• Fire Science and Engineering
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• v.26 no.5
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• pp.48-53
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• 2012

The autoignition temperature (AIT) is important index for the safe handling of flammable liquids which constitute the solvent mixtures. This study measured the AITs and ignition delay time for n-Butanol+sec-Butanol system by using ASTM E659 apparatus. The AITs of n-Butanol and sec-Butanol which constituted binary system were $340^{\circ}C$ and $447^{\circ}C$, respectively. The experimental AITs of n-Butanol+sec-Butanol system were a good agreement with the calculated AITs by the proposed equations with a few A.A.D. (average absolute deviation).

• Fire Science and Engineering
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• v.27 no.1
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• pp.8-13
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• 2013

The autoignition temperature (AIT) is important index for the safe handling of flammable liquids which constitute the solvent mixtures. This study measured the AITs and ignition delay time for Benzene and n-Hexane system by using ASTM E659 apparatus. The AITs of Benzene and n-Hexane which constituted binary system were $583^{\circ}C$ and $240^{\circ}C$, respectively. The experimental AITs of Benzene and n-Hexane system were a good agreement with the calculated AITs by the proposed equations with a few A.A.D. (average absolute deviation).

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.20 no.3
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• pp.152-157
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• 2009

Objectives : We investigated the parenting stress and depressive mood of mothers with developmentally-delayed children and the effects of participation in a mother-child development promotion program on same. Methods : Subjects were the mothers of 20 developmentally-delayed children. The severity of the mothers' parenting stress was evaluated via the Korean version of the Parenting Stress Index, Short Form (K-PSI-SF) and the severity of their depressive symptoms were evalueted by the Korean version of the Beck Depression Inventory (K-BDI). Results : The mean K-PSI-SF score and mean K-BDI score for these mothers were 93.35 (SD=10.47) and 23.25 (SD=10.42), respectively. These scores correspond to high parenting stress and moderate depression. The mothers who participated in a mother-child attachment- promotion program showed significant decreases in their K-PSI-SF and KBDI scores. Conclusion : Our data suggest that a mother-child attachment promotion program with emphasis on child development is effective in reducing parenting stress and depressive mood in mothers of developmentally-delayed children.

• Journal of Navigation and Port Research
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• v.33 no.10
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• pp.665-669
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• 2009

When maneuvering a ship in a narrow channel or under bridge, the ship operator may take actions of slowdown engine and altering course in order to avoid possible navigational dangers, which may reduce difficulties on navigation or collsion avoidance against other ship and/or bridge. In this paper, taking notice of the stress caused by these actions of slowdown engine and altering course, survey is carried out for whether it is possible to quantify the stress by time delay as an index. Based on the ship handling simulator experiment, it is verified that difficulty of navigation changes is highly correlated with the time delay, which result from compensation actions of slowdown engine and altering course.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06c
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• pp.46-48
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• 2006

This paper addresses the problem of monitoring continuous k-nearest neighbor (k-NN) queries. Given a set of moving (or static) objects and a set of moving (or static) query points, monitoring continuous k-NN query retrieves and updates the closest k objects to a query point continually. In order to support location based services (LBSs) in highly dynamic environments, where objects and/or queries are frequently moving, monitoring continuous queries require real-time updated results when objects and/or queries change their locations. Thus, it is important to minimize time delay for maintaining up to date the results. In this paper, we present monitoring method to shorten time delay for updating continuous k-NN queries based on the notion of result region and the minimum bounding rectangle enclosing all objects in each cell, referred to as c-MBR, in the grid index structure. Simulations are conducted to show the efficiency of the proposed method.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10a
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• pp.147-158
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• 2001

In general, two methods have been used to predict settlement of soft ground. One method is Terzaghi's one dimensional consolidation theory which gives time-settlement relationship using the standard consolidation test results. The other is forecasting method of ground settlement to be occured in the future using in-situ monitoring data. The above both methods have some defects in application manner or in itself especially in very deep and soft clayey ground. In view of the lessons and experiences of soft ground improvement projects, several techniques were proposed for more accurate theorectical calculation of consolidation settlement as follows ; ① Subdivision of soft ground, ② Consideration of secondary compression, ③ Using the modified compression index, etc. And also, revised hyperbolic fitting method was suggested to minimize the error of predicted future settlement. In addition, revised De-Beer equation of immediate settlement of loose sandy soil was proposed to overcome the tendency to show too small settlement calculation results by original De-Deer equation. And also, considering the various effects of settlement delay in the improved ground by vertical drains, time-settlement caculation equation(Onoue method) was revised to match the tendency of settlement delay by using the characteristics of discharge capacity decreases of vertical drain with time elapse by the pattern of hyperbolic equation.

• Journal of the Korean Society of Food Culture
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• v.8 no.1
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• pp.55-62
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• 1993

These studies were conducted to: a) investigate work patterns and productivity indices, b) rate performance levels of employees and c) determine the suggested levels of personnel and labor hours for the effective labor control in school foodservice. Eighteen elementary school foodservices in Seoul were selected in order to analyze work patterns by the work sampling methodology. Allowance time and performance rating by VTR observation was done to determine the standardized labor hours. The results were as follows. The average percentage of each work function of the total work functions such as direct work function, indirect work function and delay were 65.57%, 8.12%, 26.31% respectively. The productivity index is 0.92 min/meal. The average working and delay hours per week of the foodservice director, foodservice employees and supply person were 33.64 hours, 23.25 hours, 38.52 hours respectively. The percentage of delay hours of total labor hours for foodservice employees and supply person were 42.27% and 24.0%. The standardized work hours and the appropriate levels of foodservice employees of 17 elementary school foodservices were examined: The average rating of the foodservice employees work was 1.19 and British Insulated Calendarer Cables (BICC) allowance rate was 19.40% on the average. The total work hours of foodservice employees were 172.64 hours per week and levels of personnel were 4.53 persons. BICC allowance rate was applied: The standardized work hours per week was 180.95 hours and appropriate levels of personnel were 4.11 persons based on legal 44 working hours.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.550-557
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• 2017

Ionospheric delay, which affect the accuracy of GNSS positioning, is generated by electrons in Ionosphere. Solar activity level, region and time could make change of this delay level. Dual frequency receiver could effectively eliminate the delay using difference of refractive index between L1 to L2 frequency. But, Single frequency receiver have to use limited correction such as ionospheric model in standalone GNSS or PRC(pseudorange correction) in Differential GNSS. Generally, these corrections is effective in normal condition. but, they might be useless, when TEC(total electron content) extremely increase in local area. In this paper, monitoring algorithm is proposed for local ionospheric anomaly using multiple reference stations. For verification, the algorithm was performed with specific measurement data in Ionospheric storm day (20. Nov. 2003). this algorithm would detect local ionospheric anomaly and improve reliability of ionospheric corrections for standalone receiver.

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.75-85
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• 2006

Currently, cross-section design can not reflect highway function and traffic volume, various construction. This research paper provides analysis of traffic accident type, improvement of traffic operation and safety, assessment for new cross-section standards of two-lane highway. Research show higher accident rate on 6$\sim$8.9m road than 9$\sim$12.9m road width in two-lane highway. Typical improvement is widening on lane and shoulder width. Simulation show large increase on 6$\sim$7m road delay-time in 1,200vph. In contrast 10$\sim$11.5m road shows slight change on delay-time. This research paper provides various cross-section construction by traffic volume in minor arterial and distributor two-lane highway. The new cross-section design provides adopting highway volume, various construction and flexibility.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.3
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• pp.43-52
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• 2004

This paper describes a method of evaluating seismic system performance of highway transportation network in California. The basic element that plays a crucial role in this study is the fragility information of highway bridges in Caltrans' (California Department of Transportation) freeway network. The bridge fragility information is expressed as a function of the ground motion intensity, such as peak ground acceleration (PGA) or peak ground velocity (PGV). Network damage was evaluated under the 1994 Northridge earthquake and scenario earthquakes. A probabilistic model was developed to determine the effect of repair of bridge damage on the improvement of the network performance as days passed after the event. As an example, the system performance degradation measured in terms of an index, “Drivers Delay”, is calculated for the Los Angeles area transportation system, and losses due to Drivers Delay with and without retrofit were estimated.