• ALGAE
• /
• v.32 no.4
• /
• pp.325-336
• /
• 2017

Intertidal community recovery and resilience were investigated with quantitative and qualitative perspectives as a function of disturbance timing. The study was conducted in a lower intertidal rock bed of the southern coast of South Korea. Six replicates of artificial disturbance of a $50cm{\times}50cm$ area were made by clearing all visible organisms on the rocky substrate in four seasons. Each of the seasonally cleared plots was monitored until the percent cover data reached the control plot level. There was a significant difference among disturbance timing during the recovery process in terms of speed and community components. After disturbances occurred, Ulva pertusa selectively preoccupied empty spaces quickly (in 2-4 months) and strongly (50-90%) in all plots except for the summer plots where non-Ulva species dominated throughout the recovery period. U. pertusa acted as a very important biological variable that determined the quantitative and qualitative recovery capability of a community. The qualitative recovery of communities was rapid in summer plots where U. pertusa did not recruit and the community recovery rate was the lowest in winter plots where U. pertusa was highly recruited with a long duration of distribution. In this study, U. pertusa was a pioneer species while being a dominant species and acted as a clearly negative element in the process of qualitative recovery after disturbance. However, the negative effect of U. pertusa did not occur in summer plots, indicating that disturbance timing should be considered as a parameter in understanding intertidal community resilience in temperate regions with four distinct seasons.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2006.06a
• /
• pp.187-192
• /
• 2006

The Korean peninsula has been considered as seismically intermediate region, since seismic activities have not been severe for long time and the active tectonic boundary is also located far away. However, the activities of earthquakes have been increased significantly for last decade. Since currently important structures and facilities are increasing rapidly in the Korean Peninsula, the importance of seismic design are increasing exponentially too. This study used observed ground motion of Fukuoka event including 11 afterschocks and then estimated seismic parameters representing seismic source, propagation effect, considering site amplification. The results were comparable to those of other studies in the same region. The results could be used as basic important parameters for seismic design of the important structures and facilities in Korean peninsula.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.5 no.3
• /
• pp.251-260
• /
• 2003

Tunnel blasting has been performed with V-cut to investigate the characteristics. Blasting vibrations were measured at two directions, the proceed direction and side direction. Propagation characteristics were determined by regression analysis; square root scaled distance and cube root scaled distance with maximum charge per delay of the blast. Testing result, The cross point was 62m in the allowable vibration velocity of 3mm/sec and 46m in 5mm/sec. Also, vibration level with measuring point was highest and decayed fastest, adapting to cube root scaled distance, for the proceed direction on ground.

• Journal of Korean Society for Atmospheric Environment
• /
• v.24 no.5
• /
• pp.538-550
• /
• 2008

Radon is an invisible, odorless, and radioactive gas. It is formed by the disintegration of radium, which is a decay product of uranium. Some amounts of radon gas and its products are present ubiquitously in the soil, water, and air. Particularly high radon levels occur in regions of high uranium content. Although radon is permeable into indoor environment not only through geological features (bed rock and permeability) but also through the construction materials and underground water, the radiation from the geological features is generally main exposure factor. So there can be a problem in a certain space such as the underground and/or relatively poor ventilation condition. In this study, a GIS technique was used in order to investigate spatial distribution of radon measured from sub- way stations of 1 thru 8 in Seoul, Korea in 1991, 1998, 2001, and 2006. Spatial analysis was applied to reproduce the radon distribution. We utilized spatial analysis techniques such as inverse distance weighted averaging (IDW) and kriging techniques which are widely used to relate between different spatial points. To validate the results from the analyses, the jackknife technique for an uncertainty test was performed. When the number of measuring sites was less than 100 and also when the number of omitted sites increased, the kriging technique was better than IDW. On the other hand, when the number of sites was over 100, IDW technique was better than kriging technique. Thus the selection of analytical tool was affected sensitives by the analysis based on the number of measuring sites.

• The Journal of Engineering Geology
• /
• v.10 no.2
• /
• pp.189-214
• /
• 2000

Three study areas of Kwanak campus(Seoul National University), Gapyung and Boeun were selected and classified according to bedrock types in order to investigate soil-gas radon concentrations. Several soil-gas samples showed relatively high radon concentrations in the residual soils which derived from granite bedrock. It also showed that water content of soil and the degree of radioactivity disequilibrium was a secondary factor governing radon emanation and distribution of radon radioactivity. The results of radon concentrations and working levels for forty rooms in Kwanak campus, Seoul National University, showed that indoor basement rooms under poor ventilation condition can be classified as high radon risk zone having more than EPA guideline(4 pCi/L). Some results of section analysis which was surveyed in the fault zone of Kyungju and Gapyung area confirmed the existence of fault-associated radon anomalies with a meaning of radon risk zone.

• Journal of Korea Water Resources Association
• /
• v.51 no.4
• /
• pp.313-322
• /
• 2018

The height of the steps was almost the same as the grain size of bed materials and increased with channel slope. The step widths and step wavelengths are almost the same size, and the step wavelength was decreased when the channel slope was increased. It was analyzed that there was a clear correlation between channel width and step width, and the step width increases with channel width. In addition, the step wavelength was scaled by channel width, and the step height is governed by the grain size of the rock forming the step, so that the profile structure of the step-pool was changed according to the channel slope. the scale of the pool was found to be highly correlated with the channel width, grain size, and slope gradient. Therefore, the characteristics of step-pool structure in mountain streams were influenced by various factors, but it can be explained as the grain size, channel width and channel slope.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.15 no.1
• /
• pp.57-63
• /
• 2011

In this study, a ground motion response spectrum for the seismic risk assessment of low and intermediate level radioactive waste repositories was developed. For the development of the ground motion response spectrum, a probabilistic seismic hazard analysis (PSHA) was performed. Through the performance of a PSHA, a seismic hazard curve which was based on a seismic bed rock was developed. A uniform hazard spectrum was determined by using a developed seismic hazard curve. Artificial seismic motions were developed based on the uniform hazard spectrum. A seismic response analysis was performed on the developed artificial seismic motion. Finally, an evaluation response spectrum for the seismic risk assessment analysis of low and intermediate level radioactive waste repositories was developed.

• Journal of The Geomorphological Association of Korea
• /
• v.23 no.3
• /
• pp.79-92
• /
• 2016

Samples from two boreholes of coastal dune field at Jangho-ri coast, Gochang was studied. These were analyzed by grain size analysis geochemical analysis, and the application of OSL dating method to understand the development during the Holocene. The boreholes SB8 and SB9 were classified into three different sedimentary layers by their mean grain size and geochemical characteristics. The results revealed that the upper sand layer is equivalent to the present coastal dune layer, which developed since 1,200 years ago; the silt layer in the middle to the dune slack or lagoon sedimentation layer, which developed between 1,200 and 6,000 years ago; and the sand layer at the bottom to the paleo coastal dune that developed between 6,000 and 7,000 years ago. It was proposed that the forming material of current coastal dune was supplied from the sandy flat in coastal area, while the middle silt layer was supplied from the weathered soil of a bed rock by the comparison with material of surrounding area. In the case of coastal dune, concentrated layer of sands were identified which were buried about 300 and 1,200 years ago, which is identified as the little ice age. This study confirmed the development of Jangho-ri coastal dunes after Holocene Climate Optimum period, and it is likely to assist in the understanding of coastal dunes development.

• Journal of Forest and Environmental Science
• /
• v.27 no.3
• /
• pp.169-181
• /
• 2011

The purpose of this study was to understand the geographical and environmental distribution of animals and plants in Baekdudaegan region using field survey and GIS data. Crucial factors were selected and analyzed to understand the distributional characteristics of wild animals (16 species in 5 orders) and rare endemic plants (20 species in 12 orders). These crucial factors include stand factor (forest type, DBH class, and crown density), soil factor (bed rock, soil texture, and organic matter), geographical factor (elevation, slope, aspect) and climatic factor (temperature, rain fall, humidity). Finally, ten crucial factors were selected by statistical analysis and categorized for analyzing geographical and environmental features. Three orders such as Rodentia, Carnivora, and Artiodactula in wild animal showed the similar habitat characteristics with the small diameter and the elevation range from 801 to 1,000m. The Hydropotes inermis of Artiodactyla and Rattus norvegicus of Rodentia were different in the type of orders, but they had the similar habitat characteristics with the coniferous forest and loam. On the other hand, four orders such as Tubiflorales, Liliales, Ericales, and Rhamnales in the rare and endemic plants were showed high occurrence rate in the organic matter between 4 and 6%. The Rodgersia podophylla of Rosales and Gastrodia elata Blume of Microspermae were different in the type of orders, but they had the similar habitat characteristics with the stand factor and soil factor.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.32 no.4
• /
• pp.24-36
• /
• 2014

The result of the research conducted for the purpose of investigating the semantic value and the layout of the Cheongryu Gugok of Dorimsa Valley, which exhibits a high level of completeness and scenic preservation value among the three gugoks distributed in the area around Mt. Dongak of Gogseong is as follows.4) The area around Cheongryu Gugok shows a case where the gugok culture, which has been enjoyed as a model of the Neo-Confucianism culture and bedrock scenery, such as waterfall, riverside, pond, and flatland, following the beautiful valley, has been actually substituted, and is an outstanding scenery site as stated in a local map of Gokseong-hyeon in 1872 as "Samnam Jeil Amban Gyeryu Cheongryu-dong(三南第一巖盤溪流 淸流洞: Cheongryu-dong, the best rock mooring in the Samnam area)." Cheongryu Gugok, which is differentiated through the seasonal scenery and epigrams established on both land route and waterway, was probably established by the lead of Sun-tae Jeong(丁舜泰, ?~1916) and Byeong-sun Cho(曺秉順, 1876~1921) before 1916 during the Japanese colonization period. However, based on the fact that a number of Janggugiso of ancient sages, such as political activists, Buddhist leaders, and Neo-Confucian scholars, have been established, it is presumed to have been utilized as a hermit site and scenery site visited by masters from long ago. Cheongryu Gugok, which is formed on the rock floor of the bed rock of Dorimsa Valley, is formed in a total length of 1.2km and average gok(曲) length of 149m on a mountain type stream, which appears to be shorter compared to other gugoks in Korea. The rock writings of the three gugoks in Mt. Dongak, such as Cheongryu Gugok, which was the only one verified in the Jeonnam area, total 165 in number, which is determined to be the assembly place for the highest number of rock writings in the nation. In particular, a result of analyzing the rock writings in Cheongryu Gugok totaling 112 places showed 49pieces(43.8%) with the meaning of 'moral training' in epigram, 21pieces (18.8%) of human life, 16pieces(14.2%) of seasonal scenery, and 12pieces(10.6%) of Janggugiso such as Jangguchur, and the ratio occupied by poem verses appeared to be six cases(3.6%). Sweyeonmun(鎖烟門), which was the first gok of land route, and Jesiinganbyeolyucheon(除是人間別有天) which was the ninth gok of the waterway, corresponds to the Hongdanyeonse(虹斷烟鎖) of the first gok and Jesiinganbyeolyucheon of the ninth gok established in Jaecheon, Chungbuk by Se-hwa Park(朴世和, 1834~1910), which is inferred to be the name of Gugok having the same origin. In addition, the Daeeunbyeong(大隱屛) of the sixth gok. of land route corresponds to the Chu Hsi's Wuyi-Gugok of the seventh gok, which is acknowledged as the basis for Gugok Wollim, and the rock writings and stonework of 'Amseojae(巖棲齋)' and 'Pogyeongjae(抱經齋)' between the seventh gok and eighth gok is a trace comparable with Wuyi Jeongsa(武夷精舍) placed below Wuyi Gugok Eunbyeon-bong, which is understood to be the activity base of Cheongryu-dong of the Giho Sarim(畿湖士林). The rock writings in the Mt. Dongak area, including famous sayings by masters such as Sunsaeuhje(鮮史御帝, Emperor Gojong), Bogahyowoo(保家孝友, Emperor Gojong), Manchunmungywol(萬川明月, King Joengjo), Biryeobudong(非禮不動, Chongzhen Emperor of the Ming Dynasty)', Samusa(思無邪, Euijong of the Ming Dynasty), Baksechungpwoong(百世淸風, Chu Hsi), and Chungryususuk-Dongakpungkyung(淸流水石 動樂風景, Heungseon Daewongun) can be said to be a repository of semantic symbolic cultural scenery, instead of only expressing Confucian aesthetics. In addition, Cheongryu Gugok is noticeable with its feature as a cluster of cultural scenery of the three religions of Confucian-Buddhism-Taoism, where the Confucianism value system, Buddhist concept, and Taoist concept co-exists for mind training and cultivation. Cheongryu Gugok has a semantic feature and spatial character as a basis for history and cultural struggle for the Anti-Japan spirit that has been conceived during the process of establishing and utilizing the spirit of the learning, loyalty for the Emperor and expulsion of barbarians, and inspiration of Anti-Japan force, by inheriting the sense of Dotong(道統) of Neo-Confucianism by the Confucian scholar class at the end of the Joseon era that is represented by Ik-hyun Choi(崔益鉉, 1833~1906), Woo Jeon(田愚, 1841~1922), Woo-man Gi(奇宇萬, 1846~1916), Byung-sun Song(宋秉璿, 1836~1905), and Hyeon Hwang(黃玹, 1855~1910).