• Geophysics and Geophysical Exploration
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• v.9 no.4
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• pp.279-290
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• 2006

The borehole radar methods used to tunnel detection are mainly classified into borehole radar reflection, directional antenna, crosshole scanning, and radar tomography methods. In this study, we have investigated the feasibility and limitation of each method to tunnel detection through case studies. In the borehole radar reflection data, there were much more clear diffraction signals of the upper wings than lower wings of the hyperbolas reflected from the tunnel, and their upper and lower wings were spreaded out to more than 10m higher and lower traces from the peaks of the hyperbolas. As the ratio of borehole diameter to antenna length increases, the ringing gets stronger on the data due to the increase in the impedance mismatching between antennas and water in the boreholes. It is also found that the reflection signals from the tunnel could be enhanced using the optimal offset distance between transmitter and receiver antennas. Nevertheless, the borehole radar reflection data could not provide directional information of the reflectors in the subsurface. Direction finding antenna system had a advantage to take a three dimensional location of a tunnel with only one borehole survey even though the cost is still very high and it required very high expertise. The data from crosshole scanning could be a good indicator for tunnel detection and it could give more reliable result when the borehole radar reflection survey is carried out together. The images of the subsurface also can be reconstructed using travel time tomography which could provide the physical property of the medium and would be effective for imaging the underground structure such as tunnels. Based on the results described above, we suggest a cost-effective field procedure for detection of a tunnel using borehole radar techniques; borehole radar reflection survey using dipole antenna can firstly be applied to pick up anomalous regions within the borehole, and crosshole scanning or reflection survey using directional antenna can then be applied only to the anomalous regions to detect the tunnel.

• Korean Journal of Ichthyology
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• v.31 no.4
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• pp.222-234
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• 2019

Fish community characteristics and habitat aspects of endangered species, Pseudopungtungia tenuicorpa and Acheilognathus signifer were investigated in the Hwayangcheon Stream of Songnisan National Park, a tributary of the Hangang River, Korea from April to October 2018. During this period, there were 29 species of 8 families collected from 11 survey stations using kick nets, cast nets long bag set nets. The dominant and subdominant species were Zacco koreanus (38.81%) and Rhynchocypris oxycephalus (16.64%), respectively. The next most abundant species were Z. platypus (14.28%), Pungtungia herzi (6.92%), Hemibarbus longirostris (4.52%), Pseudogobio esocinus (3.51%), A. signifer (2.31%) and P. tenuicorpa (1.90%). Among the fish collected, 18 species (62.1%) were Korean endemic species. Endangered species were A. signifer, P. tenuicorpa and Gobiobotia brevibarba. From upstream to downstream, the dominance index has gradually decreased, but number of species and individuals, diversity and evenness has gradually increased. Also, river health (index of biological integrity) is assessed as good (St. 1~8) and very good (St. 9~11). Fish communities were divided into four sections by the similarity index based on species and their numbers, i.e., upper section (St. 1~2, 4~5), upper-middle section (St. 3, 6), middle section (St. 7~9) and lower section (St. 10~11). Endangered species, Pseudopungtungia tenuicorpa inhabited in mostly lower section (St. 10~11) with rock and boulder bottoms, and age groups in April estimated from total length indicated that the 44~61 mm group is 1 year old, the 66~81 mm group is 2 years old, the 88~99 mm group is 3 years old, and the 104~107 mm group is more than 4 years old. Also, endangered species, A. signifer inhabited in middle-lower section (St. 7~11) with boulder and cobble bottoms and slow velocity, which the place inhabited by water plants. Meanwhile, their age structure in April estimated from total length indicated that the 30~43 mm group is 1 year old, the 48~58 mm group is 2 years old, the 62~77 mm group is 3 years old, and the 84~100 mm group is more than 4 years old. The sex ratio of female (47) to male (42) was 1 : 0.89.

• Journal of Environmental Science International
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• v.20 no.11
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• pp.1417-1423
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• 2011

For evaluating the effect of various organic fertilizer ratios on the Spiraea${\times}$bumalda 'Gold Mound' growth, a container green wall system experiment was conducted in a greenhouse at Konkuk university. The experimental planting grounds were prepared with different organic fertilizer ratios ($A_1L_0$, $A_8L_1$, $A_4L_1$ $A_2L_1$ and $A_1L_1$) and with drought tolerance and an ornamental value Spiraea${\times}$bumalda 'Gold Mound' was planted. The change in soil moisture contents, plant height, number of branches, number of dead leafs, number of leaf, number of shoots, length of node, length of leaf, width of leaf, root-collar caliper, chlorophyll contents and survival rate were investigated from April to Jun 2010. 1. The result of soil moisture contents was analyzed with weight unit in the container green wall system during the dry summer season. The soil moisture contents were significantly enhanced in the container green wall system in increasing order as the amount of fertilizer level increased $A_1L_1$ > $A_2L_1$ > $A_4L_1$ > $A_8L_1$ > $A_1L_0$. 2. Compared to the control treatment (amended soil with 100% + organic fertilizer 0%) application, the highest plant growth was observed in the treatment of $A_2L_1$(amended soil with 67% + organic fertilizer 13%) application. However, the differences between the organic fertilizer ratio treatments of $A_1L_1$, $A_4L_1$, $A_8L_1$, and the $A_1L_0$ organic fertilizer application were mostly not significant. 3. The survival rate increased with the increasing application of organic fertilizer, but in the control treatment (amended soil with 100% + organic fertilizer 0%) application all the plants died. Experimental results from the presented study clearly demonstrated that the organic fertilizer improved the survival rate more than the Spiraea${\times}$bumalda 'Gold Mound' growth at different levels of organic fertilizers. This strain can be utilized as a plant growth application in living wall systems during the dry summer season. Therefore, Spiraea${\times}$bumalda 'Gold Mound' is expected to be a highly valuable shrub for the green wall system if it should be considered in integration with stormwater retention or as a soil conditioner for increasing soil water contents in planting ground.

• Journal of the Korean GEO-environmental Society
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• v.15 no.5
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• pp.47-56
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• 2014

In winter season, the pore water inside the ground freezes and thaws repetitively due to the cold air temperature. When the freezing-thawing processes are repeated on the ground, the change in soil particle structure occurs and thus the damage of the infrastructure may be following. This study was performed in order to investigate the stiffness change of soils due to the freeze-thaw by using elastic waves. Sand-silt mixtures are prepared with in the silt fraction of 40 %, 60 % and 80 % in weight and in the degree of saturation of 40 %. The specimens are placed into the square freezing-thawing cell by the temping method. For the measurement of the elastic waves, a pair of the bender elements and a pair of piezo disk elements are installed on the cell, and a thermocouple is inserted into soils for the measurement of the temperature. The temperature of the mixtures is decreased from $20^{\circ}C$ to $-10^{\circ}C$ during freezing, is maintained at $-20^{\circ}C$ for 18 hours, is gradually increased up to the room temperature of $20^{\circ}C$ to thaw the specimens. The shear waves, the compressional waves and the temperature are measured during the freeze-thaw process. The experimental result indicates that the shear and the compressional wave velocities after thawing are smaller than those of before freezing. The velocity ratio of after thawing to before freezing of shear wave is smaller than that of the compressional wave. As silt fraction increases from 40 % to 80 %, the shear and compressional wave velocities are gradually increased. This study suggests that the freezing-thawing process in unsaturated soil loosens the soil particle structure, and the shear wave velocity reflects the effect of freezing-thawing more sensitively than the compressional wave velocity.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.223-230
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• 2015

The objective of this study is to identify the radionuclide distribution in public water by carrying out the analysis of artificial radionuclides($^{134}Cs$, $^{137}Cs$, $^{239+240}Pu$), natural radionuclide($^{210}Pb$) and TOC in the lake Euiam sediment in Chuncheon, South Korea. The $^{134}Cs$ concentration in all lake sediments showed below MDA values, and the $^{137}Cs$ concentration in lake sediment were ranged from MDA to $8.79Bq{\cdot}kg^{-1}-dry$. The $^{137}Cs$ concentrations in surface sediment were reported to be 2.4 to $4.2Bq{\cdot}kg^{-1}-dry$. The lowest concentration of $^{137}Cs$ was reported at St. 4 and the highest concentration was reported at St. 3, respectively. The $^{239+240}Pu$ concentration in lake sediment were ranged from 0.049 to $0.47Bq{\cdot}kg^{-1}-dry$. The lowest concentration was reported at St. 2 and the highest concentration was reported at St. 3. The correlation(r) between the $^{239+240}Pu$ concentration and $^{137}Cs$ concentration in lake sediment presented higher values (0.54 to 0.97) and this suggests the behavior and origin of $^{137}Cs$ is identical to the $^{239+240}Pu$ in the sediment. The $^{134}Cs$ concentration below MDA value and the $^{239+240}Pu/^{137}Cs$ ratio(mean value of 0.041) indicated that the artificial radionuclides in the sediment were originated from global fallout by the atmospheric testing of nuclear weapons conducted by former USSR and U.S.A, but not from the Fukushima Daiichi NPP accident. The sedimentation rate derived from $^{210}Pb$ age-dating method at St. 2 is calculated to be $0.31{\pm}0.06cm{\cdot}y^{-1}$. This value is similar to the value ($0.41{\pm}0.05cm{\cdot}y^{-1}$) estimated from the $^{137}Cs$ maximum peak produced from early 1960's. The content of TOC in lake Euiam sediments varied from 0.20 to 13.01%. While the highest correlation between TOC and $^{137}Cs$ concentration in the sediment were found at St. 1, the others presented the low correlation.

• Culinary science and hospitality research
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• v.18 no.5
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• pp.267-278
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• 2012

The purpose of this study was to investigate the quality characteristics of Sulgidduck made with commercial dry rice powder, providing an optimal milk ratio and soaking time for dry powder in water to make Sulgidduck using dry rice powder. The Sulgidduk samples with dry rice powder were prepared with two soaking times (0, 30 min) and different amounts of milk (0, 20, 40, 60%), and analyzed for moisture content, Hunter's color value, texture characteristics and sensory evaluation. The moisture content of the samples ranged from 36.37% to 39.80% and the highest moisture quantity was showed in the group with 20% of milk and 30min of soaking time(SM20). The L-value was the highest in the group with 20% of milk and 0min of soaking time(M20). The b-value was increased with the amount of milk and soaking time increased, showing the highest in the group with 60% of milk and 30min of soaking time(SM60). TPA showed that SM20 had the lowest hardness and the highest adhesiveness. Chewiness, gumminess and cohesiveness were the highest in the group with 60% of milk and 0min of soaking time(M60). Based on quantitative descriptive sensory evaluations, the score of white color and moistness was showed high in the group with 0% of milk and 0min of soaking time(M0), and white powder on the surface was shown the most in the group with 20% of milk and 30min of soaking time(SM20). The score of moistness, springiness and chewiness were highest in the group with 20% of milk and 0min of soaking time(M20). Sulgidduk made with 20% of milk and 0min of soaking time(M20) was the most preferable in color, flavor, taste, and overall acceptability.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.2
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• pp.232-237
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• 1994

Changes of volatile components in modified oleoresin red pepper during cooking at high temperature were investigated. Dried red pepper was milled to 100mesh of size particle and oily compounds were extracted by reduced pressure steam distrillation. The rest part was reextracted and concentrated. The extracts were combined. The same volume of water and 4% of polyglycerol condensed ricinoleate (PGDR) were added to the combined extract, and emulsified to make oleoresin red pepper 119 volatile compounds were separated from the dried red pepper and oleoresin and 35 components were identified in both samples. The major flavor compounds were identified to be 2-methoxy-phenol, 2, 6-bis(1, 1-dimethylethyl)-4-methyl-phenol, 1, 4-dimethylbenzene, thylbenzene, 1, 2-benzenedicarboxylic acid, 2-methoxyl-4-methylphenol, 4-ethyl-2-methoxy-phenol, and 5- methyl-2-furancarboxyaldehyde, and their transferal from raw red pepper to oleresin was low. 93 voltilie compounds were isolated after 3 hours cooking at 100 and 82 volitile compounds were separated after that at $150^{\circ}C$. Degeneration of volatile compounds was peculiarly proportional to the temperature of cooling. Capsaicin was relatively stable during cooking and remaining ratio after cooking at 100 and $150^{\circ}C$ was 84.7% and 73.3%. respectively. Oleoresin from red pepper had a little antioxidation effect at $100^{\circ}C$ cooking, but, antioxidation effect at $150^{\circ}C$ cooking was not shown due to degradation of capsaicin.

• Journal of Korean Society of Forest Science
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• v.77 no.3
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• pp.259-268
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• 1988

For the purpose of examining the effects of simulated acid rain on nutrient contents of plant tissues in Pintos densiflora seedlings and Forsythia koreana rooted cuttings, the experimental design of randomized block arrangement with three replications was implemented in the experimental field of Yesan National Agricultural Junior College. One-year-old Pinus densiflora seedlings and Forsythia koreana cuttings were planted in the pots filled the mixed soils(nursery soil : forest soil of siliceous sandy loam=1 : 1 v/v) in the early spring of 1986. The regime of artificial acid rain, in terms of spray frequency per month and spray amount at single treatment per plot, was simulated on the basis of climatological data averaged from 30 years records. Simulated acid rain(pH 2.0, pH 4.0, and pH 5.5 as control) containing sulfuric and nutric acid in the ratio of 3 : 2(chemical equivalant basis) diluted with ground water were treated on the experimental plants under condition of cutting off the natural precipitation with vinyl tunnel, during the growing season(May 1 to August 31) in 1986. The results obtained in this study were as follow : (1) As for the nitrogen contents in plant tissues, P. densiflora increased significantly in one-year-old stembranch and root tissues, and F. koreana increased significantly in leaf and root tissues, as the pH levels of acid rain decreased. (2) The available phosphate contents in root tissues of P. densiflora, and in leaf and root tissues of F. koreana were significantly decreased, as the pH levels of acid rain decreased. (3) $K_2O$, CaO and MgO contents in plant tissues were significantly decreased in the both species as the pH levels decreased. And the effects of acid rain on F. koreana were higher than those of P. densiflora. (4) Sulfur contents of plant tissues in the both species were increased at pH 2.0 treatment. There were significant differences among three acid rain treatments in leaf and root tissues of P. densiflora, and in all parts of F. koreana. (5) In the effects of simulated acid rain on the both species and the tested soils, in general, F. koreana revealed higher sensitiveness than P. densiflora, and the lower pH levels of simulated acid rain were treated, the more sharp reaction was showed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.5
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• pp.208-215
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• 2005

The 10mm diameter aggregates made of clay, carbon and $Fe_2O_3$ were prepared to investigate the mechanism of black core formation. The specific gravity, absorption rate, percent of black core area, fracture strength, total Fe analysis, and XRF were measured at various compositions, sintering temperatures, sintering times, sintering atmospheres, and sintering methods. Small addition of $Fe_2O_3$ did not affect physical properties of the aggregates; however, the percent of black core area increased with increasing carbon contents and increasing sintering temperature. Specific gravity of the aggregates decreased and the water absorption ratio increased with increasing percent of black core area. The aggregates sintered at oxidation atmosphere showed clear border between shell and black core area. Hence, the aggregates sintered at reduction atmosphere showed only black core area in the cross-section of the aggregates. The specific gravity of the aggregates sintered at reduction atmosphere increased with increasing carbon contents and that was the lowest of all comparing other aggregates sintered at different atmospheres. Adsorption rate increased with increasing carbon contents at all atmospheres. The fast sintered aggregates showed lower specific gravity, higher absorption rate, and more black core area than the normally sintered aggregates. It was turned out that the aggregates having more black core area showed higher fracture strength than that of aggregates with no black core area. From the total Fe analysis, the concentration of Fe and FeO was higher at black core area than at shell. Because the concentration of $Fe_2O_3$ in the shell was higher than other area, the color of the shell appeared red. It was also turned out from the XRF analysis that carbon was exist only at black core area.

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.645-653
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• 2004

The purpose of this study was to compare and analyze the cognitive levels of 11th grade students and those required in high school chemistry I textbooks standardized by the 7th national education curriculum. For this study, the cognitive development stages of 456 11th grade students were surveyed using short-version GALT (group assessment of logical thinking). Furthermore, 15 basic concepts were extracted from the contents on water and air, 2 units in chemistry I order to analyze the cognitive levels necessary for understanding high school textbooks, using CAT (curriculum analysis taxonomy). The results showed that 52.5% of the surveyed 11th grade students reached the formal operational level, 28.3% transitional levels, and 19.5% concrete operational levels. 68.9% of the academic high school students and 6.6% of the technical high school students reached the formal operational levels, and the ratio of formation was very different in each logics. As a result of the analyzing the cognitive levels needed for understanding chemistry I textbook contents, in spite of a change in national education curriculum, there were no great change in cognitive levels required by scientific concept except some inquiry activities. The cognitive levels in high school chemistry I textbooks by the 7th national education curriculum appeared higher than the cognitive levels of 11th grade student, but cognitive levels of inquiry activities were similar to the cognitive levels of the students. Chemistry teachers thought of chemistry I textbooks by the 7th national education curriculum as desirable because scientific concepts were reduced and a lot of real life materials were adapted. However, they pointed out a problem of difference in contents levels compared with chemistry I textbooks because scientific concepts were greatly reduced in chemistry I textbooks. The cognitive levels required in chemistry I textbooks still appeared higher than those of the students. Consequently, various teaching and learning methods and materials will have to be developed to be suitable for the students' cognitive levels.