• Korean journal of applied entomology
• /
• v.22 no.2 s.55
• /
• pp.98-105
• /
• 1983

The rapid increase in cases of insect resistance to insecticides indicates that the contribution of present chemical control practices inevitably leads to exhaustion of available insecticide resources against key insect species. Now the problem of insecticide resistance exists worldwide among insects and mites affecting field crops and animals including human beings, ranging from minimal or absent in some developing countries, where use of insecticides has been low, to extremely severe in many developed countries. Since the occurrence of insect resistance to insecticides was firstly recognized in 1908, the increase in recent decades has been almost linear and now the number of species of insects and acarines in which resistant strains have evolved have been increased to a total of 432. Of these, $261(60\%)$ are agricultural importance and $171(40\%)$ of medical/veterinary importance. The phenomenon of insecticide resistance is asserting itself as the greatest challenge to effective chemical control of many important insect pests. Resistance of insects to insecticides has a history of nearly 80 years, but its greatest increase and its strongest impact have occurred during the last 40 years following the discovery and extensive use of synthetic organic insecticides and acaricides. The impact of resistance should be considered not only in terms of greater cost of pest control due to increased dosages and number of applications but also in terms of the ecological disruption of pest-beneficial species density relationships, the loss of investment in the development of the insecticides concerned, and socio-economic disruption in agricultural communities. Despite its grave economic consequences, the phenomenon of insecticide resistance has received surprisingly little attention in Korea. Since the study of insecticides started firstly in 1963, many entomologists have been concerned with this study. According to their results, some of the rice pests and some of the mites on orchard trees, for example, have developed worrisome level of resistance in several areas of this peninsula. With many arthropods, considerable advances in the developed countries have been made in the study of the biochemical and physiological mechanisms of resistance. Progress involves the biochemical characteristics of specific defense mechanisms, their genetics, interactions, and their quantitative and qualitative contribution to resistance. But their studies arc still inadequately known and relatively little have been contributed in terms of unique schemes of population management in achieving satisfactory pest control. It is apparent that there is no easy solution to resistance as a general phenomenon. For future challenging to effective control of insect pests which are resistant to the insecticides concerned, new insecticide groups with distinctly novel mode of action are urgently needed. It is clear, however, that a great understanding of the factors which govern the intensity of selection of field population for resistance could lead to far more permanently successive use of chemicals within the framework of integrated pest management than heretofore practiced.

• Economic and Environmental Geology
• /
• v.12 no.4
• /
• pp.181-195
• /
• 1979

The Nambu orebodies of the Okbang tungsten mine are hosted in the Precambrian amphibolite and Weonnam formation. These orebodies can be classified into two types; The scheelite-bearing ore vein occurring in the amphibolite (the Nambu 1, 2 adits) and tungsten-bearing quartz vein along the contact between the amphibolite and the Weonnam formation (the Young-ho, -1, -2, -3 levels). The scheelite-bearing ore vein in the amphilbolite is discontinuous, narrow, and highly irregular in geometry, occurring only within the amphibolite with which of the vein is graduational. Based on these feature of the mode of occurrence, the origin of this ore type might be attributed to a potential segregation of tungsten ore fluid in situ from hornblenditic basic magma of the host rock. Tungsten-bearing quartz vein, however, is considered to have deposited along the N30-60E trending fractures as a later hypothermal vein after the hornblendite was emplaced. The principal ore mineral is scheelite with minor amount of wolframite, and the gangue minerals are quartz, and small amounts of fluorite, pyrrhotite, chalcopyrite and calcite. Fluid inclusion study of minerals from the Nambu orebody reveals that the fluids in fluorite of the scheelite-bearning ore vein attained a temperature range of $208{\sim}256^{\circ}C$ and those in quartz from the tungsten-bearing quartz vein a temperature range of $220{\sim}357^{\circ}C$. The real formation temperatures can be somewhat higher than filling temperatures, if pressure correction is made. Chemical analysis of 8 amphibolitc samples on major and some trace elements indicate that the amphibolite is igneous origin. On a Niggli diagram (al-alk)versus c, the analytical values are plotted on an igneous field, and on a Niggli diagram mg versus c they follow a karroo igneous trend line. According to the Ba, Cr, and Ni versus Niggli mg plots suggested by Leake (1964), Okbang amphibolite fall outside a pelitic field and compare favorably with his plots form ortho-amphibolites. Analitical values of $MoO_3$ of 8 samples of scheelite minerals from the Nambu orebody indicate that the tungsten-bearing quartz vein (type n) of Nambu orebody shows a range from 1. 69% to 4.38% which is higher than 0.94%~3.25% $MoO_3$ for the scheelite-bearing ore vein (type I). This fact indicates that the type II was deposited in a lower $fO_2/higher$ $fO_2$ environment and under lower temperature than the type I. Analysis of major components $WO_3$, MnO, and FeO of 6 samples of wolframite from the type II veins revealed that they contain 73.35~76.2% $WO_3$, 7.94~11.63% MnO, and 10.53~14.82% FeO. MnO/FeO ratios of wolframite shows the range of 0.85~1.17 which suggests a slightly higher temperature type of deposits than other major tungsten deposits in the country.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.11 no.4
• /
• pp.201-215
• /
• 1999

Field measurements were made for long- and short-period waves and current velocities at the harbor mouth using pressure-type wave gauges and a current meter, respectively, at the Gamcheon Harbor which has a rectangular shape with a narrow entrance. The measured pressure data were subjected to spectral analyses after removing tidal effects by applying trend removal and high-pass filtering. For the band averaging of the raw spectra, in order to obtain good resolution over the entire frequency, instead of a constant band width, variable band widths were used, which gradually increase as marching from the lowest frequency towards higher frequencies. The Helmholtz resonance mode at the Gamcheon Harbor shows the relative amplification ratio of 9.2 at the wave period of 31.7 minutes, which is quite large compared with those at the harbors located on the east coast of Korea. The second and the third resonance period was 10.3 and 5.4 minute, respectively. On the other hand, the analysis of every 24 hours data shows that during storms the spectral densities are very large compared to those during calm seas and also the second and third resonances are predominant.

• Geophysics and Geophysical Exploration
• /
• v.9 no.1
• /
• pp.73-85
• /
• 2006

Array observations of the vertical component of microtremors are frequently conducted to estimate a subsurface layered-earth structure on the assumption that microtremors consist predominantly of the fundamental mode Rayleigh waves. As a useful tool in the data collection, processing and analysis, the spatial autocorrelation (SPAC) method is widely used, which in practice requires a circle array consisting of M circumferential stations and one centre station (called "M-station circle array", where M is the number of stations). The present paper considers the minimum number of stations required for a circle array for efficient data collection in terms of analytical efficacy and field effort. This study first rearranges the theoretical background of the SPAC algorithm, in which the SPAC coefficient for a circle array with M infinite is solely expressed as the Bessel function, $J_0(rk)$ (r is the radius and k the wavenumber). Secondly, the SPAC coefficient including error terms independent of the microtremor energy field for an M-station circle array is analytically derived within a constraint for the wave direction across the array, and is numerically evaluated in respect of these error terms. The main results of the evaluation are: 1) that the 3-station circle array when compared with other 4-, 5-, and 9-station arrays is the most efficient and favourable for observation of microtremors if the SPAC coefficients are used up to a frequency at which the coefficient takes the first minimum value, and 2) that the Nyquist wavenumber is the most influential factor that determines the upper limit of the frequency range up to which the valid SPAC coefficient can be estimated.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.13 no.3
• /
• pp.132-138
• /
• 2003

A stoichiometric mixture for $CdIn_2Te_4$ single crystal was prepared from horizontal electric furnace. The $CdIn_2Te_4$ single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The $CdIn_2Te_4$ single crystal was evaluated to be tetragonal by the power method. The (001) growth plane of oriented $CdIn_2Te_4$ single crystal was confirmed from back-reflection Laue patterns. The carrier density and mobility of $CdIn_2Te_4$ single crystal measured with Hall effect by van der Pauw method are $8.61\times 1016 \textrm {cm}^{-3}$ and 242 $\textrm{cm}^2$/V.s at 293 K, respectively. The temperature dependence of the energy band gap of the $CdIn_2Te_4$ single crystal obtained from the absorption spectra was well described by the Varshni's relation, $1.4750ev - (7.69\times10^{-3})\; ev/k)\;T^2$/(T + 2147k).The crystal field and the spin-orbit splitting energies for the valence band of the $CdIn_2Te_4$ single crystal have been estimated to be 0.2704 eV and 0.1465 eV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the $\Delta$so definitely exists in the $\Gamma_7$ states of the valence band of the $CdIn_2Te_4$ single crystal. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1-} B_{1-}$ and Cl-exciton peaks for n = 1.

• Journal of Preventive Medicine and Public Health
• /
• v.38 no.2
• /
• pp.141-146
• /
• 2005

Objectives: Particulate contaminants, such as total and respirable dusts, can harm the health of farm workers via several routes. The principal aims of this field study were to determine the concentrations and emissions of particulate contaminants: total and respirable dusts, in the different types of swine houses used in Korea, and allow objective comparison between Korea and the other countries in terms of swine housing types. Methods: The swine houses investigated in this research were selected with respect to three criteria: the manure removal system, ventilation mode and growth stage of pigs. Measurements of total and respirable dust concentrations and emissions in the swine houses were carried out on 5 housing types at 15 different farm sites per housing type. The swine houses investigated were randomly selected from farms situated within the central districts in Korea: province of Kyung-gi, Chung-buk and Chung-nam. Results: The total and respirable dust concentrations in the swine houses averaged $1.88\;and\;0.64mg/m^3$, ranging from $0.53\;to\;4.37mg/m^3$ and from $0.18\;to\;1.68mg/m^3$, respectively. The highest concentrations of total and respirable dusts were found in the swine houses with deep-litter bed systems: $2.94mg/m^3\;and\;1.14 mg/m^3$, while the lowest concentrations were found in the naturally ventilated buildings with slats: $0.83mg/m^3\;and\;0.24mg/m^3$, respectively (p<0.05). All the swine houses investigated did not exceed the threshold limit values (TLVs) for total ($10mg/m^3$) and respirable ($2.5mg/m^3$) dusts. The mean emissions of total and respirable dusts, per pig (75 kg in terms of live weight) and area ($m^2$), from the swine houses were 97.33 and 9.55 mg/h/pig and $37.14\;and\;12.83mg/h/m^2$, respectively. The swine houses with deep-litter bed systems showed the highest emissions of total and respirable dusts (p<0.05). However, the emissions of total and respirable dusts from the other swine houses were not significantly different (p>0.05). Conclusion: The concentrations and emissions of total and respirable dusts were relatively higher in the swine houses managed with deep-litter bed systems and ventilated naturally of the different swine housing types tested. In further research, more farms than the number used in this research should be investigated, which will present objective and accurate data on the concentrations and emissions of total and respirable dusts in Korean swine houses. In addition, personal sampling should be performed to objectively assess the exposure level of farm workers to particulate contaminants.

• Smart Structures and Systems
• /
• v.4 no.2
• /
• pp.221-232
• /
• 2008

This paper represents the final results of a research program sponsored by the European Commission through project WIND-CHIME ($\underline{W}$ide Range Non-$\underline{IN}$trusive $\underline{D}$evices toward $\underline{C}$onservation of $\underline{HI}$storical Monuments in the $\underline{ME}$diterranean Area), in which the possibility of using advanced seismic protection technologies to preserve historical monuments in the Mediterranean area is investigated. In the current research, the dynamic characteristics of two outstanding Mamluk-Style minarets, which similar minarets were reported to experience extensive damage during Dahshur 1992 earthquake, are investigated. The first minaret is the Qusun minaret (1337 A.D, 736 Hijri Date (H.D)) located in El-Suyuti cemetery on the southern side of the Salah El-Din citadel. The minaret is currently separated from the surrounding building and is directly resting on the ground (no vaults underneath). The total height of the minaret is 40.28 meters with a base rectangular shaft of about 5.42 ${\times}$ 5.20 m. The second minaret is the southern minaret of Al-Sultaniya (1340 A.D, 739 H.D). It is located about 30.0 meters from Qusun minaret, and it is now standing alone but it seems that it used to be attached to a huge unidentified structure. The style of the minaret and its size attribute it to the first half of the fourteenth century. The minaret total height is 36.69 meters and has a 4.48 ${\times}$ 4.48 m rectangular base. Field investigations were conducted to obtain: (a) geometrical description of the minarets, (b) material properties of the minarets' stones, and (c) soil conditions at the minarets' location. Ambient vibration tests were performed to determine the modal parameters of the minarets such as natural frequencies and mode shapes. A $1/16^{th}$ scale model of Qusun minaret was constructed at Cairo University Concrete Research Laboratory and tested under free vibration with and without SMA wire dampers. The contribution of SMA wire dampers to the structural damping coefficient was evaluated under different vertical loads and vibration amplitudes. Experimental results were used along with the field investigation data to develop a realistic 3-D finite element model that can be used for seismic risk evaluation of the minarets. Examining the updated finite element models under different seismic excitations indicated the vulnerability of such structures to earthquakes with medium to high a/v ratio. The use of SMA wire dampers was found feasible for reducing the seismic risk for this type of structures.

• Korean Journal of Crystallography
• /
• v.12 no.4
• /
• pp.197-206
• /
• 2001

A stoichiometric mixture of evaporating materials for AgInS₂ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films. AgInS₂ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy(HWE)system. The source and substrate temperatures were 680℃ and 410℃, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility of AgInS₂ single crystal thin film mea-sured from Hall effect by van der Pauw method are 9.35×10/sup 16/㎤ and 294㎠/V·s at 293K respectively. The temperature dependence of the energy band gap of the AgInS₂ obtained from the absorption spectra was well described by the Varshni's relation , E/sub g/(T)=2.1365eV-(9.89×10/sup-3/eV/K/)T²(T+2930K). The crystal field and the spin-orbit splitting energies for the valence band of the AgInS₂ have been estimated to be 0.1541eV and 0.0129 eV, respectively, by means of the photocur-rent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the Δso definitely exists in the Γ/sub 5/ states of the valence band of the AgInS₂ /GaAs epilayer. The three photo-current peaks ovserved at 10K are ascribed to the A₁-, B-₁and C₁-exction peaks for n=1.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.5B
• /
• pp.431-438
• /
• 2011

This study investigated the problem of mean-field bias correction under the assumption that the radar and rain gauge rainfall data follow the log-normal distribution. Regression curves for the average, median and mode of the radar and rain gauge rainfall were derived and evaluated for their usefulness. Additionally, these regression curves were compared with those derived under the assumption that the radar and rain gauge data follow the normal distribution. This study investigated the regression results for the Typhoon Meami occurred in 2003 as an example. As results, three regression lines with the radar rainfall as the independent variable were found to underestimate the rainfall, while those with the rain gauge rainfall as the independent variable to overestimate. Among three types of regression curves considered, the result for the average was most appropriate. However this case was found to be inferior to the regression line passing the origin under the assumption of the normal distribution with the rain gauge rainfall as its independent variable. So it was hard to conclude that the consideration of the log-normality on the correction of radar rainfall is beneficial.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.44 no.3
• /
• pp.64-69
• /
• 2007

Motion control of the system is a position control of motor. Motion control of an uncertain robot system is considered as one of the most important and fundamental research directions in the robotics. Some distinguished works using linear control, adaptive control, robust control strategies based on computed torque methodology have been reported. However, it is generally recognized within the control community that these strategies suffer from the following problems : the exact robot dynamics are needed and hard to implement, the adaptive control cannot guarantee the performance during the transient period for adaptation under the variation, the robust control algorithms such as the sliding mode control need information on the bounds of the possible uncertainty and disturbance. And it produces a large control input as well. In this dissertation, a motion control for the unmanned intelligent robot system using disturbance observer is studied. This system is affected with an impact vibration disturbance. This paper describes a stable motion control of the system with the consideration of external disturbance. To obtain the stable motion independently against the external disturbance, the disturbance rejection is strongly required. To address the above issue, this paper presents a Disturbance OBserver(DOB) control algorithm. The validity of the suggested DOB robust control scheme is confirmed by several computer simulation results. And the experiments with a motor system is performed to give the validity of applicability in the industrial field. This results make the easier implementation of the controller possible in the field.