• 한국재료학회지
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• 제29권10호
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• pp.647-655
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• 2019

In order to analyze the effect of hot asymmetric rolling on the microstructure and texture of aluminum alloy and to investigate the effect of the texture on the formability and plastic anisotropy of aluminum alloy, aluminum 6061 alloy is asymmetrically rolled at room temperature, $200^{\circ}C$, $350^{\circ}C$, and $500^{\circ}C$, and the results are compared with symmetrically rolled results. In the case of asymmetric rolling, the equivalent strain (${\varepsilon}_{eq}$) is greatest in the upper roll part where the rotational speed of the roll is high and increases with increasing rolling temperature. The increase rate of the mean misorientation angle with increasing temperature is larger than that during symmetrical rolling, and dynamic recrystallization occurs the most when asymmetrical rolling is performed at $500^{\circ}C$. In the case of hot symmetric rolling, the {001}<110> rotated cube orientation mainly develops, but in the case of hot asymmetric rolling, the {111}<110> orientation develops along with the {001}<100> cube orientation. The hot asymmetric rolling improves the formability (${\bar{r}}$) of the aluminum 6061 alloy to 0.9 and reduces the plastic anisotropy (${\Delta}r$) to near zero due to the {111}<110> shear orientation that develops by asymmetric rolling.

• Earthquakes and Structures
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• 제17권4호
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• pp.411-424
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• 2019

In this study, a numerical model of a shield tunnel with an assembled segmental lining was built. The seismic response of the segmental lining of the section of the shield tunnel in Line 1 of the Chengdu Metro is analyzed as it passes through the interface of sand-cobble and mudstone layers. To do so, the node-stress seismic-motion input method was used to input the seismic motion measured during the 2008 Wenchuan earthquake, and the joint openings and dislocations associated with the earthquake action were obtained. With reference to the Ethylene-Propylene-Diene Monomer (EPDM) sealing gaskets used in the shield tunnels in the Chengdu Metro, numerical simulation was applied to analyze the contact pressure along the seepage paths and the waterproof property under different joint openings and dislocations. A laboratory test on the elastic sealing gasket was also conducted to study its waterproof property. The test results accord well with the numerical results and the occurrence of water seepage in the section of the shield tunnel in Line 1 of the Chengdu Metro during the 2008 Wenchuan earthquake was verified. These research results demonstrate the deformation of segmental joint under earthquake, also demonstrate the relationship between segmental joint deformation and waterproof property.

• 한국전산구조공학회논문집
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• 제34권5호
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• pp.309-317
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• 2021

이 논문에서는 박스형 전력구의 지진응답해석에 사용되는 응답진도법의 보수성을 평가하였다. 이를 위해 25가지 전력구 단면과 각 전력구에 대한 2개의 지반조건을 고려한 총 50개 예제를 선정하였다. 응답진도법의 보수성을 평가하기 위해 동적 지반-구조물 상호작용을 고려한 정밀해석법에 의한 응답과 비교하였다. 비교결과, 정밀해석 응답에 대한 응답진도법에 의한 응답의 비로 정의한 응답비의 평균이 1.0에 근접하며, 응답비의 표준편차도 5% 이내로 매우 작아서, 응답진도법에 의한 해석이 정밀해석법과 일관됨을 알 수 있었다. 마지막으로 응답진도법에 의한 응답에 하중계수 1.1을 적용하면 전력구의 보수적인 내진설계가 가능할 것으로 나타났다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권2호
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• pp.800-813
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• 2021

With the advent of 5G communications, internet of vehicles technology has been widely used in vehicles. Then the dynamic spread of information between vehicles began to come into focus with more research. It is well known that the identification of nodes with great spread influence has always been a hot topic in the field of information spreading. Most of the existing work measures the propagation influence by degree centrality, betweenness centrality and closeness centrality. In this paper, we will identify influential vehicle nodes based on the mobility characteristics of vehicles to explore the information spreading between vehicles in VANETs. Different from the above methods, we mainly explore the influence of the radius of gyration and vehicle kilometers of travel on information spreading. We use a real vehicle trajectory data to simulate the information transmission process between vehicles based on the susceptible-infected-recovered SIR model. The experimental results show that the influence of information spreading does not enhance with increasing radius of gyration and vehicle kilometers of travel. The fact is that both the radius of gyration and the distance travelled have a significant influence on information spreading when they are close to the median. When the value of both is large or small, it has little influence on information spreading. In view of this results, we can use the radius of gyration and vehicle kilometers of travel to better facilitate the transmission of information between vehicles.

• 방송공학회논문지
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• 제23권6호
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• pp.813-823
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• 2018

끊김 없는 UHD 콘텐츠 스트리밍 서비스를 제공하기 위해서는 많은 가용 대역폭이 필요하다. 기존의 HTTP 적응적 스트리밍 방식은 정상 상태에서 가용 대역폭보다 낮은 품질의 비디오 세그먼트를 주기적으로 요청하여 다운로드 받는다. 정상 상태에서는 가용 대역폭과 콘텐츠의 인코딩 율에 차이에 따라 On-Off 구간의 패턴이 반복되어 발생하고, 반복적인 Off 구간에 의해서 대역폭을 효율적으로 사용하지 못하는 문제점이 있다. 지연과 손실률이 높고 대역폭 변화가 심한 무선 환경에서는 네트워크의 가용대역폭을 부정확하게 측정하기 때문에 문제점이 심화된다. 본 논문에서는 무선 환경에서 UHD 콘텐츠의 효율적인 대역폭 활용을 위한 HTTP 적응적 스트리밍의 세그먼트 스케줄링 기법을 제안한다. 제안하는 기법은 OFF 구간의 빈도수를 줄이기 위해 한 번의 요청 메시지에 여러 세그먼트를 동시에 요청하는 집단 세그먼트 방식이다. 실험을 통해서 제안하는 기법이 대역폭 이용율을 향상시키는 것을 확인 하였다.

• 한국건설순환자원학회논문집
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• 제6권4호
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• pp.319-323
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• 2018

페로니켈 슬래그는 페로니켈의 제련과정에서 발생하는 산업부산물로, 냉각 방법에 따라 서냉 페로니켈 슬래그와 수쇄 페로니켈 슬래그로 구분된다. 본 연구의 목적은 서냉 페로니켈 슬래그(air-cooled ferronickel slag, ACFNS) 잔골재를 이용한 콘크리트의 역학적 특성 및 동결융해 저항성을 평가하는 것이다. 이를 위하여 물-시멘트비 50%에 대해서 ACFNS 혼입률을 잔골재용적비로 7가지 수준(0%, 20%, 30%, 40%, 50%, 70%, 100%)으로 변화시켜 ACFNS 잔골재를 이용한 콘크리트를 제작하였다. 실험결과로부터, ACFNS 잔골재 콘크리트의 압축강도 및 정탄성계수는 ACFNS의 혼입률이 증가할수록 커지고, 동결융해 저항성은 동결융해 300 사이클 동안 상대동탄성계수가 90% 이상으로 나타난 기준 콘크리트와 유사한 것으로 나타났다.

• 대한간호학회지
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• 제49권4호
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• pp.398-410
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• 2019

Purpose: This study used a system dynamics methodology to identify correlation and nonlinear feedback structures among factors affecting adolescent cyberbullying victims (CV) in Korea and to construct and verify a simulation model. Methods: Factors affecting CV were identified by reviewing a theoretical background in existing literature and referencing various statistical data. Related variables were identified through content validity verification by an expert group, after which a causal loop diagram (CLD) was constructed based on the variables. A stock-flow diagram (SFD) using Vensim Professional 7.3 was used to establish a CV model. Results: Based on the literature review and expert verification, 22 variables associated with CV were identified and the CLD was prepared. Next, a model was developed by converting the CLD to an SFD. The simulation results showed that the variables such as negative emotions, stress levels, high levels of conflict in schools, parental monitoring, and time spent using new media had the strongest effects on CV. The model's validity was verified using equation check, sensitivity analysis for timestep and simulation with 4 CV adolescent. Conclusion: The system dynamics model constructed in this study can be used to develop intervention strategies in schools that are focused on counseling that can prevent cyberbullying and assist in the victims' recovery by formulating a feedback structure and capturing the dynamic changes observed in CV. To prevent cyberbullying, it is necessary to develop more effective strategies such as prevention education, counseling and treatment that considers factors pertaining to the individual, family, school, and media.

• 대한지역사회영양학회지
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• 제26권5호
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• pp.363-381
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• 2021

Objectives: This study examined the Korean elderly's dietary intake status, subjective health-related perception and chronic disease prevalence among age groups. Associations of dietary quality with subjective health-related perception and chronic diseases were also examined. Methods: Based on data from the 7th National Health and Nutrition Examination Survey, a total of 3,231 elderly were selected and categorized into 4 age groups of '65 ~ 69', '70 ~ 74', '75 ~ 79' and 'over 80'. Nutrient intakes, proportions of those with insufficient nutrient intakes, Korean Healthy Eating Index (KHEI), some subjective health-related perceptions and prevalence of major chronic diseases were compared according to the age groups. Differences in the subjective health-related perceptions and odds ratios of the chronic diseases according to the quartile levels of KHEI within the same age group were analyzed. Results: With the increase of age, several nutrient intakes (P < 0.001) and KHEI scores significantly decreased (P < 0.01). In women, activity restriction increased (P < 0.05), and EQ-5D score decreased with age (P < 0.001). Prevalence of hypertension (P < 0.0001), hypercholesterolemia (P < 0.05) and anemia (P < 0.01) significantly increased, while hypertriglyceridemia (P < 0.01) significantly decreased only in men. Obesity prevalence decreased, while underweight prevalence increased (P < 0.05). Subjective health status, EQ-5D score and PHQ-9 score significantly improved as KHEI score increased in certain age groups of women (P < 0.05). Odds ratio of hypercholesterolemia significantly increased with the increase of KHEI score in 65 ~ 69-year-old women. However, hypertension and anemia significantly decreased with the increase of KHEI score in 75 ~ 79-year-old women (P < 0.05). Conclusions: The study findings suggest that nutrition management and policy for the Korean elderly need to apply a segmented age standard that can better reflect their dynamic characteristics.

• Physical Therapy Rehabilitation Science
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• 제10권1호
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• pp.1-9
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• 2021

Objective: Joint mobilization for arthrokinematics altered by the positional fault of chronic ankle instability (CAI) is an effective intervention for stabilization. In this study, we compared the effects of ankle dorsi flexion range of motion (DFROM) and dynamic balance ability (DBA) in CAI patients via passive joint mobilization (PJM), a method traditionally performed in previous studies, and active joint mobilization (AJM), a method that can have a greater effect on cortical excitability with spontaneous movements. Design: Single-blind two-arm randomized controlled trial Methods: A total of 30 participants were registered: 15 each to the PJM and AJM groups. Each participant received a total of 10 intervention sessions, 10 minutes per session, 5 times a week for 2 weeks. PJM used Maitland's mobilization method to apply joint mobilization with talus in the posterior direction and AJM used an angular joint motion to induce patient's voluntary motion of medial malleolus anterior gliding and lateral malleolus posterior gliding, respectively. DFROM of the ankle was measured by using tape and DBA was evaluated by using the balance system. Results: Significant improvement was observed after intervention in both the PJM and AJM groups except for the DBA-anterior and DBA-right variables of the PJM group. There were statistically significant differences between the AJM and PJM groups in the DFROM, DBA-anterior, DBA-posterior, and DBA-right variables. Conclusions: The overall improvement of DFROM and DBA was found to be more effective in joint mobilization including voluntary movement. When it is accompanied by voluntary movement, it further affects the neuromuscular system of the ankle.

• 한국프랜차이즈경영연구
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• 제10권3호
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• pp.13-23
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• 2019

Purpose - The recent franchise industry is rapidly developing. Some franchisees have a low barriers to entry and competition among companies is intensifying. In this dynamic competitive environment, companies need to focus on customer preferences, quality, and technical interfaces to gain competitive advantage. As a result, companies are required to measure the performance of service values in order to provide differentiated services from competitors. In the franchise industry, customer experience marketing of service values will enable companies to create new businesses. Franchise firms should explore a variety of services to increase service value and reduce failures. Research design, data, methodology - The questionnaire of this study was based on the previous research. Surveys were conducted on panels of online surveys. Surveys were conducted on the panel who had visited the restaurant franchise within the past month. The survey was conducted for about 7 days from February 13, 2019 to February 19, 2019. Total 300 samples, 293 were used in the analysis except for seven unfair questionnaires. Results - The findings of this study are as follows: Emotional, monetary, and reputation values have positive effects on cognitive and affective attitudes. Quality value and behavioral value did not effect cognitive attitude and affective attitude significantly. In addition, affective attitude has positive effect on loyalty, but cognitive attitude did not significant effect on loyalty. Conclusions - First, food-service franchise company should develop a service that enables customers to use the store conveniently. We need to develop a comfortable environment for our customers and provide intangible services. Second, food-service franchise company should provide a reasonable price service. Food-service franchise company needs to sell a high quality menu at a reasonable price to generate profits. Third, food-service franchise companies need to strategically respond to their reputation. In other words, food-service franchise company needs to constantly monitor the reputation of its customers and respond appropriately to market conditions. Fourth, food-service franchise company needs to develop a service method capable of emotional interaction with customers. Food-service franchise firms need to develop ongoing service methods and educate their staff.