• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.1
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• pp.31-42
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• 2023

As computer performance is leveled upward, the use of IoT systems is gradually expanding. Although IoT systems are used in many fields, it is true that it is difficult to build a safe system due to performance limitations. To overcome these limitations, many researchers have proposed numerous protocols to improve security issues. Among them, Azrour et al. except. We proposed a new efficient and secure authentication protocol for remote healthcare systems in a cloud-based IoT environment, and claimed that the new protocol could solve the security vulnerabilities of the existing protocols and was more efficient. However, in this paper, through the security analysis of the remote healthcare system in the cloud-based IoT environment proposed by Azrour et al., the protocol of this system was found to be vulnerable to Masquerade attack, Lack of Perfect Forward Secrecy, Off-line password guessing attack, and Replay attack.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1934-1935
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• 2011

In order for a service robot to perform several tasks, basically autonomous navigation technique such as localization, mapping, and path planning is required. The localization (estimation robot's pose) is fundamental ability for service robot to navigate autonomously. In this paper, we propose a new system for point pattern matching based visual global localization using spot lightings in ceiling. The proposed algorithm us suitable for system that demands high accuracy and fast update rate such a guide robot in the exhibition. A single camera looking upward direction (called ceiling vision system) is mounted on the head of the mobile robot and image features such as lightings are detected and tracked through the image sequence. For detecting more spot lightings, we choose wide FOV lens, and inevitably there is serious image distortion. But by applying correction calculation only for the position of spot lightings not whole image pixels, we can decrease the processing time. And then using point pattern matching and least square estimation, finally we can get the precise position and orientation of the mobile robot. Experimental results demonstrate the accuracy and update rate of the proposed algorithm in real environments.

• Architectural research
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• v.19 no.1
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• pp.7-11
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• 2017

Energy consumption in university building has steadily increased over the last decade, and a strong upward trend in recent years. This study was undertaken to analyze the relationship between energy consumption and their affecting factors, six academic buildings were considered. The factors limited to heating and cooling, which is the main end use (nearly 60 per cent of total energy consumption in university buildings), encompassing system and operating schedules (user activity) and area use. To understand how to building is used, operated and managed, walk-through assessment was conducted as well as interview with university staff. The results show that the energy consumption of the humanities building was somewhat smaller than the consumption of the science and engineering building, and its range was from $31.26kgoe/m^2$ to $23.52kgoe/m^2$, depending on heating and cooling system and area use. And the energy consumption of the science and engineering building was related to operating schedules (user activity) as well as laboratory equipment characteristics. More analysis on a larger number of buildings is required in the future, including building form and material performance level to generalize the significant factors influencing building energy consumption.

• Solar Energy
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• v.18 no.1
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• pp.99-109
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• 1998

The study on ice thermal storage system is to improve total system performance in actual air-conditioning facilities. To attain the high efficiencies in ice thermal storage system, the improvement of thermal stratification is essential, therfore the process flow must be piston flow in thermal storage tank. Ice packing factor is better on condition that the inflowing temperature is low, the flow direction in the thermal storage is upward and the cylindericalthermal storage type is used. This result shows that the cylinderical ice storage tank has better storage capacity than the rectangular type in case of the same porocity.

• IE interfaces
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• v.18 no.3
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• pp.234-246
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• 2005

A silicon wafer is a highly customized product made to the individual order varying its electrical and physical characteristics. Therefore, it has distinctive supply chain structure that is different from highly standardized commodity product. For high-volume/high-standardization product, it is general that a main stream of information flow initiated by the production planning of the manufacturers is usually directed to push both ways in a supply chain: upstream to the suppliers and downstream to the customers. Contrastingly, for low-volume/high-customization product, the information flow triggered by the fluctuating customer demand usually propagates upward to the suppliers through the manufacturers. Furthermore, for R &D based hi-technology product like silicon wafer, the interactive information feedback mechanism between manufacturer and customer, which is essential to the new product development process, is to be embedded in the supply chain. This article is a case study of supply chain management system of LG Siltron, a major Korean silicon wafer manufacturer. The SCM system entails special information structure fitting well typical high-variety/high-customization product, and also gives application possibilities to the R&D based high-technology product made to the individual customer order.

• Journal of Korea Foundry Society
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• v.17 no.1
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• pp.93-99
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• 1997

A possibility of production of aluminium matrix composites by using the lost foam process was investigated. Silicon carbide particles, graphite particles, and stainless steel wires were used as reinforcement materials. The reinforcement materials were introduced to the polystyrene to form patterns via injection molding process. The results obtained from this experiment can be summarized as follows. In Al/SiCp system, the particles with the radius of $100{\mu}m$ and over were entrapped in the matrix in the case of upward freezing of which solidification direction was opposite to floating direction of the particles. And few particles were entrapped in the matrix in downward freezing. In Al/graphite system, almost no particles were entrapped in the matrix except the area chill attatched. When the thickness of polystyrene slice was 4mm in Al/stainless steel wire system, the floating tendency of fibers was observed to increase as the distance from the ingate was increased.

• Journal of Sasang Constitutional Medicine
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• v.20 no.2
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• pp.53-57
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• 2008

1. Objectives When we give Jowiseungcheong-tang to Taeumin patients, analyzing a change of their autonomic nervous system. It is measured by the heart rate variability(HRV) analyzer. 2. Methods We give Jowiseungcheong-tang to ten Taeumin patients for three days and examine the HRV at first time and three days later. 3. Results and Conclusions We compared two HRV results. The value of RRNN(average of normal RR intervals), SDNN(the standard deviation of all normal RR intervals), RMSSD(the root mean square of successive differences between the normal heart beats) have a downward tendency. Norm HF(normalized high frequency power) have a upward tendency. norm LF (normalized low frequency power) and LHR(LF/HF ratio) have a downward tendency. It means hypofunction of autonomic nervous system. But all results are not significant. We think that restudy is needed with more patients and longer periods afterward.

• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.42-47
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• 2009

The propagation of an intense laser pulse through an upward density-gradient plasma in a self-modulated laser wakefield acceleration (SM-LWFA) is investigated by using particle-in-cell (PIC) simulations. In the fully relativistic and kinetic PIC simulations, the relativistic and kinetic effects including Landau damping enhance the electron dephasing. This electron dephasing is the most important factor for limiting the energy of accelerated electrons. However, the electron dephasing, which is enhanced by relativistic and kinetic effects in the homogeneous plasma, can be forestalled through the detuning process arising from the longitudinal density gradient. Simulation results show that the detuning process can effectively maintain the coherence of the laser wake wave in the spatiotemporal wakefield pattern, hence considerable energy enhancement is achievable. The spatiotemporal profiles are analyzed for the detailed study on the relativistic and kinetic effects. In this paper, the optimum slope of the density gradient for increasing electron energy is presented for various laser intensities.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.737-744
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• 2021

An investigation is conducted to study a solid-liquid mixture vertically upward hydraulic transport of solid particles by non-Newtonian fluids in the Mud system. Rheology of particulate suspensions in viscoelastic fluids is of importance in many applications such as particle removal from surfaces, transport of proppants in fractured reservoir and cleaning of drilling holes, etc. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. Annular velocities varied from 0.4 m/s to 1.2 m/s. The mud systems which were utilized included aqueous solution of sodium carboxymethyl cellulose (CMC) solutions. Main parameters considered in the study were inner-pipe rotary speed, fluid flow regime and particle injection rate. Solid volumetric concentration and pressure drops were measured for the various parameters such as inclination angle, flow rate, and rotational speed of inner cylinder.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.4
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• pp.101-109
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• 2008

Automated rainfall warning system is a facility to prevent casualties who were recreating in the down stream region with operating lead broadcasting or signaling warning automatically when torrential rainfall occurs in mountainous area. But standard of conventional warning does not consider the characteristics of basin, and warning signal. Evacuation signal 1 and evacuation signal 2 are uniformly signaled when the 10minute moving total of observed rainfall is higher than 4 mm, 6 mm, and 8 mm respectively. therefore, local governments and relative agencies had re-established the standard of warning by analyzing the risk water level, critical discharge and reference rainfall, which are considering the characteristics of basin. In this study the standard of conventional and re-established warning of weolseong basin, which is available to acquire a real rainfall. There are analyzed by considering the risk water level, critcal discharge and reference rainfall. Also this study compares rainfall of conventional and re-established warning standard and indentifies problems by analyzing adequacy of rainfall estimation for warning and proposes alternative. The standard of conventional warning which investigates with the converted rainfall(unit of a minute) issued too many alarm. The re-established standard upward has the necessity which will be regulated about the alarm announcement number of times. Considers the safety, upward regulation of alarm standard rainfall is a necessity which will be prudent.