• Journal of Korean Society of Forest Science
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• v.105 no.3
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• pp.315-320
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• 2016

This study was carried out to establish a management plan for urban forest trails with analysis of trail damage types and soil physicochemical properties on 3 urban forest parks in Jinju, Gyeongnam-do. We found that soil hardness was significantly higher in forest trails than forest area at 0 cm and 5 cm at a significance level of 0.05. However, we could not find any significant differences for other soil properties. For the trail damage types, the most common types were as follows: trail expansion (66%), trail erosion (59%), side road (57%), and trail boundary erosion and root exposure (41%). The results showed no difference in most of these types between the trails and forest area, indicating that the forest area might be damaged as well as the trails. Priority should be given to prepare measures that prevent soil compaction from overcrowded hikers.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.883-889
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• 2014

It is generated for cavitation erosion due to the local static boiling by pressure differentials in high speed rotating fluid environment. The cavitation is influenced by various elements such as pressure, velocity, temperature, pH of fluid and medium. In particular, the damage of material is accelerated due to the electrochemical corrosion by $C1^-$ and cavitation erosion due to cavities in seawater. In this paper, hence, it investigated for martensite stainless steel the damage behavior with applied current density and cavitation time in natural seawater solution. Less damage depth at the cavitation condition was observed than static condition as a result of galvanostatic experiment. Furthermore, it was shown that dramatic increase of weightloss, damage rate and damage depth after 3 hour of cavitation test.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.56-63
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• 2016

This experiment was compared and analyzed between the original surface paint through chloride penetration, neutralization, freeze-thaw and chemical corrosion resistance measuring internal structure and volume of voids in order to evaluate the effect of increase in durability of the newly modeled nano synthesized polymer paint painted on concrete surface which results improvement on air permeability to increase the durability of concrete structures. The test result of measuring volume of void and inner structure, concrete, spreaded with nano synthesized polymer paint, showed decreasing trend of pore volume in the range of less than $0.1{\mu}m$ and more than $0.3{\mu}m$. Also, using an electron microscope inside showed tightness of hydration texture. Chloride penetration depth of concrete, painted with nano synthesized polymer paint, was decreased more than 92% compared to non-painted concrete and 70% with water-based epoxy painted concrete. Especially, chemical corrosion resistance test set with aqueous solution of 5% sulfuric acid, non-painted concrete and water-based epoxy painted concrete showed weight loss of 4% after dipping for 12 days. On the other hand, concrete painted with nano synthesized polymer paint showed 1.7% weight loss under the same condition. Also, it showed great result of appearance under the criteria of Tsivilis et al.

• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.385-395
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• 2011

The adjustment processes and responses of a series of mining pits by sand or gravel mining were investigated by laboratory experiments. The filling processes of the two pits were affected by the bars developed in the upstream of the channel. However, the bars were not developed and the bed was degradated in the downstream of the pits due to little sediment flow, which was trapped in the pits. The submerged angle of repose in the pits was nearly constant when the pits were being filled. After the filling processes of the pits were finished, the pit was speedily filled with sediment, and the bed was aggradated and migrated with speed. However, the angle of repose decreased. As the distance between the upstream pit and the downstream pit increased, the bed of the pit downstream was tailcutted and degradated. The migration speed of the pit decreased. However, the dimensionless pit depth increased as the distance between the pits increased. The dimensionless pit depth increased with time.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.308-313
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• 2009

유역에서 물의 평균체류시간은 강우에 의해 토양에 강우 등으로 인해 수분이 침투하여 유출되기까지 소요되는 평균 시간이며, 침식, 식생분포, 유출기작 등을 지배하는 수문학적 과정을 이해하는데 중요한 요소이다. 물의 평균체류시간을 산정하는 대표적인 방법인 방사성 동위원소에 의한 추적자법은 계산과정이 복잡하고 많은 비용이 들면서도 간접적인 방법임으로, 본 연구에서는 토양수분의 거동을 관측해 산지사면에서 물의 평균체류시간을 산정하는 보다 직접적인 방법을 고안하였다. 토양수분의 측정을 위해 광릉 국립수목원에 위치한 산림 소유역에 토양 수분 측정장비인 TDR을 설치하고 1년 동안 2시간 간격으로 깊이별 측정을 수행하였다. 토양수분을 이용해 산정된 물의 체류시간은 대상유역의 불투수 지하면에 가까워질수록 상승하는 경향을 보였고 강우가 집중된 여름에 가장 짧은 것으로 나타났다. 실험에서 얻어진 평균체류시간은 기존의 화학적 방법을 통해 산정된 값과 유사한 경향을 보였는데 이러한 결과들은 토양수분의 측정과 분석을 통한 방법이 방사성 동위원소를 이용한 방법보다 더욱 효율성 있는 측정을 할 수 있다는 것을 나타낸다.

• Korean Journal of Environment and Ecology
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• v.6 no.1
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• pp.55-71
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• 1992

Visitor's impact on environmental deterioration of and around trail was studied in Hallasan National Park, Korea in 1990. Width of tread and width of bareland beside trail were correlative positively to user's density, negatively to height of vegetation and slope, respectively. Depth of tread was correlative highly to width of tread and width of bareland beside trail. Areal deterioration by visitors almost took place on subalpine zone. Total damaged area was kestimated to be 121, 000$m^2$ and the damaged area more severe than impact rating class 4 reached about 72.000$m^2$, respectively. Ten types of deterioration of and around trail were discovered and total volume of erosion to be recovered was estimated to be about 62.000$m^2$.

• Geophysics and Geophysical Exploration
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• v.20 no.3
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• pp.146-162
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• 2017

Multibeam and seismic data in the northwestern part of the Ulleung Basin were analyzed to study stratigraphy and evolutionary history of submarine canyon. A detailed analysis reveals that the sedimentary sequences in this area consist of four stratigraphic units separated by erosional unconformities. On the continental slope, these units are dominated by well-stratified facies with some slope failures, whereas these units show well-stratified and chaotic facies toward the basin floor. Generally, the sediment thickness is relatively thin on the slope, whereas thick sediment accumulation occurs on the base of slope and basin floor. Based on seismic characteristics and distribution, the deposition of each units are well correlated with the evolutionary history of the submarine canyon. Unit 1 directly overlying the acoustic basement has thin sediment layer on the slope, whereas its thickness gradually increase toward the basin floor. Compared to other units, Unit 2 is relatively thick accumulations on the slope and contains some slope failures related to faults systems. The mass transport sediments due to slope failures, mainly deposited on the base of slope as a submarine fan. The width and depth of submarine canyon increase due to dominant of the erosional process rather than the sediment deposition. Unit 3 is thin accumulation on the slope around the submarine canyon. Toward the basin floor, its thickness gradually increases. Unit 4 is characterized by thin layers including slides and slumps on the slope, whereas it formed thick accumulations at the base of slope as a submarine fan. The increase in the width and depth of submarine canyon results from the dominant of the erosional process and slope failures around the submarine canyon. Consequently, the formation of sedimentary units combined with the development of submarine canyon in this area is largely controlled by the amounts of sediment supply originated from slope failures, regional tectonic effects and sea-level fluctuations.

• Journal of Korean Society of Forest Science
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• v.100 no.3
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• pp.476-482
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• 2011

As part of studies on the reduction of forest trails degradation caused by high users density, this study was carried out to investigate soil physical properties of forest trails of Gyeongnam Domain in Mt. Jiri, Southeast Korea. Since the forest were opened for leisure trailing in 2008, the average soil erosion amounts per a square meter on the forest trails were $0.0015m^3$ from Inweol to Gumgeo, $0.0018m^3$ from Dongang to Suchol, and $0.0027m^3$ from Suchol to Chungam for 3 years. But, from Chungam to Agyang, the erosion was almost not occurred because it was recently opened. The soil hardness in 5 cm depth was significantly higher than in 10 cm depth. It indicates that intensive soil compaction by users has mainly affected in 5 cm soil depth until now on. In three forest trails compacted intensively, the porosity of 0-7.5 cm soil layer was down to 1.4-1.5 times compared to that in 2008. In additions, the bulk density was up to 1.6-3.1 times compared to the controls, which were not opened to users. As a result, the degradation caused by high users density would keep occurring on the three forest trails unless any counterplans are considered for the degradation reduction. At the moment, users distribution to other forest trails and long-term sabbatical years would be the most effective counterplans to keep from users gravitation on the three forest trails.

• Journal of Korean Society of Forest Science
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• v.89 no.1
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• pp.24-32
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• 2000

We investigated the patterns of soil horizon evolution and its water distribution on three different forest stands covered with Larix leptolepis, Pinus koraiensis, and Qercus mongolica on the Experimental Forest of Kyunghee University, located in Kwangju, Kyunggi-Do. Compared to the properties of depths of O and A horizons evolved on the Pinus koraiensis stand, the depths of O and A horizons on the forest stands of Larix leptolepis and Qercus mongolica were shallower, indicating that the soil horizon were deeply influenced by geographical characteristics, its erosive and sedimentary distinction, vegetation cover and its population density. And the bulk densities of the sites selected were lower in the high slope gradient than that in the lower slope gradient at the same depth of soil profile. Therefore, the changes of the soil bulk densities were closely related to the soil organic matter and the vertical transport of soil particle throughout soil depths. On the other hand, the bulk density and organic matter content in soil can influence the water transport phenomena, resulting in decrease of the hydraulic conductivity as the increase in the bulk density, while the organic matter can not affect the hydraulic conductivity on the soil surface layer. For a rainfall infiltration characteristics from a lysimeter experiment established on the stand of Larix leptolepis, the bulk density and slope gradient strongly influenced the vertical transport of water, as well as the lateral movement of rainfall. Conclusively, the characteristics of water movement and distribution in the forest stand can be determined not by the geographical factor such as slope gradient but also by the bulk density and organic matter content remained in soils.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.217-223
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• 2010

This study was conducted to reclassify Dongsong series based on the second edition of Soil Taxonomy and to discuss the formation of Dongsong series distributed on the lava plain at Cheolweon in Korea. Morphological properties of typifying pedon of Dongsong series were investigated, and physico-chemical properties were analyzed according to Soil Survey Laboratory Methods Manual. The typifying pedon of Dongsong series has brown (7.5YR 4/2) silty clay loam Ap horizon (0-16 cm), brown (7.5YR 4/2) silty clay loam BA horizon (16-22 cm), brown (7.5YR 4/2) silty clay Bt1 horizon (22-50 cm), reddish brown (5YR 5/4) silty clay Bt2 horizon (50-92 cm), and brown (7.5YR 4/3) silty clay loam Bt3 horizon (92-120 cm). It occurs on lava plain derived from baslt materials. The typifying pedon has higher bulk density than 0.90 Mg $m^{-3}$. That can not be classified as Andisol. But it has an argillic horizon from a depth of 22 to more than 120 cm, and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. It can be classified as Ultisol, not as Andisol or Alfisol. It has aquic conditions for some time in normal years in one or more horizons within 50 cm of the mineral soil surface, redoximorphic features between a depth of 25 cm, and a depth of 40 cm from the mineral soil surface, and redox concentrations, and 50%or more redox depletions with chroma of 2 or less in the matrix within the upper 12.5 cm of the argillic horizon. Therefore it can be classified as Aquult. It has episaturation, and keys out as Epiaquult. It has 50% or more chroma of 3 or more in one or more horizons between a depth of 25 cm from the mineral soil surface, and a depth of 75 cm. It can be classified as Aeric Aquult. Dongsong series have 35%or more clay at the particle-size control section, and have mesic soil temperature regime. Therefore they can be classified as fine, mesic family of Aeric Epiaquults, not as fine, mesic family of Typic Epiaqualfs. The Quarternary volcanic activities occurred in Jeju Island, Ulrung Island, Baekryeong Island, Cheolweon area, and Mt. Paekdu et al. in the Korean Penninsula. Most of them belong to the central eruption type, but Cheolweon area may be of the fissure eruption type. Dongsong series occur on Cheolweon lava plains derived from basaltic materials. Most soils distributed in Jeju Island, and derived from mainly pyroclastics are developed as Andisols. But Dongsong series distributed in Cheolweon lava plains which have a relatively dry climate and derived from basaltic materials are developed as Ultisols.