화강암질풍화토의 (花崗岩質風化土) 역학적 성질에 관한 연구 - 전단강도의 (剪斷强度) 영향요소와 견밀도에 (堅密度) 대하여 -

조희두 ( Hi Doo Cho ) 한국산림과학회 1984 한국산림과학회지 Vol.66 No.1

It is very important in forestry to study the shear strength of weathered granitic soil, because the soil covers 66% of our country, and because the majority of land slides have been occured in the soil. In general, the causes of land slide can be classified both the external and internal factors. The external factors are known as vegetations, geography and climate, but internal factors are known as engineering properties originated from parent rocks and weathering. Soil engineering properties are controlled by the skeleton structure, texture, consistency, cohesion, permeability, water content, mineral components, porosity and density etc. of soils. And the effects of these internal factors on sliding down summarize as resistance, shear strength, against silding of soil mass. Shear strength basically depends upon effective stress, kinds of soils, density (void ratio), water content, the structure and arrangement of soil particles, among the properties. But these elements of shear strength work not all alone, but together. The purpose of this thesis is to clarify the characteristics of shear strength and the related elements, such as water content (w_o), void ratio(e_o), dry density (γ_d) and specific gravity (G_s), and the interrelationship among related elements in order to decide the dominant element chiefly influencing on shear strength in natural/undisturbed state of weathered granitic soil, in addition to the characteristics of soil hardness of weathered granitic soil and root distribution of Pinus rigida Mill. and Pinus rigida × taeda planted in erosion-controlled lands. For the characteristics of shear strength of weathered granitic soil and the related elements of shear strength, three sites were selected from Kwangju district. The outlines of sampling sites in the district were: average specific gravity, 2.63 ∼ 2.79; average natural water content, 24.3 ∼ 28.3%; average dry density, 1.31 ∼ 1.43 g/㎤, average void ratio, 0.93 ∼ 1.001 ; cohesion, 0.2 ∼ 0.75 ㎏/㎠ ; angle of internal friction, 29°∼ 45° ; soil texture, SL. The shear strength of the soil in different sites was measured by a direct shear apparatus (type B; shear box size, 62.5 × 20㎜; σ, 1.434㎏/㎠ ; speed, 1/ 100㎜/min.). For the related element analyses, water content was moderated through a series of drainage experiments with 4 levels of drainage period, specific gravity was measured by KS F 308, analysis of particle size distribution, by KS F 2302 and soil samples were dried at 110±5℃ for more than 12 hours in dry oven. Soil hardness represents physical properties, such as particle size distribution, porosity, bulk density and water content of soil, and test of the. hardness by soil hardness tester is the simplest approach and totally indicative method to grasp the mechanical properties of soil. It is important to understand the mechanical properties of soil as well as the chemical in order to realize the fundamental phenomena in the growth and the distribution of tree roots. The writer intended to study the correlation between the soil hardness and the distribution of tree roots of Pinus rigida Mill. planted in 1966 and Pinus rigida × taeda in 199 to 1960 in the denuded forest lands with and after several erosion control works. The soil texture of the sites investigated was SL originated from weathered granitic soil. The former is situated at Pyo¨ngchangri, Kyo¨m-myo¨n, Kogso¨ng-gun, Cho¨llanam-do (3.63 ㏊; slope, 17°∼ 41° soil depth, thin or medium; humidity, dry or optimum; height, 5.66/3.73 ∼ 7.63 m.; D.B.H., 9.7/8.00 ∼ 12.00 ㎝) and the Latter at changun-long Kwangju-shi (3.50 ㏊; slope, 12°∼ 23° soil depth, thin; humidity, dry; height, 10.47/7.3 ∼ 12.79 m ; D.B.H., 16.94/14.3 ∼ 19.4 ㎝).The sampling areas were 24quadrats (10m × 10m ) in the former area and 12 in the latter expanding from summit to foot. Each sampling trees for hardness test and investigation of root distribution were selected by purposive selection an

사방시공지에 (砂防施工地) 있어서 리기다소나무의 수근의 (樹根) 분포에 미치는 토양견밀도의 (土壤堅密度) 영향

조희두 ( Hi Doo Cho ) 한국산림과학회 1982 한국산림과학회지 Vol.56 No.1

Soil harness represents such physical properties as porosity amount of water bulk density and soil texture. It is very important to know the mechanical properties of soil as well as the chemical in order to research the fundamental phenomena in the growth and the distribution of tree roots. The writer intended to grip soil hardness by soil layer and also to grasp the root distribution and the correlation between soil hardness and the root distribution of Pinus riguda Mill. planted on the denuded hillside with sooding works by soil layer on soil profile. The site investigated is situated at Peongchang-ri 13, Kocksung county Chon-nam Province. The area is consisted of 3.63 ha having on elevation of 167.5-207.5 m. Soil texture is sandy loam and parant rock in granite. Average slope of the area is 17。-30。. Soil moisture condition is dry. Main exposure of the area is NW or SW. The total number of plots investigated was 24 plots. It divided into two groups by direction each 12 plots in NW and SW and divided into three groups by the position of mountain plots in foot of mountain, in hillside, and in summit of mountain, respectively. Each sampling tree was selected as specimen by purposive sampling and soil profile was made at the downward distance of 50cm form the sampling tree at each plot. Soil hardness, soil layer surveying, root distribution of the tree and vegetation were measured and investigated at the each plot. The soil hardness measured by the Yamanaka Soil Hardness Tester in mm unit. the results are as follows: 1) Soil hardness increases gradually in conformity with the increment of soil depth. the average soil indicator hardness by soil layer are as follows: 14.6mm in I-soil layer (0-10cm in depth from soil surface), 16.2mm in II-soil layer (10-20cm in depth from soil surface), 17.2 in III--soil layer (20-30cm), 18.3mm in IV-soil layer(30-40cm), 19.8mm in V-soil layer(4.50mm). 2) The tree roots (less than 20mm in diameter) distribute more in the surface layer than in the subsoil layer and decrease gradually according to the increment of soil depth. The ratio of the root distribution can be illustrated by comparing with each of five soil layers from surface to subsoil layer as follows: I-soil layer:31%, II--soil layer:26%, III-soil layer:18%, IV-soil layer:12%, V-soil layer:13%, 3) Soil hardness and tree root distribution (less than 20mm in diameter) of Pinus rigida Mill. correlate negatively each other; the more soil hardness increases, the most root distribution decreases. The correlation coefficients between soil hardness and distribution of tree roots by soil layer are as follows : I-soil layer;-0.3675(at the 10% significance level), II-soil layer;-0.5299(at the 1% significance level), III-soil layer;-0.5573(at the 2% significance level), IV-soil layer;-0.6922(at the 5% significance level), V-soil layer;-0.7325(at the 2% significance level). 4) the most suitable range of soil hardness for the growth of Pinus rigida Mill is the range of 12-14.9mm in soil indicator hardness. In this range of soil indicator hardness, the root distribution of this tree amounts to 41.8% in spite of 33% in soil harness and under the 20.9mm of soil indicator hardness, the distribution amounts to 93.2% in spite of 82% in soil hardness. Judging from above facts, the roots of Pinus rigida can easily grow within the soil condition of 20.9mm in soil indicator hardness. 5) The soil layers are classified by their depths from the surface soil

벽체의 (壁體) 변위와 토압분포와의 관계에 대한 연구 - 비점성토의 (非粘性土) 지표면이 경사질 경우

조희두 ( Hi Doo Cho ) 한국산림과학회 1973 한국산림과학회지 Vol.17 No.1

This study was performed for the purpose of determining the effects of distribution of the lateral earth pressure in the case of sloping backfills of being consisted of the idealized cohesionless fragmental masses. The displacements were classified as eight types by D_UBROVA (by patterns). B type among these has its turning point at the top of the wall, moves outwardly and is significant to gravitational structure because of its foundation elasticity which causes displacement. Therefore, it might be surely acknowledged that the resultant, fromula; E=l/2*rH²{sin(u-ε)cos(α+ε)}/cos(u+α)*cot(u+p)(t/㎥), is appropriate for applying it to the designing of the sand-catch dams. The results obtained are as follows: 1. Lateral earth pressure is proportional to the square of the wall heights. 2. The coefficient(K) is directly proportional to the sloping of backfill surface and inversely proportional to the displacement. 3. The distribution of the pressure looks like parabola, curve of second order (Fig. 5, b). 4. The distribution of the pressure strength looks like that of hydrostatic pressure (Fig. 5, c).

통리 해수욕장 녹지대 조성에 관한 연구 (Ⅱ) - 곰솔 해안방재림의 (海岸防災林) 수관량 (樹冠量) 및 토양분석 , 식재기반평가 (植栽基盤評價) 및 녹지대계획 -

조희두 ( Hi Doo Cho ) 한국산림과학회 1988 한국산림과학회지 Vol.77 No.3

Tong-ri beach has not enough vegetation to be enjoyed by the sea bathers and to be satisfied with preventing the disaster-damages, but mixed forest near the beach can work its funtions and the old forest of Pirus thunbergii P_(ARL.) near the beach do a Little. Therefore it is very urgent to plant more trees near the beach for bathers and disaster-damage prevention. This study was carried out for planning an afforestation, with reporting upon the crown amounts and soil properties of disaster-damage prevention forests of P. thunbergii P_(ARL.) planted on the coast sand dunes in 1970 and 1976, and with reporting upon the valuation on soil properties of the lands near the beach in order to set the afforestation site. The results are as follows : 1. In disaster-damage prevention forests, crown surface area and crown volume became increasingly greater in proportion to the height. To D.B.H., crown volume also became increasingly greater in proportion, but crown surface area was directly pruportional. 2. In comparison to sail characteristics of sand dune, those of the forests were in large quantity in OM, T-N and avail. SiO₂, and almost in the same in avail. P₂O_5, but in small quantity in exchangeable canons : K, Ca, Mg and Na. 3. EC, Cl and pH were in small value in the forest soils, but CEC was in large value in those soils. 4. Above facts showed that the forests fulfill their functions for preventing disaster-damages and improve their soil properties. 5. The forests have naturally been thinned up to 34% in 17 years and 39% in 11 years, and one can easily pass through the forest(planted in 1910), because of its sufficient clear-length(2.71m) and its space to pass, 6. A plan for afforestation was oracle nut after judging several sites by the evaluation cm the soil properties and considering the best relaxation and the prevention of the various disaster-damages upon which were reported in the last issue. 7. Afforestation should be kept for maintaining its appropriate density for best relaxation and disaster-damage prevention.

통리해수욕장 녹지대조성에 관한 연구 (Ⅰ) - 사구지주변의 (砂丘地周邊) 재해요인분석 -

조희두 ( Hi Doo Cho ) 한국산림과학회 1988 한국산림과학회지 Vol.77 No.2

This study is carried out for analyzing the factors causing several disasters occurring around beach area in order to set a plan for an afforestation which will fulfill its function as facilities for prevention of disasters and for relaxation around beach resort at Tong-ri, Pokil-myon, Wando-gun. The results are as follows : 1. The main wind direction was summer was SE. 2. The first class in the rate of frequency of the hourly average wind speed and the instantaneous wind speed in summer were 2.1-3.0m/sec (29.2%) and 1.1-2.0m/sec (30.6%) respectively. 3. The particle sizes of the dune sands was a little small (82.5% in 0.125 to 0.25㎜, DS_(50)=0.178㎜). 4. The mineral composition and the chemical components were as follows : The main mineral : Quartz The accessary minerals : Calcite, Feldspars(Orthoclase), Sericite. The chemical components : SiO₂ ; 75.6%. Al₂O₃ ; 8.1%, CaO ; 7.76%, Ign. loss ; 6.8%. MgO ; 0.23%, K₂O ; 0.72%, Na₂O ; 0.41%, Fe₂O₃ ; 0.32%. 5. The threshold friction velocity equation for the diameter class of the dune sands was y=4.191x^(0.221) 6. The amount of floating salt was maximum at the point of 65m away from beach line, dropped abruptly at 135m and remained almost same on its way to the inland. The equation of the amount of floating salt was y=28.181 × (-0.369^x). 7. The amount of extracted salt(33%) in seawater in summer was the same as the one of the nearest seawater of Korea.

호우량의 추정에 관한 일고찰

조희두 ( Hi Doo Cho ) 한국산림과학회 1974 한국산림과학회지 Vol.23 No.1

After lasting heavy storm, the overfow from the top of soil saving dam may follow if the outlet is not precisely designed and it causes great damages as a result. Therefore, the peak rate of flood must be premeditated at the time of dam construction and many kinds of erosion control measures should also be constructed to protect against the effects of oveflow causing the damages. In this paper, the daily maximum amounts of precipitation from 1904 to 1972 are used as samples of this statistical analysis for the previous purpose and studying local ranges are limited the number of areas to two; Pusan and Mokpo area, because other areas can not give the data of more than 69 years. Normal distribution, as follows, is used for this statistical study. P(X) = ∫f(x)dx x: daily maximum amount X: maximum of x P(X): probability to exceed X value The estimates, which are the resultants of statistical analysis, can be locally compared with the real values (daily maximum amounts) by diagram, whether the former truly coincides with the latter. As a result, statistical method canot be used for the premeditation of the amount as well as timing of heavy storms because the estimates donot coincide with the real values in this analysis.

삼림 토양에서 분해된 유기물의 미세형태학적 및 SEM 에 의한 관찰

조희두(Hi Doo Cho),안기완(Ki Wan An) 한국산림과학회 2002 한국산림과학회지 Vol.91 No.5

N/A

우리나라 남부지역 화강암질 삼림토양의 SEM 과 TEM 에 의한 관찰

조희두(Hi Doo Cho),안기완(Ki Wan An) 한국산림과학회 2001 한국산림과학회지 Vol.90 No.5

To understand the weathering processes of the soil by submicroscopic method is very important to realize the properties of the soils. In this study soil formation processes show every steps to the changes in chemical and mechanical properties and the submicroscopic characteristics of soil weathering on the profiles of forest soils derived from granite in southern part of Korea. Fecal pellets(SEM) are given a full detail of the positive activities of the forest soil animals; mainly invertebrates in the O horizon and the E horizon. External shapes of fecal pellets have been divided into five groups : spherical, ellipsoidal, cylindrical, platy and threadlike. But doughnutlike form of fecal pellets is observed in this study. The soluble and suspended materials in the soils move downwards by percolation from the A horizon to the B or the BC horizons, and result in the illuviation cutans(SEM) on the ped surface of the lower horizon and deposited stack of kaolinite. Illuviated cutans are deposited on the ped surface even in the depth of 312cm in the BC horizon as well as the Bt horizon and comprise of fine silt, coarse clay and fine clay. A lot of halloysites are observed on the cutan surface. Halloysite formation from feldspars has been well known but a lot of hallyosite formation are observed in this study. The formation were predicted by Jackson(1962), inferred by Wada and Kakuto(1983a, b) and proved evidently by Cho and Mermut(1992a, b). This also suggests that halloysites in the soils derived from granite are formed a lot from ferruginous chlorites. The release of Fe from the chlorite structure are significant pedogenic processes and newly formed Fe oxides imparted a red color to the soils. The iron oxides particles, which are ejected and recrystalized, aggregate thickly on the edge of the ferruginous chlorites, and this indicates the release of structural Fe from weathered chlorites. Hematites and goethites are frequent in the fine clay in this soils.

하도 내 달뿌리풀 서식에 대한 바닥막이의 영향 분석

안영상 ( Young Sang Ahn ),조희두 ( Hi Doo Cho ),서정일 ( Jung Il Seo ),김석우 ( Suk Woo Kim ),전근우 ( Kun Woo Chun ) 한국산림과학회 2003 한국산림과학회지 Vol.92 No.3

In analyzing of stream grade-stabilization structures for Phragmites japonica inhabitation in channel bed of the Bukbang stream, a branch of the Han River. The upper has narrow width of stream and gradient of stream is urgent comparatively and that bed material consists of boulder stone and gravel, fine-grained sediment area was not found. These featured differed in the middle of the stream and the low of the stream , Bed material of the middle and the low is finer than the upper stream and width of stream is wider, fine-grained sediment area was found. The P. japonica was apparent in the community for the channel bed of Bukbang stream, and Salix gracilistyla was growing in part of the P. japonica community surrounding area. When the stream grade-stabilization structures series were constructed over the whole channel bed(L’/L=1) on model experiment, the F.A. value was decreased approximately 1/11 compare with non-work(L’/L=0). The efficiencies of the stream grade-stabilization structures series on the channel width, after the construction of stream grade-stabilization structures series on the whole channel bed(L’/L= 1), flow channel width was decreased to about 0.71 times compare with non-work(4`/t=0) . Stream grade-stabilization structures are confirmed that the structures influence to make up bed invasion condition and inhabit such as P. japonica.

대상벌채한 리기다소나무 조림지의 토양미소절지동물 분포에 관한 연구

오광인(Kwang In Oh),조희두(Hi Doo Cho),안기완(Ki Wan An),장석기(Seog Ki Jang),정진철(Jin Chul Chung),김춘식(Choon Sik Kim) 한국산림과학회 2001 한국산림과학회지 Vol.90 No.3

This study was carried out to investigate composition and distribution of the soil microarthropods in Pinus rigida plantations following strip-cutting from May 1998 to Apil 1999. The results of this study were as follows; 1. The individuals of soil microarthropods found during the research periods were 181, 904 and were identified into 21 orders in 7 classes. The classes were Arachnida, Insecta, Malacostra, Pauropoda, Diplopoda, Chilopoda and Symphyla. 2. The population density of the soil microarthropods was 82,962 individuals at the control area, 62,688 individuals at the reserve area and 36,254 individuals at the cutting area. The microarthropods in the control area were 2 times higher than those in the cutting area. 3. Although the major dominant taxa, Acari and Collembola, decreased in densities at the cutting area, the density reduction in Acari was higher than that in Collembola. This resulted in the increase of Collembola in terms of the relative abundance at the cutting area. 4. Among the total soil microarthropods, Arachnida was 59.74%, followed by Insecta of 39.82%. Such two groups comprise 99.56% of soil microarthropods. 5. According to the relative population density, Acari was 99.18% in Arachnida and 59.25% in the total and Collembola 93.99% in Insecta and 37.42% in the total. Therefore, individuals of Acari and Collembola was 96.67% of the total individuals. And the next abundant groups were Hymenoptera (0.95%), Diptera (0.64%) and Pseudoscorpiones (0.39%). 6. The population density of the soil microarthropods fluctuated seasonally, showing the bimodal pattern, being high in fall and spring. The highest density occurred in November and the lowest in July.