• Geomechanics and Engineering
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• 제29권6호
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• pp.697-706
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• 2022

In order to explore the stable anchoring conditions of coal side under the mining disturbance of soft section coal pillar in Wangcun Coal Mine of Chenghe Mining Area, the distribution model of the anchoring support pressure at the coal pillar side was established, using the strain-softening characteristics of the coal to study the distribution law of anchoring coal side support pressure. The analytical solution for the reinforcement anchorage stress in the coal pillar side was derived with the inelastic state mechanical model. The results show that the deformation angle of the roadway side and roof increases with the roof subsidence due to the mining influence at the adjacent working face, the plastic deformation zone extends to the depth of the coal side, and the increase of anchorage stress can effectively control the roof subsidence and further deterioration of plastic zone. The roadway height and the peak support pressure have a certain influence on the anchorage stress, the required anchorage stress of the coal side rises with the roadway height and the peak support pressure. The required anchorage stress of the coal pillar side decreases as the cohesion between the coal seam and the roof and floor and the anchor length increases. Then, applied the research result to Wangcun coal mine in Chenghe mining area, the design of anchor cable reinforcement support was proposed for the section of coal pillars side that has been anchored and deformed, which achieved great results and effectively controlled the convergence and deformation of the side, providing a safety guarantee for the roadway excavation and mining.

• Structural Engineering and Mechanics
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• 제83권5호
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• pp.655-669
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• 2022

Passive vibration control devices like tuned liquid column dampers (TLCD) not only significantly reduce buildings' vibrations but also can serve as a water storage facility. The recently introduced modified form of TLCD known as tuned liquid column ball damper (TLCBD) suppressed external vibration efficiently compared to traditional TLCD. For excellent performance, the mass ratio of TLCBD should be in the range of 5% to 7%, which does not include the mass of the ball. This additional mass of the ball increases the overall structure mass. Therefore, in this paper, an effort is made to reduce the mass of TLCBD. For this purpose, a new modified version of TLCBD known as tuned liquid column hollow ball damper (TLCHBD) is proposed. The existing mathematical modeling of TLCBD is used for this new damper by updating the numerical values of the mass and mass moment of the ball. Analytically the optimal design parameters are obtained. Numerically the TLCHBD is investigated with a single degree of freedom structure under harmonic and seismic loadings. It is found that TLCHBD performance is similar to TLCBD in both loadings' cases. To validate the numerical results, an experimental study is conducted. The mass of the ball of TLCHBD is reduced by 50% compared to the ball of TLCBD. Both the arrangements are studied with a multi-degree of freedom structure under harmonic and seismic loadings using a shake table. The results of the experimental study confirm the numerical findings. It is found that the performance behavior of both the dampers is almost similar under harmonic and seismic loadings. In short, the TLCHBD is lighter in weight than TLCBD but has a similar vibration suppression ability.

• 한국구조물진단유지관리공학회 논문집
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• 제27권1호
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• pp.95-102
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• 2023

본 연구에서는 다양한 래티스 단부 지점조건을 갖는 철선일체형 데크플레이트의 구조성능을 유한요소해석을 통하여 평가하였다. 해석결과, 래티스 단부에서 풋의 위치가 지점부 구조부재 위에 위치하는 경우가 그렇지 않은 경우에 비해 시스템 강성이 더 큰 것으로 나타났다. 또한 래티스 풋이 지점부에 위치하는 경우, 단부 직봉이 전체 데크플레이트 시스템의 강성과 강도에 미치는 영향은 무시할 정도로 작았다. 특히 래티스 풋의 길이가 40mm 보다 작지 않을 때에는 단부 직봉이 설치되지 않아도 무방한 것으로 평가되었다. 래티스 단부 지지형상이 데크플레이트 시스템의 최대 하중저항 성능에 미치는 영향은 크지 않은 것으로 조사되었고, 시스템의 파괴모드는 설계의도에 따라 데크플레이트 중앙에서 상부 주철근의 좌굴, 래티스 단부 좌굴, 또는 이들의 조합으로 나타났다.

• 한국지반환경공학회 논문집
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• 제24권2호
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• pp.13-24
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• 2023

Tunnels may undergo a larger or a smaller response compared with the free-field soil. In the pseudo-static procedure, the response of the tunnel is most often characterized by a curve that relates the racking ratio (R) with the flexibility ratio (F), where R represents the ratio of the tunnel response with respect to the free-field vibration and F is the relative stiffness of the tunnel and the surrounding soil. A set of analytical and empirical curves that do not account for the depth and the aspect ratio of the tunnel are typically used in practice. In this study, a series of dynamic analyses are conducted to develop a set of F-R_m relations for use in a frame analysis method. R_m is defined as an adjusted R where the rocking mode of deformation is removed and only the racking deformation is extracted. The numerical model is validated against centrifuge test recordings. The influence of aspect ratio, buried depth of tunnel on results is investigated. The results show that R_m increases with the increase of the buried depth and the aspect ratio. The widely used F-R relations are highlighted to be different compared with the obtained results in this study. Therefore, the updated F-R_m relations with proposed equations are recommended to be used in practice design. The rocking response decreases with either the decrease of the difference of stiffness between surrounding soil and tunnel or the larger aspect ratio of the tunnel section.

• 인간식물환경학회지
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• 제22권5호
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• pp.455-466
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• 2019

This study was carried out to analyze trends in floral products and services through the big data analysis of various social networking services (SNSs) and then to provide objective marketing directions for the floricultural industry. To analyze the big data of SNSs, we used four analytical methods: Cotton Trend (Social Matrix), Naver Big Data Lab, Instagram Big Data Analysis, and YouTube Big Data Analysis. The results of the big data analysis showed that SNS users paid positive attention to flower one-day classes that can satisfy their needs for direct experiences. Consumers of floral products and services had their favorite designs in mind and purchased floral products very actively. The demand for flower items such as bouquets, wreaths, flower baskets, large bouquets, orchids, flower boxes, wedding bouquets, and potted plants was very high, and cut flowers such as roses, tulips, and freesia were most popular as of June 1, 2019. By gender of consumers, females (68%) purchased more flower products through SNSs than males (32%). Consumers preferred mobile devices (90%) for online access compared to personal computers (PCs; 10%) and frequently searched flower-related words from February to May for the past three years from 2016 to 2018. In the aspect of design, they preferred natural style to formal style. In conclusion, future marketing activities in the floricultural industry need to be focused on social networks based on the results of big data analysis of popular SNSs. Florists need to provide consumers with the floricultural products and services that meet the trends and to blend them with their own sensitivity. It is also needed to select SNS media suitable for each gender and age group and to apply effective marketing methods to each target.

• 대한토목학회논문집
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• 제43권2호
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• pp.259-266
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• 2023

글로벌 기후변화로 국내 이상기후는 증가하고 있으며, 이러한 이상기후로 국지성 집중호우 피해와 규모는 증가하는 추세이다. 침수피해를 예방하기 위해서는 강우예보를 통한 시강우데이터를 통해서 선제적인 침수분석 모의결과를 도출하고 즉각적인 의사결정을 통해 홍수대응 방재시설의 활용과 관리를 통한 예방이 필요하다. 그러나, 현재 XPSWMM, GATE2018과 같은 유출 및 침수모델을 이용하는 방법은 전문적인 사용능력과 복잡한 분석절차로 사용에 대한 한계성이 존재한다. CBD 소프트웨어 개발방식을 이용 강우량(단기, 장기) 등의 산정을 통해 홍수대응 방재시설 시뮬레이터 프로토타입 개발하며, 관리자 및 사용자 중심의 인터페이스를 구성하고 GIS데이터 및 가시적 데이터(그래프, 차트 등)를 제공하여 즉각적이고 선제적인 국지성 집중호우 침수대응을 위한 의사결정 및 기초데이터 사용이 가능할 것으로 기대된다.

• 한국지반공학회논문집
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• 제23권8호
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• pp.77-85
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• 2007

본 연구에서는 선정된 부산 신항만 공사 지역의 연약 점토층을 대상으로 비배수전단강도 값을 분석하고 CPT적용을 위한 콘계수의 변화특성 및 영향인자를 비교분석하고자 한다. 이를 위해 다양한 현장시험과 실내시험 결과를 분석하였으며, 현장시험에서 구해진 콘계수와 실내시험에서 얻어진 결과를 토대로 한 이론적인 콘계수와의 비교를 통해 해당 현장에 가장 적합한 이론식을 선정하고자 한다. 본 연구에서 사용된 이론식은 Baligh(1975)와 Yu(1993)의 공동 확장 이론과 Teh and Houlsby(1991)와 Yu 등(2000)의 정적 상태 해석법이 사용되었으며, 공동 확장 해석법이 현장 시험을 통해 측정된 콘계수와 부합하는 결과를 나타내었다.

• Journal of Korea Trade
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• 제26권3호
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• pp.79-101
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• 2022

Purpose - The purpose of this study is to analyze and compare the international competitiveness of digital service trade between Korea and China and to help enhance the competitive advantage of digital service trade between the two countries. Design/methodology - This paper designs and establishes a comprehensive evaluation system for the international competitiveness of the Korea-China digital service trade. By using the analytical methods of combining theory and demonstration through qualitative and quantitative analysis, this paper makes a concrete and complete theoretical deconstruction and empirical measurement of its international competitiveness from the two levels of overall competitiveness and departmental competitiveness. At the same time, the study also analyzes the competitive advantages and comparative disadvantages of the two countries. Findings - It is found that South Korea has a strong competitive advantage in the sector competitiveness of digital service trade, and the export structure is reasonable and balanced, but the deficit pattern affects the overall competitiveness. China has a strong competitive advantage in the overall competitiveness of the digital service trade. However, the structural imbalance in the export sector weakens the competitiveness of the sector. Both Korea and China have the space advantage and competitive potential to enhance international competitiveness in terms of development trends. Originality/value - This paper takes the lead in solving the pain point of the relative lack of similar research topics. It demonstrates the evolution process, development trends, and structural characteristics of the digital service trade. A new combination of competitive power research methods is innovated, and a comprehensive evaluation system is established. The above innovation points show the academic theoretical value and practical application value of this study.

• 한국프랜차이즈경영연구
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• 제8권1호
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• pp.31-41
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• 2017

Purpose - As the domestic coffee market is rapidly growing and competition is intensifying, coffee shops need to establish a marketing strategy that grasps the needs and desires of consumers in order to secure a competitive advantage in terms of survival. From this point of view, this study suggests what choice attributes consumers consider when visiting coffee shops, and analyzes the effect of customer choice attributes on franchise and private coffee shops using fsQCA. Research design, data, and methodology - In the present study, we tried to understand the effect of the combination of choice attribute on satisfaction by the type of coffee shop based on the complex system theory, while studying the existing coffee shop choice attribute focuses on the causal relationship. FsQCA is a complementary analytical method between quantitative and qualitative research, and is a method for effectively analyzing the complex combination of causal variables. Result - The results of the study are as follows. First, cleanliness was found to be the most important factor in determining coffee quality, which is the most important factor affecting customer satisfaction. Second, customers who prefer franchise coffee shops seem to be most concerned about atmosphere, menu, cleanliness and price. On the other hand, customers who prefer private coffee shops consider image the most important. Conclusions - The implications of this study are as follows. Overall, coffee shops should manage cleanliness basically regardless of the type of store, but they should manage the choice attributes differently depending on the type of coffee shop. Franchise coffee shops will be able to increase the level of store satisfaction by systematically managing the store atmosphere, menu, cleanliness, and price according to the manual using the advantages of the franchise system. On the other hand, unlike the franchise coffee shops, private coffee shops can operate autonomous stores, so customers can use various marketing mixes to enhance their store image.

• Smart Structures and Systems
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• 제31권3호
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• pp.283-299
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• 2023

Structural stability of floating platforms has long since been a crucial issue in the field of marine engineering. Excessive motions would not only deteriorate the operating conditions but also seriously impact the safety, service life, and production efficiency. In recent decades, several control devices have been proposed to reduce unwanted motions, and an attractive one is the tuned heave plate (THP). However, the THP system may reduce or even lose its effectiveness when it is mistuned due to the shift of dominant wave frequency. In the present study, a novel adaptive tuned heave plate (ATHP) is proposed based on inerter by adjusting its inertance, which allows to overcome the limitation of the conventional THP and realize adaptations to the dominant wave frequencies in real time. Specifically, the analytical model of a representative semisubmersible platform (SSP) equipped with an ATHP is created, and the equations of motion are formulated accordingly. Two optimization strategies (i.e., J₁ and J₂ optimizations) are developed to determine the optimum design parameters of ATHP. The control effectiveness of the optimized ATHP is then examined in the frequency domain by comparing to those without control and controlled by the conventional THP. Moreover, parametric analyses are systematically performed to evaluate the influences of the pre-specified frequency ratio, damping ratio, heave plate sizes, peak periods and wave heights on the performance of ATHP. Furthermore, a Simulink model is also developed to examine the control performance of ATHP in the time domain. It is demonstrated that the proposed ATHP could adaptively adjust the optimum inertance-to-mass ratio by tracking the dominant wave frequencies in real time, and the proposed system shows better control performance than the conventional THP.