• Korean Journal of Environment and Ecology
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• v.23 no.6
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• pp.545-552
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• 2009

This study was conducted to provide basic information for development of habitat-based conservation strategies of biological diversity in agricultural ecosystem. The carabid beetle assemblages were examined at four kinds of habitats(levee, dike, forest patch remnants and streamside) from three differently stressed areas located in Paltan-myun, Hwaseong city, Korea: agricultural and forest area(site 1), industrial area(site 2), and residential area(site 3). Pitfall trap samplings were carried out 39 times from November 2000 to November 2002. Our study's findings were that the composition of carabid beetle fauna, dominance species, and pattern of carabid beetle assemblage were different among the habitats. The similarity index was highest between two levees in site 2 and 3, and lowest between hillock in site 2 and streamside in site 3, and that among habitats fragmented by road with high traffic was lower than that among any other habitat types. So, we could know that agricultural land use respectively do an important role in diversity conservation and networking. These findings will be used to establish the land use and management plans in the aspects of conservation of biodiversity.

• Progress in Medical Physics
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• v.12 no.1
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• pp.1-8
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• 2001

Diamond thin films were synthesized by a chemical vapor deposition (CVD). Raman spectrum showed the diamond line at 1332 $cm^{-1}$ / and x-ray diffraction pattern exhibited a strong (111) peak of diamond. The scanning electron microscopy analysis showed that the CVD diamond thin film was grown to be unepitaxial crystallites with pyramidal hillocks. A wavelength-resolved thermoluminescence (TL) of the CVD diamond thin film irradiated with X-rays showed one peak at 430 nm around 560 K. The glow curve of the CVD diamond thin film produced one dominant 560-K peak that was caused by first-order kinetics. Its activation energy and the escape frequency were calculated to be 0.92 ～ 1.05 eV and 1.34 $\times$ 10$^{7}$ sec$^{-1}$ , respectively. The emission spectrum at 560 K was split into 1.63-eV, 2.60-eV, and 3.07-eV emission bands which is known to be attribute to silicon-vacancy center, A center, and H3 center, respectively.

• Journal of the Korean Vacuum Society
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• v.6 no.1
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• pp.61-68
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• 1997

We examined the dependence of the growth of undoped InP epilayer by chloride vapor phase epitaxy on the growth temperature and on the $PCl_3$molar fraction. The growth temperature was varied from $620^{\circ}C$ to $650^{\circ}C$ and the $PCl_3$molar franction from $2.5{\times}10^{-2}$ to $4.5{\times}10^{-2}$. The undoped InP epilayer with hillock free surface was obtained at the growth temperature of $640^{\circ}C$ and at the PCl$_3$molar fraction of $3.0{\times}10^{-2}$. The surface morphology was improved with a decrease of the PCl$_3$molar fraction. The carrier concentration measured by Hall and ECV was less than $1{\times}10^{14}cm^{-3}$. The resistivity of the undoped InP epilayer, measured by using four probe method, showed a high value of <$3.0{\times}10^6{\Omega}\textrm{cm}$.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.1
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• pp.3627-3641
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• 1975

The Government is trying to increase total food grain yield to meet national self sufficiency by means of increasing unit yield as well as extending crop land, and this year he set the target of 321,000 hectare of forest to clear for cropping. This study was carried to investigate the most efficient method of clearing hillock by bulldozer, and successful method to develope yielding potential of newly cleared land in short term. Since the conventional land clearing method is just earth leveling and root removing neglecting top soil treatment, the growth of crop was poor and farmer tends not to care the land. The top-soil-furrowing method is applied through out this study, that is advantageous especially for the land having shallow top soil and low fertility like Korean forest. In this study, various operating method were tried to find out most efficient method separately in connection with the land slope less than 25 percent and over, and several fertilizing methods to develop yielding potential. The results are as follows; 1) For the natural land slope utilization method, applicable to the land having less than 25 percent slope, reverse operating was more efficient than using forward gear of bulldozer. The operating time was 3 hour 32 minutes and 36 seconds using forward gear was 2 hour 32 minutes and 30 seconds for reverse gear operation per 1,000 square meter. 2) Bulldozer having angle blade adjustment needed 7hr 15min. for constructing of terrace per 10a compaire with the one having angle & tilt adjustment needed 6hr 4min for same operations. Specially there is significant difference for operation time of first period (earth cutting) such as bulldozer having angle blade adjustment needed 3hr 56min compaired with the one having angle & tilt adjustment 3hr 59min. In construction of terrace, the bull-dozer having tilting and angle blade adjustment was most suitable and performed efficiently. 3) For the fertilizer application treatment, the grass (Ladino clover) yield in first year was almost same as ordinary field's in the plot applied(N.P.K+lime+manure) while none fertilizer plot showed one tenth of it, and (N.P.K.+lime) applied plot yielded on third. 4) The effect of different land clearing method to yield showed significant difference between each treatment especially in the first year, and the conventional method was the lowest. In the second year, still conventional terracing plot yielded only half of ordinary field while the other plots showed as same as ordinary field's. 5) The downward top soil treatment plot showed most rapid improvement in soil structure during one year physio chemically, it showed increase in pH rate and organic composition, and the soil changed gradually from loam to sand-loam and the moisture content increased against the pF rate, and it gives good condition to grow hay due to the increase of field water capacity with higher available water content. 6) Since the soil of tested area was granite, the rate of soil errosion was increased about 2 to 5 percent influencing in soil structure more sand reducing clay content, and an optimum contour farming method should be prepared as a counter measure of errosion.

• International Journal of Oral Biology
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• v.31 no.4
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• pp.113-118
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• 2006

In the primary sensory neuron of the mesencephalic trigeminal nucleus (MTN), the peripheral axon supplies a large number of annulospiral endings surrounding intrafusal fibers encapsulated in single muscle spindles while the central axon sends only a few number of synapses onto single ${\alpha}-motoneurons({\alpha}-MNs)$. Therefore, the ${\alpha}-{\gamma}$ linkage is thought to be very crucial in the jaw-closing movement. Spike activity in a ${\gamma}-motoneuron\;({\gamma}-MN)$ would induce a large number of impulses in single peripheral axons by activating many intrafusal fibers simultaneously, subsequently causing an activation of ${\alpha}-MNs$ in spite of the small number of synapses. Thus, the activity of ${\gamma}-MNs$ may be vital for modulation of jaw-closing movements. Independently of such a spindle activity modulated by ${\gamma}-MNs$, somatic depolarization in MTN neurons is known to trigger the oscillatory spike activity. Nevertheless, the trafficking of these spikes arising from the two distinct sources of MTN neurons is not well understood. In this short review, switching among multiple functional modes of MTN neurons is discussed. Subsequently, it will be discussed which mode can support the ${\alpha}-{\gamma}$ linkage. In our most recent study, simultaneous patch-clamp recordings from the soma and axon hillock revealed a spike-back-propagation from the spike-initiation site in the stem axon to the soma in response to a somatic current pulse. The persistent $Na^+$ current was found to be responsible for the spike-initiation in the stem axon, the activation threshold of which was lower than those of soma spikes. Somatic inputs or impulses arising from the sensory ending, whichever trigger spikes in the stem axon first, would be forwarded through the central axon to the target synapse. We also demonstrated that at hyperpolarized membrane potentials, 4-AP-sensitive $K^+$ current ($IK_{4-AP}$) exerts two opposing effects on spikes depending on their origins; the suppression of spike initiation by increasing the apparent electrotonic distance between the soma and the spike-initiation site, and the facilitation of axonal spike invasion at higher frequencies by decreasing the spike duration and the refractory period. Through this mechanism, the spindle activity caused by ${\gamma}-MNs$ would be safely forwarded to ${\alpha}-MNs$. Thus, soma spikes shaped differentially by this $IK_{4-AP}$ depending on their origins would reflect which one of the two inputs was forwarded to the target synapses.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.3
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• pp.124-127
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• 2005

It is demonstrated that the annealing process for Ti in-diffusion to z-cut $LiNbO_3$ at temperature lower than the curie temperature in a platinum (Pt) box can cause a ferroelectric micro-domain inversion at the +z surface and Li out-diffusion, therefore which should be avoided or suppressed for waveguide type periodically poled lithium niobate (PPLN) devices. The depth of the inversion layer depends on the Ti-diffusion conditions such as temperature, atmosphere, the sealing method of $LiNbO_3$ in the Pt box and crystal orientation is experimentally examined. The result shows that the polarization-inverted domain boundary appears at the only +z surface and its thickness is about $1.6{\mu}m$. Also, for the etched $LiNbO_3$, surface the domain shape was observed by the optical microscope and atomic force microscopy (AEM), and distribution of the cation concentrations in the $LiNbO_3$ crystal by the secondary ion mass spectrometry (SIMS).

• Korean Journal of Plant Taxonomy
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• v.38 no.4
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• pp.573-582
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• 2008

We report a newly found natural habitat of Abeliophyllum distichum in mountainous slope range of Yeongdong-gun, Chungbuk Province. Abeliophyllum distichum Nakai is one of the Korean monotypic endemic species. Natural growth habitats of this species have been recorded from seven sites up to now, and all of the natural habitats are located in middle (Chungbuk Prov.) and middle west (Jeonbuk Prov.) parts of South Korea. Among the previously recorded seven natural habitats, six sites have been designated as Korean national monuments and protected with in situ conservation. New natural habitat of A. distichum is located on northwest slope of stiff hillock area beside the small stream, Seolgye-ri, Yeongdong-eup, Yeongdong-gun, Chungbuk Province. Total growing area is nearly $3,000 m^2$. It is 10-25 cm in soil depth and pH 5.0-6.5 in soil acidity in that area. And many of A. distichum are clustered with 2-5 individuals extended by stoloniferous asexual reproduction. And the total numbers of A. distichum are about 700 individuals with only typical white flowers, and the ratio between pin type and thrum type is 37% and 63%, respectively. The huge population of A. distichum is growing with Quercus mongolica-Fraxinus rhynchophylla association in a mixed forest, and it shows high affinity with Stephanandra incisa, Ligustrum obtusifolium, Euonymus alatus for. ciliatodentatus, and Smilax sieboldi.