• Journal of Computing Science and Engineering
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• v.4 no.3
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• pp.189-206
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• 2010

It is generally accepted that dynamic voltage scaling (DVS) is one of the most effective techniques of energy minimization for real-time applications in embedded system design. The effectiveness comes from the fact that the amount of energy consumption is quadractically proportional to the voltage applied to the processor. The penalty is the execution delay, which is linearly and inversely proportional to the voltage. According to the granularity of tasks to which voltage scaling is applied, the DVS problem is divided into two subproblems: inter-task DVS problem, in which the determination of the voltage is carried out on a task-by-task basis and the voltage assigned to the task is unchanged during the whole execution of the task, and intra-task DVS problem, in which the operating voltage of a task is dynamically adjusted according to the execution behavior to reflect the changes of the required number of cycles to finish the task before the deadline. Frequent voltage transitions may cause an adverse effect on energy minimization due to the increase of the overhead of transition time and energy. In addition, DVS needs to be carefully applied so that the dynamically varying chip temperature should not exceed a certain threshold because a drastic increase of chip temperature is highly likely to cause system function failure. This paper reviews representative works on the theoretical solutions to DVS problems regarding inter-task DVS, intra-task DVS, voltage transition, and thermal-aware DVS.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.2
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• pp.203-213
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• 2001

The image and impression characteristics of the consumer electronic products have become an important factor in purchasing decisions. This study aims to analyze and interpret the image and impression characteristics based on the consumer preference survey. The survey consisted of two parts. First part was to measure the predetermined 52 design variables that can represent the design variables of the products. In the second part, 60 subjects were requested to evaluate 36 audio/video electronic products on 25 different image attributes such as luxuriousness, attractiveness, and granularity. In this study, empirical data from the survey were analyzed through various multivariate analysis and ANOVA analysis. Additionally, this study suggested a statistical procedure that can be applied to select and/or screen critical design variables. It is expected that the results of this study can provide practical information to the designers of consumer electronic products.

• Journal of KIISE
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• v.42 no.9
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• pp.1071-1077
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• 2015

In this paper, we adopt PCM (phase-change memory) as a virtual memory swap device and present a new page replacement policy that considers the characteristics of PCM. Specifically, we aim to reduce the write traffic to PCM by considering the dirtiness of pages when making a replacement decision. The proposed policy tracks the dirtiness of a page at the granularity of a sub-page and replaces the least dirty page among the pages not recently used. Experimental results show that the proposed policy reduces the amount of data written to PCM by 22.9% on average and up to 73.7% compared to CLOCK. It also extends the lifespan of PCM by 49.0% and reduces the energy consumption of PCM by 3.0% on average.

• Journal of KIISE:Software and Applications
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• v.27 no.8
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• pp.795-803
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• 2000

This paper presents a shared data decomposition model for improving concurrency in multi-user, distributed software developments. In our model, the target software system is decomposed into the independent components based on project roles to be distributed over clients. The distributed components are decomposed into view objects and core objects to replicate only view objects in a distributed collaboration session. The core objects are kept in only one client and the locking is used to prevent inconsistencies. The grain size of a lock is a role instead of a class which is commonly used as the locking granularity in the existing systems. The experimental result shows that our model reduces response time by 12${\sim}$18% and gives good scalability.

• The Transactions of the Korea Information Processing Society
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• v.3 no.4
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• pp.834-845
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• 1996

Two problems can be happened when we construct Integrated Project Support Environment for construction of software integration environment. The first is a problem about granularity of tool. Problems about interface of tools after combination phase which combine many functions into one and when we use some function of tool with other tools, we can't be use by closed interface. The second is a problem that can be happen when we gather data about process. When we measure the development process for enhancement of it, we can get data with tools, but current tools are not prepared to measurement of development process. In this study, we explained that process information tool is needed and proposed analysis and design methodology and evaluation standard. Finally, we considered and evaluated for problems which can be happened when construct environment which is based on this result of study.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.11_12
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• pp.717-721
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• 2005

With HTTP/1.0, a single request means a single HTTP connection so that the granular unit of dispatching is the same as real load. But with persistent HTTP connection, multiple requests may arrive on a single TCP connection. Therefore, a scheme that dispatches load at the granularity of individual requests constrains the feasible dispatching policies In this paper we propose a new connection dispatching polity for supporting HTTP/1.1 persistent connections in cluster-based Web servers. When the request of a base html file arrives, the dispatcher gets the subsequent load arriving on that connection using the embedded objects information. After the dispatcher stores the load information in Load Table, the dispatcher employs the connection aging strategy on live persistent connections on the passage of time. The results of simulation show about $1.7\%\~16.8\%$ improved average response time compared to existing WLC algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.3
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• pp.261-266
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• 2019

Flow cytometry is an electrical detection system that provides precise and diverse optical properties to cells and micro particles. Flow cytometry, which provides multidimensional information including cell size and granularity through light scattering and fluorescence emission generated by the induction of light of a specific wavelength to the fluorescently treated cells or micro particles, plays an important role in biomedical and biophysical fields. However, it has some drawbacks such as high cost, size of the instrument and limitation in selecting fluorescent dyes. Therefore, in this paper, a low cost compact fluorescent detection system is developed using light-emitting diode and microcontroller. The proposed fluorescence detection system has a replaceable the light source/fluorescence filter/photodetector and constructed by 3D printer, so that the user can design a customized system according to the selected fluorescent dyes. The fluorescence intensity was measured by varying the number of fluorescently labeled cells, and the measured intensities showed a high linearity within the tested concentration ranges.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1553-1571
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• 2018

Currently, many of schemes for smart grid data aggregation are based on a one-level gateway (GW) topology. Since the data aggregation granularity in this topology is too single, the control center (CC) is unable to obtain more fine-grained data aggregation results for better monitoring smart grid. To improve this issue, Shen et al. propose an efficient privacy-preserving cube-data aggregation scheme in which the system model consists of two-level GW. However, a risk exists in their scheme that attacker could forge the signature by using leaked signing keys. In this paper, we propose a secure and fine-grained electricity consumption aggregation scheme for smart grid, which employs the homomorphic encryption to implement privacy-preserving aggregation of users' electricity consumption in the two-level GW smart grid. In our scheme, CC can achieve a flexible electricity regulation by obtaining data aggregation results of various granularities. In addition, our scheme uses the forward-secure signature with backward-secure detection (FSBD) technique to ensure the forward-backward secrecy of the signing keys. Security analysis and experimental results demonstrate that the proposed scheme can achieve forward-backward security of user's electricity consumption signature. Compared with related schemes, our scheme is more secure and efficient.

• Journal of Korea Multimedia Society
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• v.8 no.2
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• pp.211-224
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• 2005

With the wide acceptance of the Internet and the Web, volumes of information and related users have increased and companies have become to need security mechanisms to effectively protect important information for business activities and security problems have become increasingly difficult. This paper proposes a improved access control model for access control enforcement in enterprise environments through the integration of the temporal constraint character of the GT-RBAC model and sub-role hierarchies concept. The proposed model, called Extended GT-RBAC(Extended Generalized Temporal Role Based Access Control) Model, supports characteristics of GTRBAC model such as of temporal constraint, various time-constrained cardinality, control now dependency and separation of duty constraints(SoDs). Also it supports unconditional inheritance based on the degree of inheritance and business characteristics by using sub-roles hierarchies in order to allow expressing access control policies at a finer granularity in corporate enterprise environments.

• Journal of KIISE:Information Networking
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• v.32 no.6
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• pp.676-686
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• 2005

The Internet users as well as network providers are eager to have different qualities of service among users beyond the best-effort. In this paper, we propose a scheduling algorithm that provides a differentiated service in the granularity of user sessions. The proposed algorithm is a Hierarchical Deficit Round-Robin (H-DRR) algorithm that is an extension of an existing DRR algorithm. A main advantage is that H-DRR provides service differentiation for throughput-intensive applications such as FTP as well as delay-sensitive applications such as telnet or VoIP without distinguishing the types of applications. The most importance in providing a service differentiation in term of network providers is to have controllability and predictability. We show that H-DRR is superior to DRR in terms of controllability and predictability through both mathematical analysis and simulation experiments. Nevertheless, H-DRR requires O(1) complexity for implementation.