• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.1159-1160
• /
• 2006

As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, this has raised potential problems of network protection on electrical power system. One of the numerous problems is an Island phenomenon. There has been an argument that because the probability of islanding is extremely low it may be a non-issue in practice. However, there are three counter-arguments: First, the low probability of islanding is based on the assumption of 100% power matching between the PVPCS and the islanded local loads. In fact, an island can be easily formed even without 100% power matching (the power mismatch could be up to 30% if only traditional protections are used, e.g. under/over voltage/frequency). The 30% power-mismatch condition will drastically increase the islanding probability. Second, even with a larger power mismatch, the time for voltage or frequency to deviate sufficient to cause a trip, plus the time required to execute the trip (particularly if conventional switchgear is required to operate), can easily be greater than the typical re-close time on the distribution circuit. And, third, the low-probability argument is based on the study of PVPCS. Especially, if the output power of PVPCS equals to power consumption of local loads, it is very difficult for the PVPCS to sustain the voltage and frequency in an island. Unintentional islanding of PVPCS may result in power-quality issues, interference to grid-protection devices, equipment damage, and even personnel safety hazards. So the verification of anti-islanding performance is strongly needed. In this paper, the authors propose the improved RPV method through considering power quality and anti-islanding capacity of grid-connected three-phase PVPCS in IEEE Std 1547 ("Standard for Interconnecting Distributed Resources to Electric Power Systems"). And the simulation and experimental results are verified.

• Journal of Korea Multimedia Society
• /
• v.17 no.12
• /
• pp.1402-1411
• /
• 2014

Buyer-seller watermarking protocol is defined as the practice of imperceptible altering a digital content to embed a message using watermarking in the encryption domain. This protocol is acknowledged as one kind of copyright protection techniques in electronic commerce. Buyer-seller watermarking protocol is fundamentally based on public-key cryptosystem that is operating using the algebraic property of an integer. However, in general usage, digital contents which are handled in watermarking scheme mostly exist as real numbers in frequency domain through DCT, DFT, DWT, etc. Therefore, in order to use the watermarking scheme in a cryptographic protocol, digital contents that exist as real number must be transformed into integer type through preprocessing beforehand. In this paper, we presented a new watermarking scheme in an encrypted domain in an image that is based on the block-DCT framework and homomorphic encryption method for buyer-seller watermarking protocol. We applied integral-processing in order to modify the decimal layer. And we designed a direction-adaptive watermarking scheme by analyzing distribution property of the frequency coefficients in a block using JND threshold. From the experimental results, the proposed scheme was confirmed to have a good robustness and invisibility.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.41 no.2
• /
• pp.35-45
• /
• 2023

First, The spatial distribution characteristics of old big trees were analyzed using ArcGIS figures by combining basic information such as species and ages of old big trees in Handan City, which were compiled by the local bureau of landscaping. The types of species, distribution by ages of trees, ownership status, growth status, and diversity status were comprehensively analyzed. Statistically, Styphnolobium, Acacia, Gleditsia, and Albizia of Fabaceae accounted for the majority, of which Sophora japonica accounted for the highest proportion. Sophora japonica is widely and intensively distributed to each prefecture and district in Handan city. According to the age and distribution, the old big trees over 1000 years old were mainly Sophora japonica, Zelkova serrata, Juniperus chinensis, Morus australis Koidz., Dalbergia hupeana Hance, Ceratonia siliqua L., and Pistacia chinensis, and Platycladus orientalis. Second, as found in each type of old big tree status, various types of old big tree status were investigated, the protection management system, protection management process, and protection management benefits were studied, and the protection of old big tree was closely related to the growth environment. Currently, the main driving force behind the protection of old big trees is the worship of old big trees. By depositing its sacredness to the old big tree and sublimating the natural character that nature gave to the old big tree into a guiding consciousness of social activities, nature's "beauty" and personality's "goodness" are well combined. The protection state of the old big tree is closely related to the degree of interaction with the surrounding environment and the participation of various cultures and subjects. In the process of continuously interacting with the surrounding environment during the long-term growth of old big trees, it seems that a natural sanctuary was formed around old big trees in the process of voluntarily establishing a "natural-cultural-scape" system involving bottom-up and top-down cross-regions, multicultural and multi-subjects. Third, China focused on protecting and recovering old big trees, but the protection management system is poor due to a lack of comprehensive consideration of historical and cultural values, plant diversity significance, and social values of old big trees in the management process. Three indicators of space's regional characteristics, property and protection characteristics, and value characteristics can be found in the evaluation of the natural characteristics of old giant trees, which are highly valuable in terms of traditional consciousness management, resource protection practice, faith system construction, and realization of life community values. A systematic management system should be supported as to whether they can be protected and developed for a long time. Fourth, as the perception of protected areas is not yet mature in China, "natural sanctuary" should be treated as an important research content in the process of establishing a nature reserve system. The form of natural sanctuary management, which focuses on bottom-up community participation, is a strong supplement to the current type of top-down nature reserve management in China. Based on this, the protection of old giant trees should be included in the form of a nature reserve called a natural monument in the nature reserve system. In addition, residents of the area around the nature reserve should be one of the main agents of biodiversity conservation.

• Korean Journal of Soil Science and Fertilizer
• /
• v.43 no.5
• /
• pp.684-695
• /
• 2010

Geographic information system (GIS) is being increasingly used for decision making, planning and agricultural environment management because of its analytical capacity. GIS and remote sensing have been combined with environmental models for many agricultural applications on monitoring of soils, agricultural water quality, microbial activity, vegetation and aquatic insect distribution. This paper introduce principles, vegetation indices, spatial data structure, spatial analysis of GIS and remote sensing in agricultural applications including terrain analysis, soil erosion, and runoff potential. National Academy of Agricultural Science (NAAS), Rural Development Administration (RDA) has a spatial database of agricultural soils, surface and underground water, weeds, aquatic insect, and climate data, and established a web-GIS system providing spatial and temporal variability of agricultural environment information since 2007. GIS-based interactive mapping system would encourage researchers and students to widely utilize spatial information on their studies with regard to agricultural and environmental problem solving combined with other national GIS database. GIS and remote sensing will play an important role to support and make decisions from a national level of conservation and protection to a farm level of management practice in the near future.

• Journal of environmental and Sanitary engineering
• /
• v.19 no.4 s.54
• /
• pp.34-47
• /
• 2004

Although Environmental Impact Assessment(EIA) in Korea has been improved markedly over the past two decades, by enlarging the range of projects for assessment, instituting pub lic participation and environmental monitoring, and similar measures, it remains deficient in its coverage of human health in Environmental Impact Statements(EISs). Health Impact Assessment(HIA) can supply the necessary correctives. HIA is a combination of procedures, methods and tools by which a policy, programme, projects or legislative procedure may be judged for its potential effects on the health of a population, and the distribution of these effects within it. The principle of health protection is, however, established as a primary concern in EIA processes, in practice health is scarcely mentioned or the discussion is limited to a description of effects through the biophysical environment. The whole range of possible effects on health, including those mediated by socio-economic factors is often ignored, and no effective mechanism are in place to successfully incorporating health criteria and expertise into environmental, assessment(EA) that include ElA, SEA. These are foremost among the current issues facing EIA in Korea.

• Journal of Korea Water Resources Association
• /
• v.31 no.6
• /
• pp.685-694
• /
• 1998

Protection of groundwater resources from contamination has been of increasing concern throughout the past decades. In practice, however, groundwater monitoring is performed based on the experience and intuition of experts or on the convenience. In dealing with groundwater contamination, we need to know what contaminants have the potential to threat the water quality and the distribution and concentration of the plumes. Monitoring of the subsurface environment through remote geophysical techniques or direct sampling from wells can provide such information. Once known, the plume can be properly managed. Evaluation of existing methodologies for groundwater monitoring network design revealed that one should select an appropriate design method based on the purpose of the network and the availability of field information. Integer programming approach, one of the general purpose network design tools, and a cost to-go function evaluation approach for special purpose network design were tested for field applicability. For the sam contaminated aquifer, two approaches resulted in different well locations. The amount of information, however, was about the same.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.16-16
• /
• 2011

Statistics of extreme rainfall play a vital role in engineering practice from the perspective of mitigation and protection of infrastructure and human life from flooding. While flood frequency assessments, based on river flood flow data are preferred, the analysis of rainfall data is often more convenient due to the finer spatial nature of rainfall recording networks, often with longer records, and potentially more easily transferable from site to site. The rainfall frequency analysis as a design tool has developed over the years in New Zealand from Seelye's daily rainfall frequency maps in 1947 to Thompson's web based tool in 2010. This paper will present a history of the development of New Zealand rainfall frequency analysis methods, and the details of the latest method, so that comparisons may in future be made with the development of Korean methods. One of the main findings in the development of methods was new knowledge on the distribution of New Zealand rainfall extremes. The High Intensity Rainfall Design System (HIRDS.V3) method (Thompson, 2011) is based upon a regional rainfall frequency analysis with the following assumptions: $\bullet$ An "index flood" rainfall regional frequency method, using the median annual maximum rainfall as the indexing variable. $\bullet$ A regional dimensionless growth curve based on the Generalised Extreme Value (GEV), and using goodness of fit test for the GEV, Gumbel (EV1), and Generalised Logistic (GLO) distributions. $\bullet$ Mapping of median annual maximum rainfall and parameters of the regional growth curves, using thin-plate smoothing splines, a $2km\times2km$ grid, L moments statistics, 10 durations from 10 minutes to 72 hours, and a maximum Average Recurrence Interval of 100 years.

• Journal of the Korean Solar Energy Society
• /
• v.28 no.2
• /
• pp.64-69
• /
• 2008

As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, these have raised potential problems of network protection on electrical power system. One of the numerous problems is an Islanding phenomenon. There has been an argument that it may be a non-issue in practice because the probability of islanding is extremely low. However, there are three counter-arguments: First, the low probability of islanding is based on the assumption of 100% power matching between the PVPCS and the islanded local loads. In fact, an islanding can be easily formed even without 100% power matching (the power mismatch could be up to 30% if only traditional protections are used, e.g. under/over voltage/frequency). The 30% power-mismatch condition will drastically increase the islanding probability. Second, even with a larger power mismatch, the time for voltage or frequency to deviate sufficiently to cause a trip, plus the time required to execute a trip (particularly if conventional switchgear is required to operate), can easily be greater than the typical re-close time on the distribution circuit. Third, the low-probability argument is based on the study of PVPCS. Especially, if the output power of PVPCS equals to power consumption of local loads, it is very difficult for the PVPCS to sustain the voltage and frequency in an islanding. Unintentional islanding of PVPCS may result in power-quality issues, interference to grid-protection devices, equipment damage, and even personnel safety hazards. Therefore the verification of anti-islanding performance is strongly needed. In this paper, improved RPV method is proposed through considering power quality and anti-islanding capacity of grid-connected single-phase PVPCS in IEEE Std 1547 ("Standard for Interconnecting Distributed Resources to Electric Power Systems"). And the simulation results are verified.

• The Korean Journal of Pesticide Science
• /
• v.4 no.2
• /
• pp.1-10
• /
• 2000

Fungicide resistance study in Korea is still in its infancy, and most of those resistance studies are largely limited to newness of the detected resistant strains. In future, detection of fungicide-resistant strains has to be based on sensitivity distribution of pathogen populations to certain fungicides, and standard levels of certain fungicides for resistance should be determined under the basis of this data. Most of the early research on fungicide resistance in Korea has overlooked this point, and resulted in inconsistency and confusion for monitoring sensitivity shift of pathogen population among individual researchers. Fungicide resistance detected in vitro tests has to be documented in field trials by examining control efficacy against resistant and wild-type pathogen populations. Resistance detection in wife has to be correlated with lower activity in practice. Using this process, fungicide resistance will have a practical meaning. Fitness evaluation of resistant strains for survival is, in particular, of importance to determine the future stability of the resistance in the pathogen population. In fields, sensitivity change of pathogen populations should be carefully monitored with and without fungicide selection pressures to establish long-term management strategies against fungicide resistance. It is becoming an urgent task to provide information through research for designing and implementing successful counter-measures against fungicide resistance problems in Korea.

• Current Research on Agriculture and Life Sciences
• /
• v.31 no.4
• /
• pp.286-294
• /
• 2013

Increasing concern for the health, well-being, and income of the people has expectedly brought continuous increase in the industrial value of medicinal plants in recent years as these are also used in foods and cosmetics. However, Korea's increased import of these products from China due to the FTA contract causes negative effects on its industrial value. In this regard, various measures for medicinal crop seed development and production, organization and expansion of circulation and forest land use deregulation are needed to promote the agricultural food industry including medicinal plants. As a measure, first, a database of medicinal plants should be built that can help to promote the national medicinal industry and the seed management system. Second, agricultural productivity should be enhanced via the development and supply of varieties of high quality medicinal plants. Third, there should be a good practice of the system maintenance for the production and supply of medicinal crop seeds. Fourth, production and distribution system of medicinal plants should be established by standardization of high quality seeds. Nowadays, the consumption pattern of medicinal crops is changing from direct ingestion to cosmetics, drugs, and food and this is expected to increase continuously. Consequently, the increased production of medicinal crops will support the development policy and the institutional improvement in response to this trend of the positive change of industrialization.