• Journal of KIISE:Computer Systems and Theory
• /
• v.32 no.10
• /
• pp.530-540
• /
• 2005

Virtual colonoscopy is an easy and fast method to reconstruct the shape of colon and diagnose tumors inside the colon based on computed tomography images. This is a non-invasive method, which resolves weak points of previous invasive methods. The path for virtual colonoscopy should be generated rapidly and accurately for clinical examination. However, previous methods are computationally expensive because the data structure such as distance map should be constructed in the preprocessing and positions of all the points of the path needs to be calculated. In this paper, we propose the automatic path generation method based on visibility to decrease path generation time. The proposed method does not require preprocessing and generates small number of control points representing the Path instead of all points to generate the path rapidly. Also, our method generates the path based on visibility so that a virtual camera moves smoothly and a comfortable and accurate path is calculated for virtual navigation. Also, our method can be used for general virtual navigation of various kinds of pipes.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.11
• /
• pp.797-809
• /
• 2006

To support the QoS streams for large scale clients, the internal resources of VOD servers should be utilized based on the characteristics of the streaming media service. Among the various resources in the server, the main memory is used for the buffer space to the media data loaded from the disks and the buffer hit ratio has a great impact upon the server performance. However, if the buffer data with high hit ratio are replaced for the new media data as a result of the number of clients and the required movie titles are increased, the negative impact on the scalability of server performance is occurred. To address this problem, the buffer replacement policy considers the intrinsic characteristics of the streaming media such as the sequential access to large volume data and the highly disproportionate preference to specific movies. In this paper, the preference-based segment buffer replacement policy is proposed in the cluster-based VOD server to exploit the characteristics of the streaming media. Since the proposed method reflects both the temporal locality by the clients' preference and the spatial locality by the sequential access to media data, the buffer hit ratio would be improved as compared to the existing buffer replacement policy. The enhanced buffer hit ratio causes the fact that the performance scalability of the cluster-based VOD server is linearly improved as the number of cluster nodes is increased.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.11
• /
• pp.820-829
• /
• 2006

Wireless sensor networks consisting of hundreds to thousands of nodes are expected to be increasingly deployed in coming years, as they enable reliable monitoring and analysis of physical worlds. These networks have unique features that are very different from traditional networks, e.g., the numerous numbers of nodes, limitation in power, processing, and memory. Due to these unique features of wireless sensor networks, sensor data management including querying becomes a challenging problem. Furthermore, due to wide popularization of the Internet and its facility in use, it is generally accepted that an unattended network can be efficiently managed and monitored over the Internet. In particular, in order to more efficiently query and manage data in a sensor network. in this paper, the architecture of a sensor gateway including web-based query server is presented and its implementation detail is illustrated. The presented web-based gateway is largely divided into two important parts: Internet part and sensor network part. The sensor network part plays an important role of handling a variety of sensor networks, including flat or hierarchical network architecture, by using internally layered architecture for efficiently querying and managing data in a sensor network. In addition, the Internet part provides a modular gateway function for favorable exchange between the sensor network and Internet.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.8
• /
• pp.554-561
• /
• 2006

In recent years, as SoC design research is actively conducted, a large number of IPs are included in a system. Various bus protocols and bus architectures are designed to increase IP reusability. Among them, the AMBA AHB became a de facto standard although it is somewhat inadequate for a large scale SoC. We proposed SNP and SNA, high performance on-chip-bus protocol and architecture, respectively, to solve the problem of the conventional shared buses. However, it seems to be imperative that the new on-chip-bus system support AMBA-compatible IPs for a while since there are a lot of IPs with AMBA interface. In this paper, we propose an extended SNP specification and a corresponding SNA component to support ABMA-compatible IPs used in SNA - based system. We extend the phase of the SNP by 1 bit to add new 8 phases to support communication based on AMBA protocol without penalty of elongated cycle latency. The ARB-to -XSNP converter translates the protocol between AHB and SNP to attach AMBA -compatible IPs to SNA based system. We show that AMBA IPs can communicate through SNP without any degradation of performance using the extended SNP and AHB - to- XSNP converter.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.8
• /
• pp.536-546
• /
• 2006

Painterly animation is a method that expresses painterly images with a hand-painted appearance from a video, and the most crucial element for it is the temporal coherence of brush strokes between frames. A motion map is proposed in this paper as a solution to the issue of maintaining the temporal coherence in the brush strokes between the frames. A motion map is the region that frame-to-frame motions have occurred. Namely, this map refers to the region frame-to-frame edges move by the motion information with the motion occurred edges as a starting point. In this paper, we employ the optical flow method and block-based method to estimate the motion information. The method that yielded the biggest PSNR using the motion information (the directions and magnitudes) acquired by various methods of motion estimation has been chosen as the final motion information to form a motion map. The created motion map determine the part of the frame that should be re-painted. In order to express painterly images with a hand- painted appearance and maintain the temporal coherence of brush strokes, the motion information was applied to only the strong edges that determine the directions of the brush strokes. Also, this paper seek to reduce the flickering phenomenon between the frames by using the multiple exposure method and the difference map created by the difference between images of the source and the canvas. Maintenance of the coherence in the direction of the brush strokes was also attempted by a local gradient interpolation to maintain the structural coherence.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.1_2
• /
• pp.79-91
• /
• 2006

The intelligent disk can improve the overall performance of the I/O subsystem by processing the I/O operations in the disk side. At present time, however, realizing the intelligent disk seems to be impossible because of the limitation of the I/O subsystem and the lack of the backward compatibility with the traditional I/O interface scheme. In this paper, we proposed new model for the intelligent disk that dynamically optimizes the I/O subsystem using the information that is only related to the physical sector. In this way, the proposed model does not break the compatibility with the traditional I/O interface scheme. For these works, the boosting algorithm that upgrades a weak learner by repeating teaming is used. If the last learner classifies a recent I/O workload as the multimedia workload, the disk reads more sectors. Also, by embedding this functionality as a firmware or a embedded OS within the disk, the overall I/O subsystem can be operated more efficiently without the additional workload.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.373-378
• /
• 2001

In order to analyze the problems and improvement methods in the quality management of domestic apartment construction projects, this study derived the four barrier factors through relevant literature survey and interviews with construction practitioners. Among these four factors, which are 1) policies and regulations, 2) technologies, 3) human and organization, and 4) other miscellaneous aspects, the human and organization factor is the main focus of this survey and it was decomposed into perception, management system, education, and system on quality management according to the Taguchi's S/N theory to survey existing problems and suggest improvement methods for them. The survey on the quality perception showed that all the members need to cooperate actively, and CEO and chief construction managers should recognize the quality as the highest priority and act by themselves accordingly. The survey on the quality management showed that they need to reform their business process to reduce redundant tasks and miscommunications among participants. Quality education should be provided in a way that people at different management level can be educated differently with close relation to their practices. Quality systems should help corrective actions against quality problems at construction fields. Also with clear quality management implantation polices and objectives, the quality system should be established in order to support better communication among project stakeholders.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.18 no.2
• /
• pp.153-159
• /
• 2012

This study gives the vertical motion analysis in multi-directional irregular waves using a commercial code(MAXSURF v.16) based on linear strip theory for a training ship. To verify the commercial code prior to the analysis, we guarantees the reliability of this paper's results using the commercial code by comparing with the results(Flokstra, 1974) of same hull and experimental conditions on a Panamax container. The analysis conditions are Beaufort wind scale No. 5($\bar{T}=5.46$, $H_{1/3}=2m$) based on ITTC wave spectrum, encounter angle Head & bow seas($150^{\circ}$) and Froude number Fn=0.257. Finally, we calculates heave RAO, pitch RAO and obtains the result of ship's response spectra for heave and pitch motions. In the motion response spectrum under the multi-directional irregular waves, heave motion reacts slightly high in short-crested waves and pitch motion reacts high in long-crested waves.

• Journal of East-West Nursing Research
• /
• v.10 no.1
• /
• pp.27-40
• /
• 2004

Relapse is one of the most series problems in alcoholics treatment. Previous studies have shown that significant proportions of treated alcoholics show an early relapse and go through a chronic phase. It is necessity to find more effective relapse prevention program. The Purpose of this study was to develop a relapse prevention program that emphasis on group activities using various action methods. Previous studies revealed that there was no effective therapeutic strategy to prevent relapse and proposed that action methods were more practical ways to be able ti cope with high-risk situation than verbal methods such as discussions and lectures. The special attempt of this program was the application of various actions methods and the integration of many psychosocial therapeutic strategies as compared with many relapse prevention programs. The theoretical framework of this relapse prevention program was based on mainly the Marlatt's Relapse Prevention model and Prochescha and DiClemente's Transtheoretical model. This Program consists of eight structure sessions. Every session has three phase: Warm-up phase, action phase, and sharing phase as sociodrama structure. Sociodrama is based on many of the principles of adult learning. And sociodrama looks at how groups work through an understanding of systems and role theory. Therefore, in working with a group a therapist might explore with them the roles that people play, roles that are missing at present such a visionary and how people can develop new roles or new ways of playing existing roles. The researchers explained the purpose of this study to all participants after their agreement to participate. Voluntary informed consent was obtained from all participants. Every session allows participants to recognize personal specific high-risk situation and to examine possible coping behaviors creatively. Multiple solutions can be proposed, tested and evaluated dramatically, giving new insights or breakthroughs in thinking. This is vital for the initiation of change, and if appropriate, expanding new role development. The first two sessions aim at understanding of relapse process and recognize of high-risk situations focused on orientation about action methods. The next four sessions deal with high-risk situations. The last two sessions give participants opportunities to venture new life-styles. The methods and approaches used in this program utilized as a tool to explore and practice possible coping strategies. and this program can contribute to prevent relapse episode if tune with the particular high-risk situation by using active practices in safe environment.

• The KSFM Journal of Fluid Machinery
• /
• v.18 no.6
• /
• pp.63-70
• /
• 2015

This paper proposes a novel airfoil named "KA2" for the blade of the wind turbine systems. Dynamic loads characteristics are analyzed and compared using aerodynamic data of ten airfoils including the proposed airfoil. The blade is divided into the sixteen elements in the longitudinal direction of the blade for applying the Blade Element Method Theory (BEMT) method, and in each element, torque, thrust, and pitching moment are calculated using turbulent time varying wind speed and aerodynamic data of each wing. Additionally, each force and torque is accumulated in the whole region of the blade for the estimation of representative values. The magnitude of such forces is comparatively analyzed for different airfoils. The angle of attack is constant below the rated wind speed due to the fact that the tip speed ratio is kept at the constant value, and it increases in the region of over rated wind speed as the tip speed ratio decreasing with constant rated rpm and increasing wind speed. Such increase in the angle of attack causes the changes of the force acting on the airfoil with different characteristics of lift and drag in the stall region of each different airfoil. Even though the mean wind speed is in the rated speed in a given time, because of the turbulence, it has either the over rated or under rated speed most of the time. Furthermore, the dynamic properties of each force are analyzed in this rated wind speed in order to objectively understand the dynamic properties of the blades which are designed based on the different airfoils. These dynamic properties are also compared by the standard deviation of time varying characteristics. Moreover, the output characteristics of the wind turbine are investigated with different airfoils and wind speeds. Based on these investigations, it was revealed that the proposed airfoil (KA2) is well applicable to the blade with passive pitch control system.