control ion transport.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.1
• /
• pp.40-47
• /
• 2018

Porous walkway blocks are constructed for the purpose already, but reserved water is easily consumed due to the bigger permeability than necessary. Furthermore, porous structure reduces the strength of blocks, which resulting cracking and settlements in walkways. In this study, we suggested a solution for given problems by determination for the location of minimum principal stress in walkway blocks against moving foot loads in order to design and verifying the determined location of minimum principal stress. An optimum design with a verification example for determined location of minimum principal stress have been presented in a two dimensional Block member on elastic foundation for pedestrian walkway for reserving water inside. The minimum value for sum of shear forces is found when ${\times}1$ is 58.58 mm(30% of total span, 200mm), while the minimum deformation is located at ${\times}2=80mm$(70% of total span, 200 mm). In a modified model, When moving boundary condition(walkway foot loads) is located at ${\times}1$(=0 mm), the location of minimum principal stresses is found at 168 mm( 84% of span, 200 mm), in which the stress concentration due to the foot load is modeled as two layers of distributed loads(reactions of foundation modeled as springs). Consequently, zero deformed reservoirs for rainwater on the neutral axis (${\times}2=167mm$) has been determined in the modified model with three dimensional FEM analysis verifications.

• Ecology and Resilient Infrastructure
• /
• v.6 no.4
• /
• pp.250-257
• /
• 2019

Recently, 357 water-friendly space were established near the main streams of the country through the Four Major Rivers Project, which was used as a resting and leisure space for the citizens, and the river environment and ecological health were improved. We are working hard to reduce the number of points and plan and manage the water-friendly space. In particular, attempts are being made to utilize mobile big data to make more scientific and systematic research on the number of users. However, when using mobile big data compared to the existing method of conducting field surveys, it is possible to easily identify spatial user movement patterns, but it is different from the actual amount of use, so various verifications are required to solve this problem. Therefore, this study evaluated the accuracy of estimating the number of users using mobile big data by comparing the number of visitors using mobile big data and the number of visitors using drone for Samrak ecological park located in the mouth of Nakdong River. As a result, in the river hydrophilic district, it was difficult to accurately estimating the usage pattern of each facility due to the low precision of pCELL, and it was confirmed that the usage patterns in the park could be distorted due to the signals stopped at roads and parking lots. Therefore, it is necessary to improve the number of pCELLs in the water-friendly space and to estimate the number of visitors excluding facilities such as roads and parking lots in future mobile big data processing.

• Fire Science and Engineering
• /
• v.32 no.5
• /
• pp.112-121
• /
• 2018

In the present study, a group of subjects consisting of "Fire Professional Engineers" was selected to examine the effects of life safety awareness and safety behaviors of the subjects on life safety through an analyses of the descriptive statistics, factors, reliability, and correlation; simple regression and three-stage regression analyses on mediation were also carried out based on the hypotheses developed. The results showed that the degree of safety behavior increased by 72.1% in accordance with the increased safety awareness of fire professional engineers; the life safety was also increased by 61.5% and 64.5% by the increases in safety awareness and safety behavior of fire professional engineers, respectively. In addition, the safety behaviors demonstrated a partial mediatory effect in the relationship between safety awareness and life safety. All hypotheses (H1, H2, H3, H4), established for the present study, were accepted based on statistical verifications that justified an amendment of the Acts pertinent to firefighting service focusing on life safety; the data are expected to be exploited to reflect significance of life safety.

• Journal of the Korean association of regional geographers
• /
• v.21 no.2
• /
• pp.379-393
• /
• 2015

The fire damage has been increased as the frequency of fire incidence decreases with increasing in death and economic loss. Local governments are dependent on the activities of fire-fighters with crude preparedness and prevention for fire incidence. Most of researches on fire safety have focused on descriptive statistics which show general trends in fire incidence and condition. Here we tried to make a mutual causal model for fire damage, to make three big hypotheses with laying three small hypotheses under each big hypothesis. Five years statistics from public domains in the form of hardcopy or softcopy were collected and fifteen independent variables were selected to explain the number of death, the number of fire incidence and the amount of economic loss from fire incidence. The significances of statistics are different among the regional characteristics. The hypotheses were partially rejected and the meanings of rejected factors will refresh the tentative prejudice. It is necessary to revise the principle that the number of population and size of area are regarded as the most important criteria to allocate resources for fire control and to have the criteria flexible with results of our research such as the number of the weak to fire disaster.

• Journal of dental hygiene science
• /
• v.6 no.2
• /
• pp.119-125
• /
• 2006

This study executed questionnaire by own recording way using questionnaire to Dental Hygiene of W health science college and 365 students locating in Cholla-bukdo area from September 10, 2005 October 9. Distribution by class was first-year student 115 people, second-year student 125 people, third-year student 120 people, and collected data enforced crossing analysis, multiple response analysis, correlation analysis using statistical analysis program SPSS(V. 11.5) and significance level(${\alpha}$) used in all verifications was 0.05. 1. Seoul was the most to employment hope area and(p<0.01), there was difference that keep in mind statistically because appears salary highest about selection reason(p<0.001). 2. knowledge degree about can go to work appeared by 52.8% for doing not know, and when go to work 60.8% was thinking aptitude and interest most importantly and there was difference that keep in mind statistically(p<0.01). 3. when go to work 35.3% prevention medical examination and treatment business that 27.2% hopes dental management business appear(p<0.01). 4. I appeared accomplish result weak static correlation that analyze interrelation of degree of dictionary knowledge about can do interest degree about dental hygienist job and an employment(p<0.01).

• Geophysics and Geophysical Exploration
• /
• v.5 no.4
• /
• pp.236-249
• /
• 2002

We have extended the three-dimensional (3-D) resistivity imaging algorithm to cover the 3-D resistivity tomography problem, where resistivity data are acquired using electrodes installed in several boreholes as well as at the earth surface. The imaging algorithm consists of the 3-D finite element forward modeling and least-squares inversion scheme, where the ACB (Active Constraint Balancing) is adopted to enhance the resolving power of the inversion. Sensitivity analysis with numerical verifications shows that 3-D resistivity tomography is a very appealing method and can be used to get 3-D attitude of subsurface structures with very high-resolution. Moreover, we could accurately handle the topography effect, which could cause artifacts in the resistivity tomography. In the application of 3-D resistivity tomography to the real field data set acquired at the quarry mine, we could derive a very reasonable and accurate image of the subsurface.