• Journal of Forest and Environmental Science
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• 제38권4호
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• pp.256-262
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• 2022

The timing of seed harvesting is an important decision in the management of seed orchards because it affects seed quality and yield. To investigate the effect of cone harvest time on seed quality and determine the optimal harvesting time, cones were regularly collected in seven times and germination tests were performed at each harvest time in two clonal seed orchards of Chamaecyparis obtusa. As cones developed, the percentage of seed germination increased before cone moisture content began to decrease significantly. The moisture contents of cones were highest at the first collection as 68.3% and 67.3% in Jeju and Gochang seed orchards respectively. At this time, germination speed was slowest, indicating poor seed vigour. The highest germination was found at the second stage in Jeju (36.5%) and at the seventh stage in Gochang (28.6%) seed orchard. The germination speed increased as cone moisture content decreased. Additionally, changes of seed vigour differed among the developmental stages in both seed orchards. Consequently, the optimal cone harvest time of C. obtusa seed orchards in Jeju was early September when high germination percentage was obtained. In Gochang seed orchards, late October was optimal cone harvest time when the germination speed was fast and the cone moisture content decreased.

• 한국지반신소재학회논문집
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• 제13권3호
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• pp.21-30
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• 2014

본 연구에서는 남원 사면현장에서 채취된 화강풍화토를 이용하여 경량 동적콘관입시험기의 국내 사면현장에서 적용성을 조사하였다. 그리고 다짐도와 함수비 변화에 따른 경량 동적콘관입시험을 수행하고, 다짐도, 간극비, 포화도와 콘관입 저항치와의 상관성을 분석하였다. 그 결과로 최적함수비의 건조측에서 함수비 증가와 더불어 관입저항치가 급격히 증가하고 습윤측에서 크게 감소하는 경향을 나타내었다. 또한 물리적 특성과의 상관관계에서 다짐도 및 포화도가 클수록 콘 저항치가 선형적으로 증가하는 것을 확인하였다. 이로 인해 역학특성 변화에 따른 함수비, 간극비, 포화도와 콘관입저항치 사이에 높은 상관성을 보여 사면조사시 경량 동적콘관입시험기의 현장적용이 가능할 것으로 판단된다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.203-206
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• 2003

The liquid limit(LL) test is universally used as a standard test for determining one of the index properties of a clay. There are two methods of determining the LL, Casagrande method and cone penetration method that is fall cone test. The interpretation of the Casagrande method of obtaining the LL is not obvious, but it has been suggested that the fall cone test is essentially a strength test and that the LL test simply ascertains the moisture content at which a clay has a certain standard undrained shear strength. This paper presents a determination of the LL by a single-point method. Results obtained from fall cone that is general method and a single-point method are analyzed by comparison.

• Journal of Biosystems Engineering
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• 제25권3호
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• pp.195-202
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• 2000

This study was conducted to recognize a possibility that cone index can be used as a means of evaluating the tillage workability. Cone indexes were measured every 24 hours after rainfall at the experimental plots, and the rotary and plowing operations were conducted at the same time. The workability was evaluated on a basis of three categories of good, fair and poor depending on the quality of the performed works. Although the workability was affected by many factors such as soil type, moisture content ground slope and weather condition, the duration and amount of rainfall were of most influence. Results of the study showed that a good workability was resulted from the cone indexes greater than an average of 552 kPa for rotary operations and 671 kPa for plowing operations. Fair work was obtained with cone indexes greater than an average of 331 kPa for rotary operations and 459 kPa for plowing operations. The cone indexes less than an average of 171 kPa and 149 kPa resulted in poor workabilities for rotary and plowing operations, respectively. The experimental results may provide a general guideline for evaluating the tillage workability by cone index.

• 한국기계가공학회지
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• 제20권2호
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• pp.8-13
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• 2021

The study for soil has been conducted separately by several areas such as soil mechanics and soil chemistry. Soil is important in terms of prediction of how the plant grow with nutrient requirement. Also, soil is important for machines to work on to solve labor shortage and save farmers from harsh environment during farm work. To meet diverse needs related to soil in agriculture, the soil related study needs to be conducted synthetically. Thus, we tried to obtain the data related to soil chemistry including pH and Electrical Conductivity (EC) with data related to soil mechanics including Cone Index (CI), moisture content, soil classification. Specifically, the condition of the field was set to be cultivated at least for five years continuously at a first step. The soil was taken from 30 sites. CI was obtained using the soil penetrometer and soil classification was conducted using sieve analysis with eight kinds of sieve. The soil was taken on December when is during winter in Korea. There was variation of data including moisture content and CI.

• 한국도로학회논문집
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• 제19권2호
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• pp.17-24
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• 2017

PURPOSES : This study aims to develop a sealant for use in the installation of Weigh-In-Motion (WIM) sensor for asphalt concrete or cement concrete pavements. METHODS : In order to investigate the properties of various sealants that were mixed with latex and carbon fiber, various test methods were adopted, such as bituminous bond strength test, softening point test, and cone penetration test. To evaluate moisture susceptibility, the BBS test was conducted under moist condition. The bond strength ratio (BSR) was calculated based on tensile strength ratio method. RESULTS : The sealant's properties significantly varied according to the amount of latex or carbon fiber. The usage of latex marginally enhanced the cone penetration test result, notwithstanding reduced asphalt content. This implies that the sealant will be proper cold temperature reason. Moreover, the addition of latex and carbon fiber evidently increased the softening point. This indicates that the tendency of the material to flow at elevated temperatures is encountered during service. With the addition of latex and carbon fiber, the moisture susceptibility measured with BSR improved marginally, while the bond strength under dry condition decreased marginally. Sealant F displays the highest bond strength and BSR under limited test conditions. CONCLUSIONS : According to the proportion of latex and carbon fiber mixed, properties of sealant, such as softening point, cone penetration, and BSR varied marginally. This indicates that the sealant has to be applied considering the environmental condition, to improve service life.

• 한국안전학회지
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• 제38권4호
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• pp.39-46
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• 2023

Pine trees, which account for 23% of the forested area of the Republic of Korea, are highly vulnerable to fire in comparison to broad-leaved trees due to the presence of consistent water tube sections throughout the year and resin that is composed of approximately 20% oil. In addition, the pattern of forest fires is determined by weather, topographic conditions, and fluctuation in moisture content. Therefore, when fire breaks out in pine tree forests during the dry season (January to March), it is difficult to extinguish, and it quickly spreads. In this study, the combustion characteristics of pine needles, pine cones, and pine branches in the water tube sections of living pine trees were compared and analyzed in accordance with the moisture content as per the ISO 5660-1. The monthly moisture content was analyzed from January to March, and it was found to be the lowest in March, with 53.6% for pine needles, 51.9% for pine branches, and 10.9% for pine cones. In particular, pine cones were more vulnerable to fire as compared to pine needles and pine branches because their moisture content was more than five times lower than that of pine needles and branches. The ignition time, which affects the speed of flame propagation, was the most rapid in March, and the fastest ignition time was for pine cones, at 19 seconds, followed by 34 seconds for pine needles, and 256 seconds for pine branches. The pine branches were the last to be ignited due to the effect of density, according to the thickness and specific gravity of the specimen. The peak heat release rate, which is a measurable index of fire intensity, was analyzed for pine cones and found to be 184.28 kW/m² , while the mean effective heat of combustion was 19.79 MJ/kg, and the total heat release rate was 39.7 MJ/m² , and these values were higher than those of pine branches and pine needles. Thus, we determined that the flame propagation speed and fire intensity according to the moisture content can be used to evaluate the risk of fire to the water tube section of pine trees. It is suggested that because of the combustion characteristics of the pine cone in March, that is when the forest is most vulnerable to fires.

• 한국농공학회지
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• 제30권2호
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• pp.55-66
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• 1988

This study was conducted to investigate the various engineering properties and correlationshops among the soil constants of alluvial clayey deposits distributed in the bay of Asan and their results are summarized as follows : 1. Grain size distribution of soil was consisted of 12 % of clay, 46-73 % of silt, 2-23 % of sand, and as for the consistency characteristics, 26-36 % of liquid limit, 18-21 % of plastic limit and 6-16 % of plastic index, and so the soil belonging to as a lower plastic nonorganic clay, it's specific gravity was 2,66-2.70, and the location on the plastic chart was approximately above the A-line. Z The natural moisture content and unit weight were 30-43 % and 1.76-1.87 g I cm$_3$, respectively, and according to increment of natural moisture content, the unit weight was decreased, and the initial void ratio and degree of saturation were shown of 0,87-1119 and 92- 100 %, most of saturated. 3. Cone resistance value which was shown 2.4 - 6.5 kg / $cm^2$ was a little lower and it was increased with the depth of layer and shown the formular $q_c=0.7_z+1.32$. 4. Unconfined compression strength was about 0.18-0.43kg /$cm^2$, cu, 0.1-0.22kg / $\psi$, $2-6^{\circ}$ under uu-test condition of triaxial, and CCU, 0.08-0.3 kg/cm , $\psi$, $12-18^{\circ}$ under the condition of cu-test. 5. Pre-consolidation load of characteristics of consolidation was 0.4-0.8 kg / $cm^2$, compression index, about 0.17-0.33. 6. Liquid limit and plastic index were incresased with the increment of clay content but most of alluvial clay was appeared as a normal through non-activity clay soil shown more natural moisture content than liquid limit, and their relationship as follows : LL=0.38( cy+54.8), PI=0.836(LL -17.8), PI =0.468(LL -0.48) 7. The initial void ratio presented correlationship of positive among clay content, natural moisture content and liquid limit, and that of reverse with unit weight, and their results as follws : $e_o=0.024(w_n+0.2)$, $e_o=e_o=0.0003c_y+0.0005 LL+0.0151 W_n+\frac{3.58}{r-t}-1.52$ 8. It was shown that the compression index has correlationship of postive among the clay content, liquid limit, plastic index, natural moisture content and initial void ratio, and their relationships as follows ; $c_c=0.44(e_o-0.47)$, $c_c=0.001$

• Asian-Australasian Journal of Animal Sciences
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• 제29권5호
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• pp.722-730
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• 2016

The carcass traits and meat quality of Hanwoo (Korean native cattle) whose diets were supplemented with direct-fed microbial (DFM) and pine cone extract (PCE) were evaluated. Twenty head of Hanwoo steers were divided equally into four groups and for a period of 6 months were given different diets: One group was fed a basal diet as control (CON), the other three groups were fed a basal diet supplemented with DFM-1%, DFM+PCE-1% and DFM+PEC-3%, respectively. DFM+PCE3% diet resulted the lowest carcass quality grade. The loins of DFM-1% contained higher moisture and lower fat than did the loins from the CON group. The crude protein content of DFM+PCE-3% group was significantly higher than that of the other groups. The water holding capacity and Warner-Bratzler shear force of the DFM+PCE-1% and 3% groups were lower than those of the CON and DFM-1% groups. The DFM-1% and 3% groups contained lower saturated fatty acid, higher unsaturated fatty acid, mono-unsaturated fatty acid, and poly-unsaturated fatty acid than did CON and DFM+PCE 1% group. Moreover, the n6:n3 ratios of DFM-1% and DFM+PCE-1% and 3% groups were slightly lower than that of the CON group. Thus we concluded that DFM and PCE supplementation resulted healthier Hanwoo beef with lower fat content and n6:n3 ratio.

• 한국환경농학회지
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• 제17권1호
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• pp.59-64
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• 1998

The environmental problem of the rural area has been accelerated in soil as well as water. Soil contamination is usually caused by improper operation of landfills, abandoned mine fields, accidental spills, and illegal dumpings. Once soil contamination is initiated, pollutants migrate and may cause groundwater contamination which takes much effort for remediation. Early detection, therefore, is important to prevent further contamination. Electrical resistivity method was used to detect soil contamination, but it was not effective to the heterogeneous condition. Static cone penetrometer test (CPT) has been used widely to investigate geotechnical properties of the underground. In this study, electrical resistivity method and CPT are combined to improve the applicability of it. The pilot test was performed to examine the variation of electrical resistivity with different soil minerals and pore fluid characteristics. Soil samples used were poorly graded sand, silty sandy soil, and weathered granite soil. For all the cases, electrical resistivity decreased with increasing of moisture content. Soil mineral also affected the electrical resistivity significantly. Above all, leachate addition in the pore fluid was very sensitive and caused decreasing of electrical resistivity markedly. It implies that electrical resistivity method can be applied to investigate pollutant plume effectively. This is specially sure when the sensors contact the contaminated soils directly. The CPT method involves cone penetration to the ground, therefore, underground contamination around the cone could be investigated effectively even for heterogeneous condition as it penetrates if electrical resistivity sensors are attached on the cone.