• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2B
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• pp.76-81
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• 2008

LEACH (Low Energy Adaptive Clustering Hierarchy) has been proposed as a routing protocol with a hierarchical structure, in order to achieve the energy efficiency that is of primary importance in the wireless sensor networks. A wireless sensor network adopting LEACH is composed of a few clusters, each of which consists of member nodes that sense the data, and head nodes that deliver the collected data from member nodes to a sink node that is connected to a backbone network. A head node in a cluster allocates TDMA slots to its member nodes without taking into account whether they have data to transmit or not, thus resulting in inefficiency of energy usage of head node that remains in active mode during the entire round time. This motivates us to propose a scheme to improve the energy efficiency of LEACH, by assigning TDMA slots only to those member nodes who have data to send. As a result, the head node can remain sleep during the period of no data transmission from member nodes, leading to the substantial energy saving. By using the ns-2 simulator, we evaluate the performance of the proposed scheme in comparison with the original LEACH. Experimental results validate our scheme, showing a better performance than original LEACH in terms of the number of outliving nodes and the quantity of energy consumption as time evolves.

• Journal of Climate Change Research
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• v.1 no.1
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• pp.51-57
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• 2010

Recently the number of motorcycles has increased in urban area, and it is believed that motorcycle is one of the air pollution and greenhouse gas emission sources. But the greenhouse gas emission from motorcycle has been high uncertainty due investigation of a lack of activity data and emission factors in Korea. So in this study, the greenhouse gas emission from motorcycle is estimated by considering the population of moped and VKT(vehicle kilometers travelled) of motorcycle by recent other studies. And the emissions by IPCC Tier 2 and Tier 3 methodology are calculated and compared. As the results, the nationwide $CO_2$ equivalent emissions from motorcycles by Tier 2 and Tier 3 method are calculated as 2,758 kton/yr and 2,739 kton/yr in 2008. The contribution ratio of this emission is estimated as 2.7% in on-road transport sector.

• Journal of Life Science
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• v.13 no.1
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• pp.21-28
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• 2003

The purpose of this experiment was to compare the energy expenditure and the physiological response among two groups by percent body fat(group A: 30-35% body fat, B: 35-40% body fat) to walking and running at several equivalent speeds. Subjects in group A and B followed A group(mean$\pm$SD, age; 24.0$\pm$0.4yrs, body fat; 32.3$\pm$0.7) and B group (age; 25.2$\pm$0.7yrs, body fat; 36.7$\pm$0.9). The walking and running protocol consisted of treadmill speeds for five min at each of the following speeds: 5.0, 5.5, 6.0, 6.5, 7.0 km.$hr^{-1}$. The obtained data reveal in group A, the rate of oxygen consumption and energy expenditure was higher during walking compared to running ate treadmill speeds $\geq$ 6.6km.$hr^{-1}$. In group 5, the rate of oxygen consumption and energy expenditure was higher during walking compared to running ate treadmill speeds $\geq$ 6.8km.$hr^{-1}$. Heart rates and respiratory exchange ratio were higher at treadmill speeds $\geq$5.8 in group A and $\geq$5.5 in group B. these findings demonstrated that a difference of percent body fat in obese women have no large effect on energy efficiency of walking, but walking within speeds 6.5~7.0km/hr resulted in rates of energy expenditure that were as high or higher than jogging at the same speeds even though the relative stress was greater during walking.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.32-32
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• 2011

Cold Pad batch(CPB)처리에 의한 직물 전처리 공정은 특히 저온처리방식이라 에너지 소모가 적으며, 발생되는 대기오염 및 용수사용량이 연속식 방법에 비해 약 30%이상 절감되는 경제적 친환경적인 기술로 특히 정련과 표백을 동시에 수행할 수 있다. CPB 전처리는 호발, 정련, 표백을 포함하는 공정으로 일욕으로 처리시 패딩, 수세, 와인딩 공정을 단축시키기 때문에 약품 소비량 감소와 에너지 사용 절감 효과가 있어 전 세계적으로 확산되고 있는 Green Technology이다. 본 연구에서는 CPB용 다기능성 일욕형 조제에 개발하기 위해 전처리시 정련, 표백성에 대한 연구를 진행하였다. 시료는 NP/C 교직물을 사용하였고, CPB 처리액은 원료 및 첨가용제를 여러 비율로 조합하여 조제를 formulation 하였다. 이를 사용하여 패딩, 배칭, 수세 및 건조하여 전처리를 하였다. 표백된 정도를 파악하기 위해 Macbeth Color Eye-3100을 사용하여 백도(whiteness(CIE))를 5회 평균값을 구하여 측정 하였다. 정련된 정도를 비교하기 위해 C.I.Reactive Red 238의 2g/l 용액을 사용하여 wicking test를 하였다. 1분간 흡수높이를 측정하여 정련성을 확인하였다. 각각의 첨가용제를 비교한 결과 isopropyl alcohol을 첨가 시 hexylene glycol, butyl diglycol를 첨가한 경우에 비해 높은 흡수높이를 나타내었다. isopropyl alcohol의 농도별 정련성을 알아보기 위해 0%, 5%, 10%의 농도로 처리하였다. 그 결과 isopropyl alcohol 첨가량이 많을수록 정련성이 증가하였다. 다기능성 일욕조제의 문제점인 알칼리 안정성 부족을 보완하기 위해 polyoxyethlylene tridecyl ether derivatieves(LAP300)의 인화물을 첨가하였다. LAP300의 첨가량이 증가할수록 정련성이 증가하는 경향을 나타내었다. 알칼리 안정성 및 타 성능(정련성, 백도, 킬레이트 성)을 종합적으로 평가하여 향후, CPB용 다기능성 일욕형 조제의 개발에 대한 연구를 진행할 계획이다.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.320-325
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• 2020

This study aimed to analyze thermo-keeping and economic feasibility by utilizing silica aerogel, which has been attracting attention as a new material, complementing the disadvantages of the conventional multi-layered thermal screen, and producing and installing multi-layered thermal screen. The multi-layered thermal screen used in the experiment was produced in two combinations using a non-woven fabric containing silica aerogel and measured and compared the temperature and fuel consumption changes due to differences in practice with the multi-layered thermal screen being sold and used on the market. Experimental results show that the temperature and relative humidity changes due to the differences of the multi-layered thermal screens in the single-span greenhouse and the multi-span greenhouse were small but remained almost the same temperature and relative humidity. It is judged that this shows that the multi-layered thermal screen using silica aerogel is not inferior to the conventional multi-layered thermal screen. As a result of a comparative analysis of heating energy, the aerogel-based multi-layered thermal screen reduced fuel consumption by about 15% in the single-span greenhouse and about 20% in the multi-span greenhouse compared to the conventional multi-layered thermal screen. It is clear that heating energy is saved as a greenhouse size and duration increase. It was found that the silica aerogel-based multi-layered screen was more breathable and warmer than the conventional multi-layered thermal screen, but It was found that the multi-layered screen used in the multi-span greenhouse was heavier and stiff compared with the conventional multi-layered thermal screen, indicating less workability and operability. Therefore, improvements were applied to the multi-layered screens used in the single-span greenhouses. It was confirmed that the replacement of internal insulation materials reduced thickness and improved stiffness so that there could be sufficient possibility for farmers to use.

• Food Engineering Progress
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• v.21 no.1
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• pp.42-48
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• 2017

The purpose of this study was to verify the drying characteristics of steamed sweet potato and to establish optimal drying conditions for far-infrared drying of steamed sweet potato. 4 kg of steamed sweet potato was sliced to thicknesses of 8 and 10 mm, and dried by a far-infrared dryer until a final moisture content of $25{\pm}0.5%$. The far-infrared dryer conditions were an air velocity of 0.6, 0.8 m/s and drying temperature of 60, 70, and $80^{\circ}C$. The results can be summarized as follows. The drying time tended to be reduced as temperature and air velocity for drying increased. The Lewis and Modified Wang and Singh models were found to be suitable for drying of steamed sweet potato by a far-infrared dryer. The color difference was 35.09 on the following conditions: Thickness of 8 mm, temperature of $80^{\circ}C$, and air velocity of 0.8 m/s. The highest sugar content ($59.11^{\circ}Brix$) was observed on the conditions of a thickness of 8 mm, temperature of 80, and air velocity of 0.8 m/s. Energy consumption decreased on the conditions of higher temperature, slower air velocity, and thinner steamed sweet potato.

• Journal of the Korean Wood Science and Technology
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• v.48 no.2
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• pp.217-230
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• 2020

Global warming has increased interest in reducing greenhouse gas emissions. And a policy has effort to reduce energy consumption as a greenhouse gas reduction plan. In Korea, 25% of total energy is consumed in the building sector. In order to reduce energy consumption of buildings, it is possible to expand the utilization of wood as a structural material or thermal insulation materials with low thermal conductivity. It is also reported that when used as an interior finishing material, the energy consumption of the building is reduced by up to 7% by insulation performance. In this study, the heat transfer characteristics and the heat capacity were compared according to the three type of finishing materials(cement, paulownia coreana, medium density fiberboard) normally used as indoor finish materials. Through this study, most of the heat transfer volumes are transferred in the form of radiant heat, and the result was derived from the highest amount of energy and heat transfer in the use of paulownia coreana. When indoor finishing materials are used as wood, it is deemed that energy efficiency inside the building will be improved.

• Journal of Internet Computing and Services
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• v.15 no.3
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• pp.1-10
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• 2014

The cloud computing paradigm introduced pay-per-use models in which IT services can be created and scaled on-demand. However, service providers are still concerned about the constraints imposed by their physical infrastructures. In order to keep the required QoS and achieve the goal of upholding the SLA, virtualized resources must be efficiently consolidated to maximize system throughput while keeping energy consumption at a minimum. Using ANN, we propose a predictive SLA-aware approach for consolidating virtualized resources in a cloud environment. To maintain the QoS and to establish an optimal trade-off between performance and energy efficiency, the server's utilization threshold dynamically adapts to the physical machine's resource consumption. Furthermore, resource-intensive VMs are prevented from getting underprovisioned by assigning them to hosts that are both capable and reputable. To verify the performance of our proposed approach, we compare it with non-optimized conventional approaches as well as with other previously proposed techniques in a heterogeneous cloud environment setup.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.955-963
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• 2009

In this paper, we propose a medium access control(MAC) protocol for reducing the energy efficiency and for improving the transmission efficiency in underwater acoustic sensor networks. In underwater environment, the transmission delay is longer and bandwidth is smaller than terrestrial environment. Considering these points, we propose a new MAC protocol to enhance throughput and to manage efficiently the energy of nodes. The proposed protocol operates as a channel reservation scheme to decrease data collisions, and uses a mechanism to control the hidden node problem and the exposed node problem occurred in ad hoc networks. The proposed protocol consists of the slotted based transmission frame and reduces data collisions between nodes by putting separately the reservation period in the transmission frame. In addition, it is able to solve the hidden node problem and the exposed node problem by reservation information between nodes. We carry out the simulation to evaluate the proposed protocol in terms of the average energy consumption, the ratio of collision, throughput, and the average transmission delay, and compare the proposed protocol to a traditional MAC protocol in the underwater environment. The simulation results show that the proposed protocol outperforms the traditional protocol under a various of network parameters.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.149-153
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• 1993

Daily energy expenditures (DEE) of 82 co-eds in a University were estimated simultaneously by use of calorie counter and 15-min check list diary for 3 days, including a weekend day. The results are summarized as follows. The mean values of DEE from 15-min check list diary and calorie counter were 1967kcal and 1649kcal, respectively. DEE obtained with 15-min check list diary seems to be consistent with the results made by others concerning DEE of college female in Korea, but DEE by calorie counter was lower than that. However, DEE by calorie counter show high correlations with anthropometric indices of subjects and DEE by 15-min check list diary. Therefore, DEE by 15-min check list diary was taken as standard and regression equation for predicting DEE of subjects were developed: DEE by 15-min check list diary =3.31186 + 1.18837 $\times$ DEE by calorie counter. This technique for measuring DEE permits us to have more accurate estimate of DEE and acceptable to the subjects. When the subjects classified as underweight, normal, overweight according to relative body weight(RBW), DEE and DEE per kg of body weight were significantly different from each other between three groups based on RBW. The frequency of 15-minute periods with a categorical value of 1 was significantly higher in overweight than underweight and normal groups and the frequency of a categorical value 3 was significantly lower in overweight than underweight group. From the results shown above, physical activity level of overweight group was lower than that of normal and underweight groups.