• Korean Journal of Weed Science
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• v.17 no.3
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• pp.281-287
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• 1997

Growth and anatomical responses of rice and barnyardgrass(Echinochloa crus-galli) to oxyfluorfen were examined under various growing conditions in a greenhouse. With foliar application at 0.08kg ai/ha 7 days after seeding or transplanting, oxyfluorfen completely reduced the shoot and root growth of barnyardgrass under all growing conditions. However, oxyfluorfen reduced the growth of direct seeded and transplanted rice by 0~64% and 0~12%, respectively. Phytotoxic effect on rice growth, with respect to plant height and shoot fresh weight, was more pronounced under water(53~63%) than under dry-condition(16~33%), and in broadcast-seeded(34~62%) than in drill-seeded rice(16~33%). Anatomical changes of epidermal and vascular bundle sheath cells of rice leaves were not induced by oxyfluorfen, but mesophyll cells were partially ruptured and total leaf thickness was reduced. Oxyfluorfen, however, constricted and ruptured mesophyll and vascular bundle sheath cells and severely reduced leaf thickness of barnyardgrass under all growing conditions examined. These anatomical changes were more severe under dry- than under water-seeded condition.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.20
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• pp.152-162
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• 1975

Five barley varieties were compared under six 1evels of nitrogen fertilization and two methods of cultural management, conventional and drill seeding. The increase in grain yield and nitrogen content of the leaves showed a significant linear regression from added increaments of nitrogen in Haganemugi and Olbori, particulary under drill seeding. The other varieties resulted in various degrees of lodging and no significant increases in yield. The spike number per square meter was the major component of yield, but when the spike number per square meter was sufficient, 1000 grain weight was equally as important as a component of yield.

• Economic and Environmental Geology
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• v.45 no.4
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• pp.397-406
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• 2012

During the 2nd Ulleung Basin Gas Hydrate Drilling Expedition (UBGH2) in 2010, gas-hydrate-bearing sediment cores were recovered at 10 drill sites. Base, on Infrared (IR) thermal image and grain-size analysis of the cores, three distinct types of gas hydrate are classified: Type I (fracture-filling in mud layers), Type II (disseminated in mud layers), and Type III (pore-filling in sand layers). Types I and II gas hydrates occur in mud as discrete veins, nodules or disseminated particles. Type III fills the pore spaces of the sand layers encased in mud layers. In this case, the sand content of hosting sediments shows a general linear relationship with gas hydrate saturation. The degrees of temperature anomalies (${\Delta}T$) from IR images generally increase with gas hydrate saturation regardless of gas hydrate occurrence types. Type I is dominantly found in the sites where seismic profiles delineate chimney structures, whereas Type II where the drill cores are composed almost of mud layers. Type III was mainly recovered from the sites where hemipelagic muds are frequently intercalated with turbidite sand layers. Our results indicate that gas hydrate occurrence is closely related to sedimentological characteristic of gas hydrate-bearing sediments, that is, grain size distribution.

• Journal of the Mineralogical Society of Korea
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• v.17 no.1
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• pp.99-114
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• 2004

Mineralogical characteristics of fracture-filling minerals from deep borehole in the Yuseong area were studied for the radioactive waste disposal project. There are many fracture zones in the deep drill holes of the Yuseong granite, which was locally affected by the hydrothermal alteration. According to the results of hole rock analysis of drill core samples, $SiO_2$ contents are distinctly decreased, whereas $Al_2$$O_3$ and CaO contents and L.O.I. values are increased in the -90 m∼-130 m and -230 m∼-250 m zone, which is related to the formations of filling minerals. Fracture-filling minerals mainly consist of zeolite minerals (laumontite and heulandite), calcite, illite ($2M_1$ and 1Md polytypes), chlorite, epidote and kaolinite. The relative frequency of occurrence among the fracture-filling minerals is calcite zeolite mineral > illite > epidote chlorite kaolinite. Judging from the SEM observation and EPMA analysis, there is no systematic change in the texture and chemical composition of the fracture-filling minerals with depth. In the study area, low temperature hydrothermal alteration was overlapped with water-rock interactions for a long geological time through the fracture zone developed in the granite body. Therefore the further study on the origin and paragenesis of the fracture-filling minerals are required.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.503-510
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• 2020

Concrete is one of the most widely used materials as the shielding structures of a nuclear facilities. It is also the most generated radioactive waste in quantity while dismantling facilities. Since the concrete captures neutrons and generates various radionuclides, radiation measurement and analysis of the sample was fulfilled prior to dismantle facilities. An HPGe detector is used in general for the radiation measurement, and effective correction factors such as geometrical correction factor, self-absorption correction, and absolute detector efficiency have to be applied to the measured data to decide exact radioactivity of the sample. Correction factors are obtained by measuring data using a standard source with the same geometry and chemical states as the sample under the same measurement conditions. However, it is very difficult to prepare standard concrete sources because concrete is limited in pretreatment due to various constituent materials and high density. In addition, the concrete sample obtained by core drill is a volumetric source, which requires geometric correction for sample diameter and self absorption correction for sample density. Therefore in recent years, many researchers are working on the calculation of effective correction factors using Monte carlo simulation instead of measuring them using a standard source. In this study we calculated, using Geant4, one of the Monte carlo codes, the correction factors for the various diameter and density of the concrete core sample at the gamma ray energy emitted from the nuclides ¹⁵²Eu and ⁶⁰Co, which are the most generated in radioactive concrete.

• Journal of Preventive Medicine and Public Health
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• v.21 no.2 s.24
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• pp.357-364
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• 1988

By implementing epoch-making policies for industrial promotion, the national economy has made a remarkable development. As a result of such economic growth, industrial accidents and occupational diseases have become a serious problem in Korean society. In the presidential order for the execution of the Korean Labor Standard Law, neuritis and other diseases stemming from health impairments due to vibrations in industrial processes are designated to be dealt with as vibration diseases. In the case of vibration disease, industrial accident compensation is not effectively paid. In order to investigate the vibration hazards of rock-drill operation, the authors studied the subjective symptoms and performed physical function tests on a total of 79 persons (vibration exposed group) who used rock-drills, and 39 persons (control group) who did not use rock-drills at anthracite mines. The results of the physical function test were as follosws : 1. The right hand was more affected by white finger than the left hand. 2. Independent variables such as duration of rock-drill operation, age, drinking and smoking were indentified as statistically significant factors for the occurrence of white finger. 3. In the pain sense threshold, the group with Raynaud's phenomenon showed a statistically higher level than that of the control group. 4. The skin temperature of the group with Raynaud's phenomenon was lower than that of the control group. The recovery time of skin temperature aftr cooling was delayed compared with the value of the control group.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.2
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• pp.114-121
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• 1997

Latex Coated Urea(LCU) was compared with ordinary urea under different methods of application in terms of N use efficiency and yield of rice, 1995 and 1996. The study was carried out on Jeonbug silty clay loam, in Honam Agricultural Experiment Station. The fertilizer treatments involved (1) conventional application of urea (44kg N/ha at transplanting, 33kg N/ha at five leaves stage, 33kg N/ha. (4) 55kg N/ha at transplanting and 33kg N/ha as urea at panicle initiation stage, and (5) without N. It was found that by combining LCU(as basal application) and urea(as topdressing at panicle initiation stage), at the rate of 80% of conventional rate with ordinary urea is most effective for the saving of N and increasing the use efficiency of N by rice. It was, however, observed that the efficacy of LCU was affected by the temperature during the growth of rice.

• Advances in environmental research
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• v.6 no.3
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• pp.159-171
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• 2017

A successful oil well drilling depends largely on a good mud Program. During drilling, mud provides sufficient hydrostatic pressure, removes drill cuttings and cools drill bits. Mud additives are always required to provide sufficient hydrostatic pressure to ensure borehole stability. Barium Sulphate ($BaSO_4$) also known as barite is the prevalent weighting material but there is needed to develop local materials to augment the use of Barite. The present search is concerned on the early Carboniferous succession exposed in Um Bogma Formation, west central Sinai, Egypt as a new weighting agent in drilling fluids. The increases in the cost of drilling fluids and a shortage of using barite have introduced the locale dolomite as alternative weighting materials. The rheological properties of mud drilling samples weighted by local dolomite samples are being examined and investigated to know its potential to be used as a weighting material in drilling mud. Two mud samples were prepared which comprised of fresh water, caustic soda, bentonite and the weighting material. The weighting materials are added to achieve the required density. The first sample: Water-based mud with commercial barite of density between 10.00 lb/gm and 18.00 lb/gm. The second sample: Water-based mud with dolomite of density between 10.00 lb/gm and 18.00 lb/gm. These samples were analyzed and the density, rheological properties, aging of barite and dolomite and solid contents were investigated. At 10.00 lb/gm, the yield point of dolomite was $20.00lb/100ft^2$ and barite $22.00lb/100ft^2$ while the 10 second gel strength of dolomite was $30.00lb/100ft^2$ and $22.00lb/100ft^2$ for barite. Similarly, little difference was observed in plastic and apparent viscosities. At 10.00 lb/gm, the plastic and apparent viscosities of dolomite were 8.00 cp and 20.00 cp while barite was 8.00 cp and 24.00 cp. The result show that dolomite mud sample gave a little higher yield point and gel strength than barite mud sample. Therefore, dolomite has the potential to be used as weighting material in drilling mud in place of barite thereby enhancing the local content initiative of the government. When dolomite is sourced locally and used it will reduce overall mud and drilling costs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.259-266
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• 2020

In this study, required drill bits and excavation methods were developed for an uneven drilling method that can solve the problem of performance degradation of rock bolts. The developed drill bit's excavation performance was verified using rock with a strength of 100 MPa or more. In addition, for the relative evaluation of the uneven excavation method, experimental specimens were prepared for models with and without irregularities, and tests were performed. As a result of the experiment, the model with unevenness exhibited an average critical draw resistance of 801.6 kN, which is about 1.7 times the value of 468.7 kN for the model without unevenness, thus confirming the effect sufficiently. Therefore, it is expected that the resistance performance will significantly increase despite an increase in the uneven hole diameter of 20 mm. In the future, the results of this study could be used as basic data when performing other studies using numerical analysis models and performance verification through experiments to obtain an optimized rock forming method.

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.22-30
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• 1995

Responses of Pospam-injected chestnut and pine trees to drill wound were examined. Pospam was injected into the stem by just filling up the drill wound in September 10, 1993. The diameter of the injection wound were 0.5 and 1cm. DBH of chestnut trees and pine trees injected were 10, 15, 20 and 10, 20, 30cm, respectively. The results of tree response were examined in June, 1994. None of them showed any symptom of decay by the time. However, sapwood under the bark was remarkably discolored. The discoloration was more severe in 1cm-injection wound than in 0.5cm one. The severity of discoloration was not differed between species and among DBH applied. The sapwood split was longer in 1cm-injection wounded trees than in 0.5cm trees and longer in chestnut trees than in pine trees. From the split, callus grew out and almost closed the splits. In the trunk injection tested, the damage was mare severe in 1cm injection wound of chestnut trees than in any other combination.