• 디지털산업정보학회논문지
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• 제8권1호
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• pp.47-53
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• 2012

Sensor networks and car networks that have different structure from that of conventional TCP/IP network require extreme network environment due to frequent change of connectivity. Because such extreme network environment has characteristics like unreliable link connectivity, long delay time, asymmetrical data transfer rate, and high error rate, etc., it is difficult to perform normally with the conventional TCP/P-based routing. DTNs (delay and disruption tolerant network) was designed to support data transfer in extreme network environment with long delay time and no guarantee for continuous connectivity between terminals. This study suggests an algorithm that limits the maximum number of copying transferred message to L by improving the spray and wait routing protocol, which is one of the conventional DTNs routing protocols, and using the azimuth and density data of the mobile nods. The suggested algorithm was examined by using ONE, a DTNs simulator. As a result, it could reduce the delay time and overhead of unnecessary packets compared to the conventional spray and wait routing protocol.

• 대한산업공학회지
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• 제37권3호
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• pp.229-233
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• 2011

The existing approaches for analyzing the data service capacity of CDMA2000 1X EV-DO (Evolution-Data Only) systems have focused on deriving the maximum number of active customers assuming that the data rates provided to the customers can be determined beforehand. However, we have seen that through real experiment, the data rates actually provided to the customers adaptively change according to the number of active customers. In this paper, we propose new capacity analysis model considering the data rate adaptation. Numerical examples are also presented to obtain the maximum input traffic rates for various values of the length of data burst and the required mean delay bound.

• 디지털산업정보학회논문지
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• 제13권1호
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• pp.79-85
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• 2017

Vehicular ad-hoc networks (VANETs) cause link disconnection problems due to the rapid speed and the frequent moving direction change of vehicles. Link disconnection in vehicle-to-vehicle communication is an important issue that must be solved because it decreases the reliability of packet forwarding. From the characteristics of VANETs, greedy forwarding protocols using the position information based on the inter-vehicle distance have gained attention. However, greedy forwarding protocols do not perform well in the urban environment where the direction of the vehicle changes greatly. It is because greedy forwarding protocols select the neighbor vehicle that is closest to the destination vehicle as the next transmission vehicle. In this paper, we propose a greedy anycast forwarding (GAF) protocol to improve the reliability of the inter-vehicle communication. The proposed GAF protocol combines the greedy forwarding scheme and the anycast forwarding method. Simulation results show that the GAF protocol can provide a better packet delivery rate than existing greedy forwarding protocols.

• International Journal of Computer Science & Network Security
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• 제21권8호
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• pp.43-50
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• 2021

For the implementation of innovative products or services companies use different innovation strategies, in particular, outsourcing is quite widespread, given the high level of specialization and professionalism of companies that provide such services. The aim of this article was to evaluate the link between outsourcing of innovative activities and indicators of companies' efficiency. The methodology of the research includes the methods of correlation analysis and regression analysis to reveal the correlation between the use of outsourcing of innovative products and services and the turnover of the EU enterprises. The results show a high level of innovative activity of EU enterprises (50.3% innovatively active). Innovative business processes are the most widespread form of innovation activity (41% of enterprises implement business processes, and the indicator is higher than 41% in the most developed EU countries). The turnover of enterprises with new or substantially improved products was found to grow by 10.92% for the period 2016-2018. The correlation analysis shows weak direct links between the indicator of turnover growth and the number of enterprises that have independently implemented innovations, or have implemented innovations jointly with third-party companies, or using outsourcing services. The highest level of direct connection was found between the growth of turnover of enterprises that launched a new product for the market and the growth of the number of enterprises that implemented innovations with the involvement of organizations (correlation 0.273). Based on the regression analysis it was found that with a 1% change in the growth rate of the number of innovation-active enterprises, the growth rate of turnover from new or improved products increased by 5.67%. At the same time, with a 1% change in the growth rate of the number of enterprises that implement innovation through outsourcing, the growth rate of turnover from new or improved products will increase by 7.15%.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2006년도 추계학술발표대회 논문집
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• pp.177-178
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• 2006

This plan is for a different type of welfare facilities devised by analyzing problems with existing welfare centers and focusing on connection with residents and link between culture and welfare and among generations. In terms of re-development plan of Youngsun-2-dong, Youngdo-gu, Busan and the neighborhood under this plan, Youngsun-dong, Youngdo-gu is one of the densely populated districts of the aged, with lower growth rate and poor housing and welfare facilities. However, the district has a blessed natural environment and historical site of cultural relics of the Neolithic Age as well as growth potential as a logistics center with broader network of roads linking with Bukhang Bridge when Namhang Bridge construction is complete, showing the aspiration for change toward hi-tech maritime city in the 21st century of Youngdo-gu. This plan is expected to promote unity between the old and children, protection from social marginalization, and re-socialization education and set the stage for participation and solidarity of residents in the community.

• Computers and Concrete
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• 제30권3호
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• pp.185-196
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• 2022

In this paper, the dynamic characteristics of a composite cylindrical beam made of a mechanism of carbon dioxide absorption coated on the tube core are investigated based on the classical beam theory coupled with the modified couple stress theory. The composite tube structures are assumed to be uniform along the tube length, and the energy method regarding the Hamilton principle is utilized for generating the governing equations. A powerful numerical solution, the generalized differential quadrature method (GDQM), is employed to solve the differential equations. The carbon dioxide trapping mechanism is a composite consisting of a polyacrylonitrile substrate and a cross-link polydimethylsiloxane gutter layer. Methacrylate, poly (ethylene glycol), methyl ether methacrylate, and three pedant methacrylates are all taken into account as potential mechanisms for capturing carbon dioxide. The application of the present study is helpful in the design and production of microelectromechanical systems (MEMS) and the different valuable parameters, such as the length-scale parameter, rate of section change, aspect ratio, etc., are presented in detail.

• 한국정밀공학회지
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• 제14권7호
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• pp.137-143
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• 1997

In this study, handling simulation of a passenger car is carried out to see the effects of suspension compliance, roll stabilizef bar and chassis flexibility. The front suspension of the car is a MacPherson strut type and the rear suspension is a multi-link type. The following five DADS models are constructed and compared to verify the effects of suspension compliance and chassis flexibility during lane change. (1) Vdhicle model without hard point compliance and stabilizer, (2) Vehicle model with hard point compoiance, (3) Vehicle model with hard point compliance and stabilizer, (4) Vehicle model with hard point compoiance, stabilizer, and one vibration mode of the chaxxis. (5) Vehicle model with hard point compliance, stabilizer, and three vibration modes of the chassis. The result shows that hard point compliance and stabilizer are significant in roll angle, and the flexibility of the chassis affects the yaw angle and yaw rate.

• 전자공학회논문지S
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• 제35S권9호
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• pp.28-34
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• 1998

본 논문에서는 ATM망에서 ABR 서비스를 효율적으로 제공하기 위해 ABR 소스가 전송하는 데이터 전송률에 기반한 폭주 제어 알고리즘을 제안한다. 제안된 방법은 망의 가용 대역폭에 따라 각 소스에 할당될 대역폭을 계산하여 RM 셀의 ER 필드에 넣어 전송한다. ATM 스위치는 ABR 소스의 단위 시간당 전송하는 셀 전송률의 변화율에 기반하여 대역폭을 계산한다. 제안된 방법은 각 소서의 전송률 변화에 따라 망의 가용 대역폭을 활용하기 때문에 각 소스의 상태에 따라 동적으로 대역폭을 할당할 수 있고 또한 스위치가 소스의 전송률 변화에 빠르게 전송한다. 본 논문에서 제안한 방법과 기존의 동적 폭주 제어 방법에 대한 시뮬레이션 결과는 제안된 방법이 기존의 방법보다 소스의 상태에 능동적으로 대처하며 링크의 이용률이 향상됨을 보여준다.

• Steel and Composite Structures
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• 제19권5호
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• pp.1167-1184
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• 2015

Despite considerable life casualty and financial loss resulting from past earthquakes, many existing steel buildings are still seismically vulnerable as they have no lateral resistance or at least need some sort of retrofitting. Passive control methods with decreasing seismic demand and increasing ductility reduce rate of vulnerability of structures against earthquakes. One of the most effective and practical passive control methods is to use a shear panel system working as a ductile fuse in the structure. The shear Panel System, SPS, is located vertically between apex of two chevron braces and the flange of the floor beam. Seismic energy is highly dissipated through shear yielding of shear panel web while other elements of the structure remain almost elastic. In this paper, lateral behavior and related benefits of this system with narrow-flange link beams is experimentally investigated in chevron braced simple steel frames. For this purpose, five specimens with IPE (narrow-flange I section) shear panels were examined. All of the specimens showed high ductility and dissipated almost all input energy imposed to the structure. For example, maximum SPS shear distortion of 0.128-0.156 rad, overall ductility of 5.3-7.2, response modification factor of 7.1-11.2, and finally maximum equivalent viscous damping ratio of 35.5-40.2% in the last loading cycle corresponding to an average damping ratio of 26.7-30.6% were obtained. It was also shown that the beam, columns and braces remained elastic as expected. Considering this fact, by just changing the probably damaged shear panel pieces after earthquake, the structure can still be continuously used as another benefit of this proposed retrofitting system without the need to change the floor beam.

• 유통과학연구
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• 제11권10호
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• pp.55-62
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• 2013

Purpose - The purpose of this study is to suggest a risk factor that significantly explains foreign currency risk premia. In recent years, some studies have found that the performance of the simultaneous consumption risk model improves considerably when tested on foreign currency portfolios, which are constructed based on the international interest rates differentials. However, this paper focuses on the long-run consumption risk factor. In our empirical research, we found that the real excess returns of high interest rate currency portfolios depreciate on average, when the future American long-run consumption growth rate appears low. This makes the high interest rate currency portfolios have relatively high risk premia. Meanwhile, the real excess returns of low interest rate currency portfolios appreciate on average, under the same conditions, which results in relatively low risk premia for these portfolios. Therefore, this long-run consumption risk factor might explain why low interest rate currencies do not appreciate as much as the interest rate differential, and why high interest rate currencies do not depreciate as much as the interest rate differential. Research design, data, methodology - In our explanation, we provide new evidence on the success of long-run consumption risks in currency risk premia by focusing on the long-run consumption risks borne by American representative investors. To uncover the hidden link between exchange rates and long-run consumption growth, we set the eight currency portfolios as our basic assets, which have been built based on the foreign interest rates of eighty countries. As these eight currency portfolios are rebalanced every year, the first group always contains the lowest interest rate currencies, and the last group contains the highest interest rate currencies. Against these basic eight currency portfolios, we estimate the long-run consumption risk model. We use recursive utility framework and the stochastic discount factor that depends on the present value of expected future consumption growth rates. We find that our model is optimized in the two-year period of constructing the durable consumption expectation factor. Our main results surprisingly surpass the performance of the existing benchmark simultaneous consumption model in terms of R², relatively risk aversion coefficient γ, and p-value of J-test. Results - The performance of our model is superior. R², relatively risk aversion coefficient γ, and p-value of J-test of our long-run durable consumption model are 90%, 93%, and 65.5%, respectively, while those of EZ-DCAPM are 87%, 113%, and 62.8%, respectively. Thus, we can speculate that the risk premia in foreign currency markets have been determined by the long-run consumption risk. Conclusions - The aggregate long-run consumption growth risk explains a large part of the average change in the real excess returns of foreign currency portfolios. The real excess returns of high interest rate currency portfolios depreciate on average when American long-run consumption growth rate is low, and the real excess returns of low interest rate currency portfolios appreciate under the same conditions. Thus, the low interest rate currency portfolios allow investors to hedge against aggregate long-run consumption growth risk.