• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.50 no.12
• /
• pp.575-583
• /
• 2001

Dynamic Voltage Restorer(DVR) which is installed between the supply and a critical load can restore voltage disturbances in distribution system. The restoration is based on injecting the same voltages as voltage sags. The ideal restoration is compensation to make the load voltages be unchanged. But voltage restoration involves real power or energy injection and the capability of energy storage is limited. So it must be considered how injection energy can be minimized and voltages can be made close to the voltages before fault. This paper describes conventional restoration techniques, which draw minimum energy from the DVR in order to correct a given voltage sag or swell. And this paper proposes a new concept of restoration technique to inject minimum energy. The proposed method is based on the definition of voltage tolerance in load side. Hence using the proposed method a particular disturbance can be corrected with less amount of storage energy compared to those of conventional methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.10a
• /
• pp.367-370
• /
• 2007

Both impluse noise and AWGN (additive white Gaussian noise) are easily corrupted into images, during signal transmission and acquisition. Thus, an algorithm for removing both noises is represented in this paper. An impulse noise detection step can effectively separate impulse noise with AWGN, then in the noise filtering step, by using several parameters, not only impulse noise but also AWGN can be reduced. The value of those parameters are automatically changeable when the standard deviation of AWGN, the impulse noise density, and the spatial distances between pixels are different. Results of computer simulations show that the proposed approach performs better than other conventional filters.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.1216-1222
• /
• 2009

Ecological Engineering (EE) refers to all sustainable engineering that can reduce damage to ecosystems and that adopts ecology as a base and safety as an orientation in order to implement conservation of biodiversity and sustainable development. In short, EE attempts to safeguard the ecological environment while any essential construction projects proceed. EE encompasses many fields, including construction skills, ecosystem preservation, landscape, and even related cultures and so on. Such variety results in greater complexity of construction, and, consequently, indirectly increases the difficulty of construction quality control. The objective of our research is to explore a promising model for EE via an extensive literature survey. This model includes three principal stages: plan-design, construction, and maintenance, along with individual accompanying phases concerned with quality control and vital management. In this article, a river restoration example is adopted to describe in detail the critical points of quality control in the three stages (plan-design, construction, and maintenance) of the construction life cycle. This study proposes an integrated structure for quality management of EE to guarantee its quality and to enhance its core applications in order to achieve long-lasting preservation of the environment.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.5
• /
• pp.1100-1107
• /
• 2016

• Journal of Conservation Science
• /
• v.35 no.3
• /
• pp.217-225
• /
• 2019

The chimi(ridge-end tile) of Wangheungsa temple is the oldest in our country. The upper part of the chimi was excavated from the southern side of Wangheungsa temple and the lower part from the northern side. These parts are considered to be portions of the same chimi, because they are similar in shape and are excavated from two sides of the same temple structure. However, the original shape of the chimi cannot be determined owing to substantial deterioration. Hence, in this study, replicas of the deteriorated chimi portions of Wangheungsa temple were fabricated by employing 3D scanning technology and the computer numerical control machining method. While observing the bending phenomenon of the chimi, the proposed model was warped realistically on the basis of the bending direction of the actual chimi. Consequently, the restoration process was modified several times. The results indicated that no gaps can be found between the upper and lower parts, and the corresponding patterns connect naturally. Furthermore, the proposed method is contactless, safe, operable, reproducible, and appropriate for restoration of artifacts. Additionally, the modeling data is semi-permanent. Hence, if modelling data is appropriately applied as per the characteristics of artifacts, it can be utilized in various fields such as virtual exhibitions, hands-on exhibitions, cultural heritage restoration, and production of teaching aids and souvenirs.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.12 no.5
• /
• pp.59-76
• /
• 2009

This study was conducted to supply basic data for restoration and management of forests in Civilian Control Zone, with surveying naturalized plants around abandoned military camps. The total study sites are 72 abandoned military camps, from Gosung in east region to Paju in west region of Civilian Control Zone. The naturalized index of total area is 12.6%, and naturalized index of east and middle regions are 12.1% and 8.4%. But its index of west region is 15.9%. These results are due to geographical characteristics. The east and middle regions are in steep mountainous districts, and so but west region is flat district, and so naturalized plants was imported by only army. But west region is in flat districts, and so imported method of naturalized plants is very various. The main naturalized plants are Ambrosia trifida and Ambrosia artemisiifolia var. elatior in Civilian Control Zone. The main dispersion pattern of naturalized plants are gravity dispersion pattern ($D_4$) and wind and water dispersion pattern ($D_1$). The all naturalized plants are photophilic plants in survey sites. And so, if abandoned military camps are recovered to forests, the naturalized plants are disappeared because of the change of sunlight condition. So it is necessary to manage and recover forests, even if that area is Civilian Control Zone.

• Ecology and Resilient Infrastructure
• /
• v.2 no.1
• /
• pp.99-104
• /
• 2015

Topsoil including numerous soil seedbanks has been known to be a valuable material for ecological restoration. There is a lack of specific study for its utilization in the field of stream restoration. This study conducted a revaluation of the value of topsoil as a material for stream restoration. Furthermore, an ecological technique using topsoil was applied in an improvement project of a stream environment at the Hwanggujicheon Stream in Korea. Stockpiling and spreading topsoil was specifically applied to the revegetation of a low slope revetment and a high flow plain. The result of this application showed that topsoil played an integral role in eco-friendly restoration in terms of ecological, flood control, economic, and constructional aspects. In conclusion, this study's findings suggest that topsoil is a suitable candidate material for stream restoration.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.13 no.2
• /
• pp.105-113
• /
• 2010

To investigate the restoration procedure on soil physical properties at the surface of visiting road affected by rest-year system. This study was carried out at visiting roads of stream of Chilsun in Jirisan. Mean soil strength in 20cm of soil depth was lower in the Rest-Year System areas (1.5-1.9 times in Site 2, 1.1-7.5 times in Site 3) than in the control (Site 1). Soil strength was recovered by the Rest-Year System in the national park. Mesopore rate (pF 2.7) in 0-15 cm of soil depth was higher in the Rest-Year System areas (1.2 times) than in the control. This indicates that mesopore rate is rapidly restoring in the Rest-Year System areas. Pore space rate in 0-7.5 cm of soil depth was higher in the Rest-Year System areas (23.2% in Site 2, 23.6% in Site 3) than in the control (22.4% in Site 1). Pore space rate in 7.5-15 cm of soil depth was also higher in the Rest-Year System areas (22.9% in Site 2 and Site 3) than in the control (18.9% in Site 1). Soil pore space was remediable by the Rest-Year System. Bulk density in 0-7.5 cm of soil depth was lower in the Rest-Year System areas (1.674g/$cm^3$ in Site 2, 1.668g/$cm^3$ in Site 3) than in the control (1.723g/$cm^3$ in Site 1). Bulk density in 7.5-15 cm of soil depth was lower in the Rest-Year System areas (1.785g/$cm^3$ in Site 2 and 1.721g/$cm^3$ in Site 3) than in the control (1.721g/$cm^3$ in Site 1). Soil bulk density was decreased in the Rest-Year System areas of the national park. Amount of soil erosion was lower in the Rest-Year System areas ($0.017m^3$/km/yr in site 2, $0.023m^3$/km/yr in site 3) than in the control ($0.054m^3$/km/yr in site 1).

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1387-1390
• /
• 1997

In this paper we propose a novel way to restore degraded image using wavelet transform & filterbank. First, we devide a degraded image into 4-suband images using UDWT(Undecimated Wavelet Transform), and then use a proper CLS (Constrained Least Square) filter in each subband. Using a proper CLS filter ineach subband, we can save high grequency components of original image. We reconstruct a restored image from the downsampled subband images using wavelet tansform. Even though there is a trade-off between ISNR and calculation loads, we reduce the calculation loads by using wavelet transform in reconstruction with a negligible degradatiion in ISNR.

• Proceedings of the KIEE Conference
• /
• 1992.07a
• /
• pp.169-171
• /
• 1992

In an automated power distribution systems, the fault situation is controlled from the control center through remotely-controlled sectionalizing switches. In this paper, the service restoration strategy which can yield the minimal switching actions and constraint checking is proposed and an expert system which generates the appropriate switching actions is described.