• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.285-292
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• 2006

The objective of this study is to introduce the development of the first Korean full-scale APT(Accelerated Pavement Tester) and to compare the performances of general dense grade asphalt mixture and modified asphalt mixtures as the first running of the tester. The tests evaluated the rutting resistance for dense grade mixture and three different modified asphalt mixture under three different temperature conditions (25-30, 40, $50^{\circ}C$). The results of the testing were compared with the laboratory test results. Results of the tests indicated that the all the modified asphalt sections showed higher rutting resistance than the dense grade section. Especially, the difference was more noticeable at higher temperature condition. Additionally, $G^*/sin{\delta}$ is found out to be an important factor for permanent deformation prediction whereas the resilient modulus was not.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.35-44
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• 2020

The purpose of this study is to elaborate the request for proposal (RFP) for the localization parts development support project of core parts carried out by the Defense Agency for Technology and Quality. The RFP is the most important document throughout the localization parts project, including project announcement and developer selection, design and test of the development product, final evaluation, and standardization of the project. However, if the RFP is not established at the beginning of the project, there is an increased risk of business failure due to frequent changes by various reasons. In this study, we recognized the necessity of elaboration of RFP and applied the AHP method for quantitative elaboration. Eight requirements of the RFP related to the mechanical/electrical performance of localized development products and three elaboration methods for each requirement were designed in a hierarchical structure, and each weight was calculated by applying the 5-point scale AHP method. The AHP survey was conducted with 20 developers participating in the localization parts project, and the consistency ratio of the AHP survey result was less than 0.1. The elaboration method with the highest value among the calculated weights is classified, and the analysis results and future research directions of the elaboration method are presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.133-140
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• 2016

The Ministry of Land, Infrastructure and Transport has introduced low-floor buses, which are convenient for passengers getting on and off the bus and for the handicapped. The standard bus model is 11 m long and uses compressed natural gas (CNG). However, this model has drawbacks in narrow rural road conditions such as those in farming and fishing villages and mountainous areas, as well as difficulty in refueling since CNG facilities are not readily available. In this study, running resistance values were obtained by coasting performance tests on actual roads using a Tata Daewoo LF-40 model with three different weight conditions: curb vehicle weight (CVW), half vehicle weight (HVW), and gross vehicle weight (GVW).The test methods include WHVC, NIER-06, and constant-speed driving at 60 km/h. These tests were used to measure the fuel economy of vehicles other than the target vehicles to obtain the combined fuel economy. The energy efficiency was highest in the case of CVW. In the WHVC mode, the fuel consumption rates of HVW and GVW were typically 3.5% and 12% higher than that of CVW, respectively. In constant-speed driving, the fuel efficiency of HVW was higher than that of CVW. Further research is required to analyze the exhaust gas data.

• The Journal of the Acoustical Society of Korea
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• v.41 no.2
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• pp.210-217
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• 2022

Passive source depth estimation has been studied for decades since the source depth can be used for target classification, target tracking, etc. The purpose of this paper is to solve the problem of ambiguity in the previous paper [S.-il. Cho et al. (in Korean), J. Acoust. Soc. Kr. 38, 120-127 (2019)] that source depth is estimated in two points. The patterns of phase shift of Channel Impulse Response(CIR) reflected in ocean surface and bottom is used for removing ambiguity of the source depth estimation, and after removing ambiguity, source depth is estimated at one point through the intersection of CIR. In order to extract CIR in case of unknown source signal and continuous signal or noise, Ray-based blind deconvolution is used. The proposed algorithm is demonstrated through numerical simulation in ocean waveguide.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.689-696
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• 2017

The practical applications of ordinary high-fluidity concrete have been limited due to several drawbacks, such as high hydration heat, high amount of shrinkage, and non-economic strength development. On the other hand, due to its advantages, such as improvement of construction quality, reduction of construction cost and period, the development of high-fluidity concrete is a pressing need. This study examined the properties of high-fluidity concrete, which can be manufactured on the low binders using a viscosity agent to prevent the segregation of materials. The optimal viscosity agent was selected by an evaluation of the mechanical properties of high-fluidity concrete among six viscosity agents. The acrylic type and urethane type viscosity agents showed the best performance within the range where no material separation occurred. The mechanical properties were evaluated to examine the optimal amount of AC and UT viscosity agent added by mixing two viscosity agents according to the adding ratio and blending them together with high performance water reducing agent. When the ratio of the AC : UT viscosity agents was 5:5, it was most suited for high-fluidity concrete with low binders by increasing the workability and effect of the reducing viscosity.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.51-58
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• 2008

Development of a new design guide which is based on empirical-mechanistic concept for pavement design is in action. It is called AASHTO 2002 Design Guide in USA and the KPRP(Korean Pavement Research Project) in Korea. The material characteristic of hot mix asphalt is a key role in the design guide. Therefore it is urgent to get a proper materials database, especially the dynamic modulus of hot mix asphalt. In this research, dynamic modulus test, which is based on aged asphalt binder, has been carried out and proposed the predicted equation of dynamic modulus. Nine different hot mix asphalt with three different asphalt binder have been used for the dynamic modulus test. Short-term aging, which is covers the time for the production of asphalt plant, transportation, lay-down, and compaction, can be simulated at $135^{\circ}C$ with 2 hour curing. Long-term aging has been carried out for a performance period of asphalt pavement. The dynamic modulus of asphalt pavement increases with aging time. As the nominal aggregate size increases, the change of dynamic modulus is not big.

• Journal of the Korean Society for Nondestructive Testing
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• v.17 no.2
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• pp.108-113
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• 1997

Ultrasonic testing is one of the most widely used method of nondestructive testing for pre-service inspection(PSI) & in-service inspection(ISI) in structures of bridges, power plants, chemical plants & heavy industrial fields. It is very important to estimate safety, life, quality of structures. Also, a lot of research for quantities evaluation & analyses inspection data is proceeding. But traditional portable ultrasonic flaw detector had been following disadvantages. 1) Analog ultrasonic flaw detector decreased credibility of ultrasonic test, because it is impossible for saving data & digital signal processing. 2) Stand-alone digital ultrasonic flaw detector cannot effectively evaluate received signals because of lack of its storage memory. To overcome this shortcoming, we develop the computer based ultrasonic flaw detector for nondestructive testing. It can store the received signal and effectively evaluate the signal, and then enhance the reliability of the testing results.

• Korean Journal of Poultry Science
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• v.45 no.3
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• pp.219-228
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• 2018

This study was conducted twice to investigate egg purchase behavior and perception on animal welfare of Korean consumers. This study included women, who were the main decision makers and caretakers in the household, and men with one-person household. This survey was conducted with by the Computer Assisted Web Interview and Gang Survey methods. On the key considerations factor, the highest response rate was considered to be 'price', and the response rate of considering 'packing date' increased in the second survey. At a reasonable price based on 10 eggs, the response rate was the highest at 53.8% and 42.9% in both the first and second surveys and the appropriate price averages were 2,482 won and 2,132 won, respectively. The highest rate of purchase of egg consumers from 'Large Mart' followed by 'Medium sized supermarket' and 'Chain supermarket'. As for the awareness about animal welfare, the recognition ratio (73.5%) was higher in the result of the second survey than the first. The cognitive period of animal welfare was 59.0% before the insecticide egg crisis and 41.0% thereafter. Regarding whether or not they have ever seen an animal welfare certification mark and an animal welfare animal farm certification mark, 59.6% of respondents said that they saw it for the first time and 37.6% answered that they knew the animal welfare certification mark. On the animal welfare system, the 'free-range' response rate was the highest at 85.8%. The 'free-range' fit response decreased by 34.2%p, while the 'barn' and 'European type' fit response increased by 13.2%p and 24.1%p, respectively. The number of 'I have never seen' and 'I have ever eaten' responses to the recognition and eating experience of animal welfare certified eggs decreased while the number of those who answered 'Have ever seen' and 'Have eaten' increased. The answer of purchasing animal welfare certified eggs at department stores, organic farming cooperatives, and internet shopping malls was higher than that of buying conventional eggs. Of the total respondents, 92.0% were willing to purchase an animal welfare egg before the price was offered, but after offering the prices of animal welfare eggs, the intention to purchase was 62.7%, which was about 30%p lower than before. The reason for purchasing an animal welfare certified egg was the highest score of 71.0% for 'I think it is likely to be high in food safety', and 38.1% for 'I think the price is high' for lack of intention to purchase. In the sensory evaluation of animal welfare eggs, egg color and skin texture of conventional eggs were significantly higher than those of certified welfare eggs (P<0.05), and boiled eggs showed that egg whites of animal welfare certified eggs were more (P<0.05). As a result, the results of this study will contribute to the activation of the animal welfare certification system for laying hens by providing basic data on consumer awareness to animal welfare certified farmers.

• Korean Journal of Food Science and Technology
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• v.5 no.1
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• pp.16-24
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• 1973

Breads were made from composite flours based on domestic resources and their quality was assessed to obtain the following results. 1) When barley bread was made according to the formula for standard wheat bread, its specific loaf volume (SLV) was quite low (1.3 at 100% addition of water) in comparison with 3.3 for wheat bread. Addition of 10% defatted soy flour increased its SLV to 1.7 (at 100% water). Among various flour-improving additives, the use of 1.5% GMS + 0.5% CSL gave best results (SLV: 2.0 at 100% water). Admixture of wheat flour with the composite flour based on barley was most effective. Replacement of barley flour with 25% wheat flour gave SLV of 2.8 (at 90% water) and that with 50% wheat flour gave SLV of 3.2 (at 90% water), comparable to standard wheat bread with respect to loaf volume, color and texture. 2) Sweet potato bread had the characteristics of turning black-brown on baking. Use of 20% defatted soy flour and GMS + CSL gave higher SLV (1.9 at 100% water). Addition of wheat flour at 25% or 50% level to the composite flour based on sweet potato flour gave SLV of 2.3 and 2.6, respectively, at 90% water and its color and texture were improved 3) Potato flour was different from sweet potato flour in baking, the effect of GMS + CSL being quite low. Bread from corn flour was different from barley flour bread and defatted rice bran was not suitable for bread-making. 4) Bread was made from following composite flours based on naked barley and sweet potato flours along with the use of proper additives: (a) naked barley flour + defatted soy flour + wheat flour (45 : 10 : 45) (b) naked barley flour + defatted soy flour + wheat flour (67 : 10 : 23) (c) naked barley flour + defatted soy flour (90 : 10) (d) sweet potato flour + defatted soy flour + wheat flour (40 : 20 : 40) (e) sweet potato flour + defatted soy flour (60 : 20 : 20) Sensory evaluation of above breads in comparison with standard wheat bread (So) gave the following decreasing order of scores, So>(a)>(b)>(c)>(e)>(d) and Duncan's multiple range test showed that bread (a) was not different from standard wheat bread significantly at 5% level, in overall evaluation including color, texture, taste and flavor.

• Journal of Korean Home Economics Education Association
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• v.29 no.1
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• pp.125-143
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• 2017

This program aimed at preparing the pre-service teachers to teach about North Korean family life culture to secondary school students, by promoting the understanding and acceptance of cultural differences between the two Koreas. Based on the literature review, the educational contents were developed to reflect general aspects of North Korean family life. The program was implemented with 35 undergraduate students in a home economics teacher education program. The program consists of 15 units of 150-minute instructional sessions. The first three introductory sessions dealt with the definitions of family life culture and multiculturalism, as well as a historical review of South-North relationship. The following nine sessions were devoted to North Korean family life culture in five different domains: consumption and leisure, family and child-caring, food and dietary life, housing and neighborhood life, and clothing/fashion. During the final two weeks, pre-service teachers conducted mock-teaching. For evaluation, pre- and post-session scores on general teaching efficacy and understanding of cultural differences were compared using paired t-tests. The pre-/post-test results confirmed that the program was successful in promoting the understanding and acceptance of cultural differences between two Koreas of pre-service teachers.