• Molecules and Cells
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• v.26 no.5
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• pp.427-435
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• 2008

In this review, we discuss the genes and the related signal pathways that regulate aging and longevity by reviewing recent findings of genetic longevity models in rodents in reference to findings with lower organisms. We also paid special attention to the genes and signals mediating the effects of calorie restriction (CR), a powerful intervention that slows the aging process and extends the lifespan in a range of organisms. An evolutionary view emphasizes the roles of nutrient-sensing and neuroendocrine adaptation to food shortage as the mechanisms underlying the effects of CR. Genetic and non-genetic interventions without CR suggest a role for single or combined hormonal signals that partly mediate the effect of CR. Longevity genes fall into two categories, genes relevant to nutrient-sensing systems and those associated with mitochondrial function or redox regulation. In mammals, disrupted or reduced growth hormone (GH)-insulin-like growth factor (IGF)-1 signaling robustly favors longevity. CR also suppresses the GH-IGF-1 axis, indicating the importance of this signal pathway. Surprisingly, there are very few longevity models to evaluate the enhanced anti-oxidative mechanism, while there is substantial evidence supporting the oxidative stress and damage theory of aging. Either increased or reduced mitochondrial function may extend the lifespan. The role of redox regulation and mitochondrial function in CR remains to be elucidated.

• Journal of Applied Biological Chemistry
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• v.50 no.1
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• pp.22-28
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• 2007

Most of the uplands in alpine regions during off-season are left as bare soil and thus vulnerable to severe erosion due to the inherent topographical conditions. Appropriate management strategy to cope with this problem is urgently needed, yet few researches have been reported on the effects of winter cover crop and management on soil erosion. We assessed effects of ryegrass (Lolium multiflorum) as cover crop, green manure or mulching residue on soil erosion and quality through field and segment plot lysimeter experiments in alpine uplands. Ryegrass successfully adopted to winter in alpine region based on biomass, nutrient contents, and vigors of top and root systems. Incorporation of ryegrass into soil maintained soil fertility, nutrient uptake, and yield of cabbage exerting potential use as green manure. Cultivation of ryegrass suppressed occurrence of Chinese cabbage pests. Surface coverage by ryegrass as cover crop and mulching residue significantly reduced soil loss up to 96%, when combined with soil conservation management practices. Results revealed maintaining cover crop over winter was beneficial in reducing soil erosion, and sustaining soil quality and Chinese cabbage productivity. This study suggested winter cover crop, followed by green manure and mulching, and conservation tillage system could be one of the best management practices in alpine sloping uplands cultivating Chinese cabbage.

• Journal of the Korean housing association
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• v.17 no.4
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• pp.145-153
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• 2006

Ubiquitous space can be described as a combined space of physical space and digital space. Ubiquitous space possesses new possibilities by combining the two. The concept of ubiquitous home will bring new changes in residential space design. First of all, it makes possible for more convenient and secure home. It has to be developed along with city and town level changes as ubiquitous environment. Secondly, concept of extended space as an extension of living space becomes possible by linking with outside spaces. Thirdly, as consumer requirements for residential spaces will become more versatile by social changes, ubiquitous home can be a good means to meet these versatile consumer requirements by accommodating concept of multi-functional space and flexible space. It is quite important to predict user requirements in rapidly changing social environment and versatile personal inclinations. Instead of POE methodology which can analyze and evaluate in exiting types of designs, storytelling methodology can be used to predict and direct for future requirements of living. The methodology makes scenarios of space usage for future living and extracts design requirements for the living. The concept of intelligent space has to be introduced. It is different from digital home that only accomodate digital devices in space. In intelligent space, space itself has to be recognized as an identity that interacts human directly. Intelligent space recognize human requirements and control digital devices as a response. Multi-functional space is closely related with intelligent space that can changes for business, entertainments as well as for rests by user requirements instantly. Flexible space that also intends to meet requirements of mobility and versatility can be attained through the integration of digital technology into current physical mobile systems. Interaction design becomes integral part for ubiquitous space design along with physical design. For the residential space design, digital illiteracy has to be considered for interaction design. Instead of the concept of passive existence, space itself has to be recognized as active subsistence that reacts with human. Intuitive and natural interaction for human will be a key design element for space-human interface design.

• Journal of Internet Computing and Services
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• v.6 no.6
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• pp.99-106
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• 2005

The task scheduling in multiprocessor system Is one of the key elements in the effective utilization of multiprocessor systems. The optimal assignment of tasks to multiprocessor is, in almost all practical cases, an NP hard problem. Consequently various modern heuristics based algorithms have been proposed for practical reason. Recently, several approaches using Genetic Algorithm (GA) are proposed. However, these algorithms have only one objective such as minimizing cost and makespan. This paper proposes a new task scheduling algorithm using Genetic Algorithm combined simulated annealing (GA+SA) on multiprocessor environment. In solution algorithms, the Genetic Algorithm (GA) and the simulated annealing (SA) are cooperatively used. In this method. the convergence of GA is improved by introducing the probability of SA as the criterion for acceptance of new trial solution. The objective of proposed scheduling algorithm is to minimize makespan and total number of processors used. The effectiveness of the proposed algorithm is shown through simulation studies. In simulation studies, the results of proposed algorithm show better than that of other algorithms.

• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.988-996
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• 2012

Assuming perfect channel state information (CSI), the conventional interference alignment (IA) algorithm in the uplink cellular system suppresses inter-cell interference (ICI) by aligning ICI to a randomly selected reference vector. However, IA in practice relies on limited feedback between base stations and users, resulting in residual ICI. In this paper, we propose the optimization of the reference vector that minimizes the upper-bound of residual ICI power. Secondly, the iterative IA that designs the direction of transmit and receive filter is proposed to minimize the residual ICI as well as maximize the desired signals. Moreover, we propose the user scheduling method combined with proposed IA schemes which provides the multiuser diversity gain in multi-cell environments. Finally, the performance gain of the proposed IA algorithms compared with the existing IA are analyzed and demonstrated by simulation results.

• Journal of Internet Computing and Services
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• v.14 no.1
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• pp.1-7
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• 2013

This paper proposes a technique for applying space-time block coding (STBC) - Alamouti scheme on Multiple Inputs Multiple Output (MIMO) system based on IEEE 802.15.4 standard. It is applied to IEEE 802.15.4 standard in $2{\times}1$ MISO and $2{\times}2$ MIMO systems. Simulation is performed using Matlab and the results are compared with conventional IEEE 802.15.4 approaches, Single Input Single Output (SISO) system and switching diversity $1{\times}2$ Single Input Multiple Output (SIMO) system. The simulations show that applied Alamouti scheme gave better Bit Error Rate (BER) performance compared to combined IEEE 802.15.4 with switching diversity and SISO system.

• Transactions of the KSME C: Technology and Education
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• v.3 no.4
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• pp.273-283
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• 2015

In this study, we suggested the methodology and the results of planning of promising technologies in mechanical engineering by focusing on the case of the Korea Institute of Machinery and Materials (KIMM). For dedicated commitment to planning of promising technologies, KIMM newly introduced task-force called as 'specialist unit'. In addition, KIMM combined the investigation of external environments with the analysis of internal capabilities of KIMM and utilized the bibliographic coupling analysis in the process of the exploring sub themes. Finally, we provided 8 promising fields and their sub themes in the mechanical engineering. Our study contributed to the strategic development of the main research programs of KIMM. Our findings can be also utilized as the best practice of planning of promising technologies in the field of mechanical engineering.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.1
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• pp.87-95
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• 2016

In this study, we develop a model of an open center and load-sensing system and for a main control valve to analyze system characteristics and efficiency using SimulationX. In order to analyze the operating characteristics of the pressure and flow of the main control valve of an open center system, a test was performed at each port. The reliability of the model was confirmed by comparing the similarity of the analysis results with the test results before analyzing the operating characteristics of the system. Development of the load sensing main control valve was performed by adding a flow sharing valve and a notched shape to the open center system based on it's the proven reliability. The authors performed the simulation under the same load conditions in order to compare the efficiency of the systems. Additionally, the combined operation performance was investigated by means of analyzing the characteristics of flow distribution under different load conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.483-491
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• 2014

In this study, a thermodynamic analysis was carried out for a combined power generation system using a low-temperature heat source in the form of sensitive energy and liquefied natural gas cold energy. An ammonia-water mixture, which is a zeotropic mixture, was used as the working fluid, and systems with and without a regenerator were comparatively analyzed. The effects of the mass fraction of ammonia and the condensation temperature of the working fluid on the system variables, including the net work production, exergy destruction, and thermal and exergy efficiencies, are analyzed and discussed. The results show that the performance characteristics of the system varied sensitively with the ammonia concentration or condensation temperature of the working fluid. The system without regeneration was found to be better in relation to the net work per unit mass of the source fluid, whereas the system with regeneration was better in relation to the thermal or exergy efficiency.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.362-365
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• 2015

Silica encapsulated ZnSe quantum dots (QDs) were prepared by employing two microemulsion systems: AOT/water/cyclohexane microemulsions containing ZnSe quantum dots with NP5/water/cyclohexane microemulsions containing tetraethylorthosilicate (TEOS). Using this method, cubic zinc blende nanoparticles (3 nm in diameter) were synthesized and encapsulated by silica nanoparticles (20 nm in diameter). The temperature dependence of photoluminescence (PL) for silica-encapsulated ZnSe QDs was investigated to evaluate this material as a temperature sensor media. The fluorescence emission intensity of silica-encapsulated ZnSe nanoparticles (NPs) was decreased with an increase of ambient temperature over the range from $30^{\circ}C$ to $60^{\circ}C$ and a linear relationship between the temperature and the emission intensity was observed. In addition, the temperature dependence of PL intensity for silica-encapsulated ZnSe NPs showed a reversible pattern on ambient temperature. A reversible temperature dependence of the luminescence combined with its insensitivity toward quenching by oxygen due to silica coating established this material as an attractive media for temperature sensor applications.