• Geophysics and Geophysical Exploration
• /
• v.1 no.1
• /
• pp.31-42
• /
• 1998

Recently crosshole seismic tomography has come to be widely used especially for the civil engineering, because it can provide more detail information than any other surface method, although the resolution of tomogram will be inevitably deteriorated to some extent due to the limited wavefield aperture on the nonuniqueness of traveltime inversion. In addition, our field sites often consist of a high-velocity bed rock overlain by low-velocity rock, sometimes with a contrast of more than 45 percent, and furthermore the bed rock is folded. The first arriving waves can be then the refracted ones that travel along the bed rock surface for some source/receiver distances. Thus, the desirable first arrivals can be easily misread that cause severe distortion of the resulting tomogram, if it is concerned with (straight ray) traveltime inversion procedure. In this case, comparision with synthetic data (forward modeling) is a valuable tool in the interpretation process. Besides, abundant information is contained in the crosshole data. For instance, examination of tube waves can be devoted to detecting discontinuities within the borehole such as breakouts, faults, fractures or shear zones as well as the end of the borehole. Specific frequency characteristics of marine silty mud will help discriminate from other soft rocks. The aim of this paper is to present several strategies to analyze and interpret the crosshole data in order to improve the ability at first to determine the spatial dimensions of interwell anomalies and furthermore to understand the underground structures. To this end, our field data are demonstrated. Possibility of misreading the first arrivals was illustrated. Tube waves were investigated in conjunction with the televiewer images. Use of shot- and receiver gathers was examined to benefit the detectabilities of discontinuities within the borehole.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.9
• /
• pp.67-76
• /
• 2010

This paper proposes a image-based water level measurement method, which adapt to the ruler's surface condition. When the surface of a ruler is deteriorated by mud, drifts, or strong light reflection, the proposed method judges the pollution of ruler by comparing distance between two levels: the first one is the end position of horizontal edge region which keeps the pattern of ruler's marking, and the second one is the position where the sharpest drop occurs in the histogram which is construct using image density based on the axis of image height. If the ruler is polluted, the water level is a position of local valley of the section having a maximum difference between the local peak and valley around the second level. If the ruler is not polluted, the water level is detected as the position having horizontal edges more than 30% of histogram's maximum value around the first level. The detected water level is converted to the actual water level by using the mapping table which is construct based on the making of ruler in the image. The proposed method is compared to the ultrasonic based method to evaluate its accuracy and efficiency on the real situation.

• Geophysics and Geophysical Exploration
• /
• v.8 no.3
• /
• pp.201-206
• /
• 2005

Interpretation of high-resolution seismic profiles from the southeastern continental shelf of Korea reveals that the sedimentary deposits consist of seven seismic units formed during the late Quaternary. These units comprise lowstand, transgressive, and highstand systems tracts. The lowstand systems tract consists of a lowstand prograding wedge (SU1) and a mass flow deposit (SU2) including slumps and slides. The transgressive systems tract contains four seismic units: an ancient beach/shoreface deposit (SU3), a channel-fill deposit (SU4), a transgressive sand layer (SU5), and a transgressive sand ridge (SU6). The highstand systems tract consists of an inner-shelf mud deposit (SU7) derived from the Nakdong and Seomjin rivers during the last 6 ka when sea level was close to the present level.

• Journal of Environmental Health Sciences
• /
• v.47 no.5
• /
• pp.479-485
• /
• 2021

Background: Vibrio vulnificus has been frequently detected in seawater, fish, and shellfish mainly in the coastal areas of Chungcheongnam-do Province. Objectives: This study was conducted to investigate the analyzed biochemical properties, genetic characteristics, and distribution of Vibrio vulnificus isolated from environmental sources in coastal areas of Chungcheongnam-do Province from 2019 to 2020. Methods: A total of 1,510 samples were obtained from six different sites in Chungcheongnam-do Province. Isolated strains from the samples were identified by a VITEK 2 system and MALDI-TOF. Antibiotic susceptibility testing for 85 isolates was done by microdilution minimum inhibitory concentration methods, and 11 isolates were analyzed for 16s rRNA sequences in multiple alignments. Results: Among the 1,510 samples taken during the investigation period, 306 strains were isolated and the detection rate of V. vulnificus was 20.3%. One hundred eighty-eight strains (24.6%) from seawater and 118 strains (15.8%) from mud flats were isolated. It was mainly detected in July (17.3%), August (36.5%), and September (28.8%), and the proportion was 82.0%. Based on the CLSI-recommended breakpoints, V. vulnificus isolates were all susceptible to amoxicillin/clavulanic acid, amikacin, gentamicin, ciprofloxacin and trimethoprim/sulfamethoxazole. However, nonsusceptible isolates to ampicillin, ampicillin/sulbactam, cefazolin, cefoxitin, imipenem, tetracycline and chloramphenicol were identified. In the analysis of the nucleotide sequences for 16s rRNA of V. vulnificus isolates, it was confirmed that mutations frequently occurred between nucleotide number 922 and 952, and 98.2% to 100% nucleotide identities between isolates was verified. Conclusions: The results of this study can be used as a basic data for infection control and prevention of Vibrio vulnificus infection by describing the distribution and characteristics of Vibrio vulnificus strains isolated in coastal areas of Chungcheongnam-do Province.

• Korean Journal of Heritage: History & Science
• /
• v.54 no.4
• /
• pp.4-21
• /
• 2021

The purpose of this study is to examine the names and types of walls constructed in the late Joseon Dynasty in YeonggeonUigwe, a record of construction works of the Joseon Dynasty, and to examine the current status and name of walls constructed in the main hall and the Yeongnyeongjeon Hall of Jongmyo Shrine. The results of the study are as follows. First, the name of the wall can be divided into four types depending on the characteristics, including direction, location, shape, function, material, and complexity, and was used as a compound word in front of the wall. Second, some of the wall types related to the material were found to have differences in the timing of theypes of walls. Since the 18th century, the use of earthen walls has been reduced, and the use of wooden walls and paper walls are often used. Third, the walls of the Jongmyo Shrine were composed of a mud wall and a fireproof wall. A fireproof wall was installed in the main hall, including a pillar, while the Yeongnyeongjeon Hall was installed only between the pillar and the pillar. Fourth, the Gap Wall can be defined as the "wall constructed at the upper part of the chamber used in the construction of the building in Jongmyo." This study is meaningful in that it attempted to clarify the definition of a wall in the late Joseon Dynasty by examining the names and examples of walls used in the late Joseon Dynasty, focusing on walls that lacked research in familiarity.

• Korean Journal of Remote Sensing
• /
• v.37 no.5_1
• /
• pp.1111-1124
• /
• 2021

Mudflats are crucial for understanding the ecological structure and biological function of coastal ecosystem because of its high primary production by microalgae. There have been many studies on measuring primary productivity of tidal flats for the estimation of organic carbon abundance, but it is relatively recent that optical remote sensing technique, particularly hyperspectral sensing, was used for it. This study investigates hyperspectral sensing of chlorophyll concentration on a tidal flat surface, which is a key variable in deriving primary productivity. The study site is a mudflat in Geunso bay, South Korea and field campaigns were conducted at ebb tide in April and June 2021. Hyperspectral reflectance of the mudflat surfaces was measured with two types of hyperspectral sensors; TriOS RAMSES (directionalsensor) and the Specim-IQ (camera sensor), and Normal Differenced Vegetation Index (NDVI) and Contiuum Removal Depth (CRD) were used to estimate Chl-a from the optical measurements. The validation performed against independent field measurements of Chl-a showed that both CRD and NDVI can retrieve surface Chl-a with R² around 0.7 for the Chl-a range of 0~150 mg/m² tested in this study.

• Journal of Marine Life Science
• /
• v.5 no.2
• /
• pp.81-91
• /
• 2020

This study was conducted to find the faunal composition and distribution patterns of macrobenthos where the sand tidal flat around barrier island at Nakdong River estuary in May, 2016 and 2017. The number of species ranged from 31 to 39, and density was from 789 to 1,644 ind.m^-2 during the study period in the three tidal flats. The number of species and density were the highest in the tidal flat of Shinja-do and Jinwoo-do, respectively. The dominant species were Gammaridae unid. in amphipods of crustacea, Scoletoma heteropoda, Scoloplos armiger, Heteromastus filiformis, Prionospio japonica in polychaeta and Batillaria cumingii, Laternula marilina in mollusks from the three tidal flats. The proportion of carnivores such as crustacea and mollusks was higher in the upper part of the tidal flat, and polychaetes of deposit feeders, dominated in the middle and lower tidal flat. Overall, the intertidal macrobenthic communities in the study area showed a high proportion of carnivores. However, the sites where the mud content is high such as muddy sand sites, they showed a higher proportion of surface deposit feeders belonging to tube-builders which contribute to sediment stability. From this study, it seemed that the macrobenthic fauna of the sandy tidal flat at the Nakdong River estuary showed a similar fauna composition and zonal distribution patterns from those in other sandy tidal flats in Korea.

• Journal of Korean Society of Water and Wastewater
• /
• v.32 no.6
• /
• pp.487-497
• /
• 2018

Water quality improvement processes for stagnant area consist mainly of technologies applying vegetation and artificial water circulation, and these existing technologies have some limits to handle pollution loads effectively. To improve the purification efficiency, eco-friendly technologies should be developed that can reinforce self-purification functions. In this study, a multi-functional floating island combined with physical chemical biological functions ((1) flotation and oxidization using microbubbles, (2) vegetation purification and (3) bio-filtration with improved adsorption capacity) has been developed and basic experiments were performed to determine the optimal combination conditions for each unit process. It has been shown that it is desirable to operate the microbubble unit process under conditions greater than $3.5kgf/cm^2$. In vegetation purification unit process, Yellow Iris (Iris pseudacorus) was suggested to be suitable considering water quality, landscape improvement and maintenance. When granular red-mud was applied to the bio-filtration unit process, it was found that T-P removal efficiency was good and its value was also stable for various linear velocity conditions. The appropriate thickness of filter media was suggested between 30 and 45 cm. In this study, the optimal design and operating parameters of the multi-functional floating island have been presented based on the results of the basic experiments of each unit process.

• Korean Journal of Heritage: History & Science
• /
• v.46 no.2
• /
• pp.114-135
• /
• 2013

Among the UNESCO World Heritage Sites, the proportion of natural heritage to cultural heritage is relatively small. In 2007, the "Jeju Volcanic Island and Larva Tubes" was the first one that was designated as an UNESCO World Natural Heritage Site in Korea. The growing Korean geological heritage condition and conservation case studies on management of the geological heritage were examined in this study. Furthermore, the purpose of this study is to show future driving strategy for conservation and improvement plan on our geological heritage. Natural Monuments as a state-designated natural property and Geoparks as a new application system for geological heritage are important to conserve our geological heritage. Public engagement through establishment of visitor centers is definitely needed to improve education and promotion. The study includes field investigation for the "Wadden Sea", an World Natural Heritage Site for a mud flat, interviews with staffs and experts who are responsible for investigating and managing the site. Three factors can likely be attributed to its successful management and conservation policy for the "Wadden Sea". First of all, there is an operation for integrated management system and joint secretariat for research and monitoring. Next, researchers invigorate the visitor centers for promotion and education on geological heritage. Finally, experts and staffs implement various research topics and projects based on a long-range plan. The study was carried out to evaluate the present condition of our geological heritage and to make a proposal as a policy to improve value and conserve them. In conclusion, this study provided future discussion that may help researchers to make a decision on long-term policies for the geological subject of Korean natural heritage.

• Korean Journal of Heritage: History & Science
• /
• v.42 no.3
• /
• pp.132-153
• /
• 2009

A lotus flower pattern of the shape of straight and pointed petals has the forms whose lotus flowers are pointed, and is one of the representative forms of lotus flower pattern of Baekjae along with a round and a triangle protruded style. This style of lotus flower pattern was applied to roof-end tiles, halos of Buddhist images, containers of Buddha's bones, head supports, etc. from the Hanseong period to the Sabi period of Baekjae. However most of lotus flower patterns that remain today were used for the tiles of the Sabi period. Many of them were produced under the influence of the Northern Dynasties and the Southern Dynasties of China, and of Goryeo, which implies the active cultural exchange of Baekjae at that time. Among the present lotus flower patterns of the shape of the straight and pointed petals, that of the earliest time is from Gyeongdang district of Poongnab mud castle and belongs to the mid-fifth century. However there is a higher chance that the gradual subsequent excavation and research will find some tiles of the earlier period and other styles can also be unearthed.