• Journal of Korea Water Resources Association
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• v.49 no.5
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• pp.399-410
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• 2016

In case of the application of Hazen-Williams C for design, operation or maintenance of water supply system, field situations always should be reflected on the factors. In this study, the relationships between C factors and influencing factors are analyzed using statistical techniques with 174 measured C factor data collected in periodic inspection for safety diagnosis in multi-regional water supply systems. To analyze their relationships, cross analysis, one-way ANOVA, correlation analysis were conducted. Analysis results showed that C factors had high correlations with both of elapsed year and pipe diameter and were relatively highly affected by coating material among influencing factors with the categorical type. On the other hand, elapsed year, pipe diameter and water type were meaningful influencing factors according to the results of multiple regression analysis. The Cluster analysis revealed that C factors had a tendency of being fundamentally classified on the basis of the elapsed year of about 20 years and the pipe diameter of 1500mm. Although C factors were generally greatly affected by elapsed year, size of pipe diameter relatively had an large influence on values of them in case of large diameter pipes. Lastly, It can be suggested that C factor estimation formulas using multiple regression analysis and clustering analysis in this study, can be applied as decision standards of C factor in multi-regional water supply systems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.341-348
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• 2016

Harbor facilities require long-term durability and safety, and also maintain the performance requirement until the durability life. However, existing harbor facilities are becoming superannuated with durable years and durability is declined by erosion of the sea and damage from sea. In addition, harbor facilities will be in demand for the expansion of harbor and offshore structures with rising economic power by enhancement of domestic industry and increase of import and export. Therefore, in this study, two kinds of nondestructive test (NDT) techniques (schmidt rebound hammer and ultrasonic sensor) are verified for the effective maintenance of underwater concrete structures including harbor facilities. Sea field applicability of Schmidt hammer and ultrasonic sensor was verified by comparing field test result with sea field test result and also deduced the compressive strength estimation equation by depth of the water. On the basis of the sea field test result, compressive strength estimation equation which was deduced by multiple regression analysis indicated highest accuracy compared to other equations, especially it will be more likely to be used in underwater because of the depth of water correction. In the future, if schmidt hammer and ultrasonic sensor which were invented as waterproofing are used with ROV (Remotely Operated Vehicle), it will be possible to make a diagnosis of high reliability for underwater concrete structures and set up a ubiquitous concept of NDT system.

• Korean Journal of Remote Sensing
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• v.35 no.5_2
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• pp.841-850
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• 2019

The purpose of this study is to strengthen the capability of rapid mapping for disaster through improving the positioning accuracy of mapping and fusion of multi-sensing point cloud data derived from Unmanned Aerial Vehicles (UAVs) and disaster investigation vehicle. The positioning accuracy was evaluated for two procedures of drone mapping with Agisoft PhotoScan: 1) general geo-referencing by self-calibration, 2) proposed geo-referencing with optimized camera model by using fixed accurate Interior Orientation Parameters (IOPs) derived from indoor camera calibration test and bundle adjustment. The analysis result of positioning accuracy showed that positioning RMS error was improved 2~3 m to 0.11~0.28 m in horizontal and 2.85 m to 0.45 m in vertical accuracy, respectively. In addition, proposed data fusion approach of multi-sensing point cloud with the constraints of the height showed that the point matching error was greatly reduced under about 0.07 m. Accordingly, our proposed data fusion approach will enable us to generate effectively and timelinessly ortho-imagery and high-resolution three dimensional geographic data for national disaster management in the future.

• Journal of Korea Entertainment Industry Association
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• v.13 no.4
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• pp.229-240
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• 2019

Korea is experiencing various disasters both natural and artificial. This study is descriptive research designed to examine the perception of the disaster response ability of fire-paramedics during the response stage of disaster management. The subjects of this study were EMT-P's who had more than 2 years of experience in the field at a fire station in G Province. The questionnaire, including the items for the sub-factors of the field response ability, were prepared and 161 final questionnaires were collected and analyzed with the SPSS program. The mean scores of triage ability, patient treatment ability, patient transfer ability, disaster support ability, and disaster response speed were 3.53, 3.68, 3.66, 2.95, and 3.44, respectively. As a result of multiple regression analysis, variables affecting the speed of disaster response were in the order of patient treatment ability, patient transfer ability, and disaster support ability. In conclusion, fire-paramedics will have to consider the ability to treat patients, transfer patients, and disaster support to improve disaster response speed, and, ultimately, disaster response guidelines should be developed to improve disaster response capabilities.

• Journal of the Korea Institute of Building Construction
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• v.16 no.4
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• pp.349-357
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• 2016

Recently, the quantity of risk in construction project has been inflated due to the fact that current construction projects have been large and complicated. Therefore, a study on the risk management methods is necessary that can predict and respond to the need in complicated modern construction projects. In this study, the objective is to analyze the cause of accident in actual construction sites and develop a risk assessment model based on insurance claims records. To reach the goal of this study, first, the frequency and severity of accidents are analyzed the causes of accidents based on the classification; progress rate, season, and total construction costs. Second, a risk assessment model is developed by utilizing a multiple regression analysis. The dependent variable is loss ratio of material damage and three categories; natural hazards, geographic information, and construction method & ability, are used as the independent variables. The model's adjusted R-square is 0.455. The contributions of this study will be used as a material for a quantitative risk analysis model development and review of the construction risk factors for future study.

• 한국노년학
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• v.37 no.2
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• pp.349-368
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• 2017

The purpose of this study is to empirically structure the patterns of baby boomer retirees'consumption and their effects on depression in later life. Using the 5th wave of Korea Retirement and Income Study(KReIS) in 2013, of baby boomers born in 1955 to 1963, we analyzed those who were completely retired(n=420). The Latent Profile Analysis(LPA) classified the empirical patterns of consumption and then a multiple regression analyzed the effect of consumption patterns on depression among these baby boomer retirees. The LPA results showed that the consumption patterns consist of five groups: (1) Basic life-oriented class(26.9%), (2) Balanced consumption class(29.3%), (3) Social life-oriented class(18.3%), (4) Leisure-oriented class(18.5%), and (5) Education-oriented class(7.0%). Baby boomer retirees' depression was associated with their consumption patterns. Specifically, the basic life-oriented class showed significantly lower depression than the education-oriented class. Other correlates such as higher education, having no spouse, lower subjective health, greater limitations in physical functions, having a diagnosed disability, having fewer children, higher dissatisfaction with leisure activities, and lower self-perceived economic status were associated with higher levels of depression in this study. These findings suggest meaningful implications for gerontological policy and practice for baby boomer retirees in Korea. In light of vulnerable retirement preparation, social services specialized for baby boomers should consider financial education for revamping consumption scale beyond asset management and long-term case management of pre and post retirement cases.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.4
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• pp.48-64
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• 2008

The aim of this research is to set a systemic Ecological Landscape Planning Model to cope with the destroyed landscape problems which was caused by massive development project and thoughtless development in country areas. The summary of research result are as follows. As a result of analysis on domestic and international literature, there are 60 planning index items which are nature conservation area, landscape conservation area, and build and manage wetland biotope and so on. total number of planning index is 34 after finalizing the physical index items. As a result of on-spot research, all 34 planning index after literature analysis is existing. Also, there are 38 finally-selected index which includes 4 added planning index in the process of research like natural vegetation in frequently-used spot. As a result of importance analysis on detailed planning index, most are above 5 points, which is relatively high. As a result of factor analysis on patterning for the detailed planning index, it was classified with seven elements. The first Ecological Landscape Planning model was set with integrated analysis on result of pattering for the detailed planning index and importance of detailed planning index. Based on first model, to make more systematic landscape, the analysis of MCB was conducted. As a result of MCB analysis according to planning index, it is confirmed that each planning index shows maximum. As a result of importance analysis on the 9 plans keynote, the average importance point was 4.62 for conservation area and 4.54 for enrichment area respectively. By integrating the result of importance analysis on basic aims of the first model, MCB analysis and plans, we set the second Ecological Landscape Planning model. In vertical transition, for example, 'conservation area' showed the importance point above 5.2 for all planning index except setting recreational space. Also, the analysis on parallel structure showed that relation between 'additional improvement, management, and connection' and other planning index is above 5.3 and importance on correlation with 'the part which should be protected from nature and landscape' marked 6.07 which is the highest.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.297-307
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• 2010

Recently, maintenance engineering and technology for civil and building structures have begun to draw big attention and actually the number of structures that need to be evaluate on structural safety due to deterioration and performance degradation of structures are rapidly increasing. When stiffness is decreased because of deterioration of structures and member cracks, dynamic characteristics of structures would be changed. And it is important that the damaged areas and extent of the damage are correctly evaluated by analyzing dynamic characteristics from the actual behavior of a structure. In general, typical measurement instruments used for structure monitoring are dynamic instruments. Existing dynamic instruments are not easy to obtain reliable data when the cable connecting measurement sensors and device is long, and have uneconomical for 1 to 1 connection process between each sensor and instrument. Therefore, a method without attaching sensors to measure vibration at a long range is required. The representative applicable non-contact methods to measure the vibration of structures are laser doppler effect, a method using GPS, and image processing technique. The method using laser doppler effect shows relatively high accuracy but uneconomical while the method using GPS requires expensive equipment, and has its signal's own error and limited speed of sampling rate. But the method using image signal is simple and economical, and is proper to get vibration of inaccessible structures and dynamic characteristics. Image signals of camera instead of sensors had been recently used by many researchers. But the existing method, which records a point of a target attached on a structure and then measures vibration using image processing technique, could have relatively the limited objects of measurement. Therefore, this study conducted shaking table test and field load test to verify the validity of the method that can measure multi-point displacement responses of structures using image processing technique.

• Korean Security Journal
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• no.25
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• pp.147-164
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• 2010

A variety of work zone including road single-sharing construction add surrounding disorder and increase inconvenience of vehicles and pedestrians and furthermore danger of traffic accidents, which sometimes result in human life damages. Traffic delay due to vehicles and users generating in the course of using large-scale multiplex facilities bring about a great economic loss. Now, a lot of regulations and laws related to traffic safety system on construction sites etc. are established, but can not display efficacy desirably. It brings about continuous economic loss due to human life accidents and delay. For the purpose of solving the problems, it is necessary to import systems such as traffic inducement Security (Japan) and traffic controller (CANADA, USA) This article suggest how improve civil safety and reduce Social cost. therefore This thesis aims at analyzing advanced cases of foreign countries, looking into Korean status, and presenting importing ways of traffic inducement Security appropriate to Korea. It is reasonable to grant grade1, grade2, and technical experts to traffic inducement Security who pass regulated educations and examinations. In addition, by reversing regulations and laws, it is necessary only those who have the licenses of traffic induction guarder etc. can establish construction sites and disordered places on roads. Theory educations for education time must include basic educations and expert educations. Basic educations must include understanding regulations and laws and understanding affairs. Expert educations must include traffic control, safety educations, understanding of traffic accidents, operation of traffic control facilities, and traffic accident settlements. Traffic affairs educations must include traffic induction affairs in sites (hand signals, safety material establishment, traffic accident settlements, and urgent treatments).

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.759-767
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• 2006

This paper presents a method to estimate the setting time of concrete using super retarding agent(SRA) and fly ash(FA) under various curing temperature conditions by applying maturity based on equivalent age. To estimate setting time, the equivalent age using apparent activation energy($E_a$) was applied. Increasing SRA content and decreasing curing temperature leads to retard initial and final set markedly. $E_a$ at the initial set and final set obtained by Arrhenius function showed differences in response to mixture type. It is estimated to be from $24{\sim}35KJ/mol$ in all mixtures, which is smaller than that of conventional mixture ranging from $30{\sim}50KJ/mol$. Based on the application of $E_a$ to Freisleben-Hansen and Pederson's equivalent age function, equivalent age is nearly constant, regardless of curing temperature and SRA contents. This implies that the concept of maturity is applicable in estimating the setting time of concrete containing SRA. A high correlation between estimated setting time and measured setting time is observed. Multi-regression model to determine appropriate dosage of SRA reflecting FA contents and equivalent age was provided. Thus, the setting time estimation method studied herein can be applicable to the concrete containing SRA and FA in construction fields.