• Journal of Radiation Protection and Research
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• v.39 no.4
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• pp.199-205
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• 2014

In the field of neutron detections, $^3He$ gas, the so-called "the gold standard," is the most widely used material for neutron detections because of its high efficiency in neutron capturing. However, from variable causes since early 2009, $^3He$ is being depleted, which has maintained an upward pressure on its cost. For this reason, the demands for $^3He$ replacements are rising sharply. Research into neutron converting materials, which has not been used well due to a neutron detection efficiency lower than the efficiency of $^3He$, although it can be chosen for use in a neutron detector, has been highlighted again. $^{10}B$, which is one of the $^3He$ replacements, such as $BF_3$, $^6Li$, $^{10}B$, $Gd_2O_2S$, is being researched by various detector development groups owing to a number of advantages such as easy gamma-ray discrimination, non-toxicity, low cost, etc. One of the possible techniques for the detection is an indirect neutron detection method measuring secondary radiation generated by interactions between neutrons and $^{10}B$. Because of the mean free path of alpha particle from interactions that are very short in a solid material, the thickness of $^{10}B$ should be thin. Therefore, to increase the neutron detection efficiency, it is important to make a $^{10}B$ thin film. In this study, we fabricated a $^{10}B$ thin film that is about 60 um in thickness for neutron detection using well-known technology for the manufacturing of a thin electrode for use in lithium ion batteries. In addition, by performing simple physical tests on the conductivity, dispersion, adhesion, and flexibility, we confirmed that the physical characteristics of the fabricated $^{10}B$ thin film are good. Using the fabricated $^{10}B$ thin film, we made a proportional counter for neutron monitoring and measured the neutron pulse height spectrum at a neutron facility at KAERI. Furthermore, we calculated using the Monte Carlo simulation the change of neutron detection efficiency according to the number of thin film layers. In conclusion, we suggest a fabrication method of a $^{10}B$ thin film using the technology used in making a thin electrode of lithium ion batteries and made the $^{10}B$ thin film for neutron detection using suggested method.

• Geophysics and Geophysical Exploration
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• v.1 no.2
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• pp.101-109
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• 1998

Using airborne magnetic data, magnetic characteristics were studied at the Samryangjin caldera area developed in the volcanics of the Yuchon sub-basin, the south eastern part of the Gyeongsang basin. Residual magnetics, reduction to the pole, horizontal derivative, and vertical derivative maps are prepared. Using these maps, the magnetic lithofaces are zoned and the geological structures such as caldera and faults were qualitatively interpreted. In addition, the two quantitative interpretations were performed. Firstly, the forward modelling were done to the 14.5 line km crossing the caldera area to the northeast-southwest direction. Applying the 3-D Euler deconvolution method to the whole study area, the depth extent and the characteristics of the magnetic anomalous bodies were studied. According to the results, the magnetic lithofaces of the area are zoned by 4 units. In general, these are well matched with the geological distributions. But the biotite granites intruded in the northern boundary of the Samryangjin caldera show the high magnetic intensity, while the biotite granites of the other areas show the low magnetic intensity and the different magnetic lithofaces. Thus, we interpreted that the biotite granites are closely related with the volcanic activity of the Samryngjin caldera, and are intruded in the fracture zones developed along the caldera rim. The Samryangjin caldera and fault structures of the area can be easily recognized by the distinct magnetic structures from the various magnetic anomaly maps. Also the topographic characteristics well reflect these structures. The results of the forward modelling show that the magnetic basement depth of the Gyeongsang sedimentary basin is on the average about 6 km and in maximum 10 km. And the depth becomes shallower toward the caldera boundary due to the shallow intrusion of the volcanics. The results of the 3-D Euler method also show the caldera and fault structures. And the relatively shallow magnetic anomalous bodies which are related with the volcanics are generally developed to the east-west and northeast directions, while the deep magnetic anomalous bodies to the northwest direction.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.1
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• pp.1-15
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• 2016

Annual litterfall production and leaf area index (LAI, $m^2/m^2$) were estimated using litter traps in Gwangneung, Mt. Taewha and Mt. Gariwang. Annual total litter fall production including branch, bark, others was the highest in Gwangneung($7497.3{\pm}326.5kg/ha/yr$), which had the highest basal area at late successional stage, and followed by Mt. Taewha($5929.1{\pm}225.8kg/ha/yr$) and Mt. Gariwang($3,210.1{\pm}220.1kg/ha/yr$). Mt. Gariwang had the lowest litterfall production due to high elevation and short growing season even with the higher stand density and basal area than Mt. Taewha. Similarly, LAI, which was calculated by multiplying the mass of leaf litter with specific leaf area, was the highest in Gwangneung($5.99{\pm}0.69$) and followed by Mt. Taewha($5.20{\pm}0.24$) and Mt. Gariwang($4.06{\pm}0.42$) and the upper canopy species had the highest leaf area index in every sites (Gwangneung : 4.72, Mt. Taewha : 3.08, Mt. Gariwang : 2.19). However, species specific LAI estimation based on the relationship between basal area and leaf area was limited due to upper canopy species non-proportionality of basal area with LAI. In addition, the comparison between direct and indirect LAI measurement showed the importance of canopy clumping, especially at high density. Our study emphasized the necessity of direct LAI measurement using litter fall traps especially at temperate deciduous forest with diverse species.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.9-18
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• 2017

Arsenic (As) has been considered as the most toxic one among various hazardous materials and As contamination can be caused naturally and anthropogenically. Major forms of arsenic in groundwater are arsenite [(As(III)] and/or arsenate [(As(V)], depending on redox condition: arsenite and arsenate are predominant in reduced and oxidized environments, respectively. Because arsenite is much more toxic and mobile than arsenate, there have been a number of studies on the reduction of its toxicity through oxidation of As(III) to As(V). This study was initiated to develop photocatalytic oxidation process for treatment of groundwater contaminated with arsenite. The performance of two types of light sources (UV lamp and UV LED) was compared and the feasibility of goethite as a photocatalyst was evaluated. The highest removal efficiency of the process was achieved at a goethite dose of 0.05 g/L. Based on the comparison of oxidation efficiencies of arsenite between two light sources, the apparent performance of UV LED was inferior to that of UV lamp. However, when the results were appraised on the basis of their emitting UV irradiation, the higher performance was achieved by UV LED than by UV lamp. This study demonstrates that environmentally friendly process of goethite-catalytic photo-oxidation without any addition of foreign catalyst is feasible for the reduction of arsenite in groundwater containing naturally-occurring goethite. In addition, this study confirms that UV LED can be used in the photo-oxidation of arsenite as an alternative light source of UV lamp to remedy the drawbacks of UV lamp, such as long stabilization time, high electrical power consumption, short lifespan, and high heat output requiring large cooling facilities.

• Journal of Korean Society of Forest Science
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• v.80 no.1
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• pp.42-53
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• 1991

1. The forest vegetation of the Mt. Baek-Hwa situated in the northwestern Kyungsangpookdo of Korea, on $36^{\circ}16^{\prime}00^{{\prime}{\prime}}{\sim}36^{\circ}19^{\prime}20^{{\prime}{\prime}}N$ and 127 53'20"~127 56'30"E was studied by the method of Zurich-Montpellier School. In the present time, the original vegetation have almost been dominated by substitutional communities such as secondary forests of Pinus, Quercus, Zelkova, Acer or Fraxinus and Pinus rzgida plantations. Some secondary forests developing along the ravine and in northwestern part of slope are, however, maintained in natural condition, and contain some species of the original climax vegetation. They are classified as follows : I. Quercus mongolica-Fraxinus siebol diana community(Mountain forests), I-A. Acer pseudo-sieboldianum -Carex okamotoi group, I-B. Pinus densiflora group, I-B-a. Typical subgroup, I-B-b. Rhododendron schlippenbachii subgroup, II. Fraxinus rhynclzophylla-Acer mono community(Valley Forests), II-A. Acer pseudo-sieboldianum group, II-B. Zelkova serrata group, II-B-a. Typical subgroup, II-B-b. Lindera erythrocarpa subgroup, II-C. Querczrs serrata-Platycarya strobilacea group, II-C-a. Typical subgroup, II-C-b. Lindera erythrocarpa subgroup. 2. Judging from the coincidence method, the structure and distribution of the forest communities was more related to topography than altitude. 3. Considering the actual vegetation, relict species, occurrence of natural seedlings and saplings, climate, successional trends of trees and topographic or edaphic climax conditions, it seems that potential natural vegetation of the area mainly composed of Quercus mongolica, Carpinus laxiflora, Zelkova serrata, Fraxinus rhynchophylla. 4. The flora of the vascular plants collected from this area consists of 108 families, 371 genera, 613 species, 2 subspecies, 88 varieties, 6 forms and 709 taxa in total.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.2
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• pp.39-44
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• 2020

Recently, numerous researches are being conducted in flexible substrate to apply to wearable devices. Particularly, Conductive substrate researches that can implement the wearable devices on clothing are massive. In this study, we formed fiber substrate spraying CNT and Pd mixed solution on it and plated metal layer with electroless plating. Used SEM equipment and EDS analysis to analysis structure of the plated fiber substrate and discovered Ni layer was created. For check electrical properties, mapping was performed to check surface resistance and distribution of resistance of electroless plated fiber substrate with 4-point probe. It was confirmed that conductivity was improved as the duration of electroless plating was increased, and it was found that distribution of resistance by surface location was uniform. Changes in resistance due to mechanical stress were measured through tensile, bending, and twisting tests. As a result, it was confirmed that resistance change of flexible substrate gradually disappeared as plating time increased. Using UTM (Universal testing machine), it was analyzed mechanical properties of the electroless plated substrate with respect to changes in plating time were improved. In the case of conductive fiber substrate in which electroless plating was performed for 2 hours, tensile strength was increased by 16 MPa than fiber substrate. Based on these results, we found that Ni-CNT-Fabric flexible substrate is adequate for clothing-intergrated conductive substrate and we positively expect that this experiment shows flexible substrate can adapt to and develop not only a wearable device technology but also other fields needing flexibility such as battery, catalyst and solar cell.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.239-244
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• 2007

In order to investigate the effect of fluorine ion in the $Li_{1-x}FeO_2Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8) cathode material, it was synthesized $Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8, $0.05{\le}y{\le}0.15$) cathode materials at $350^{\circ}C$ for 10hrs using solid-state method. $Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8, $0.0{\le}y{\le}0.1$ was composed many large needle-like particles of about $1-1.5\;{\mu}m$ and small particles of about 50-100 nm, which were distributed among the larger particles. However, $Li_{1-x}FeO_{1.85}F_{0.15}-Li_xMnO_2$ material showed slightly different particle morphology. The particles of $Li_{1-x}FeO_{1.85}F_{0.15}-Li_xMnO_2$ were suddenly increased and started to be a spherical type of particle shape. $Li/Li_{1-x}FeO_{1.9}F_{0.1}-Li_xMnO_2$ cell showed a high initial discharge capacity of 163 mAh/g and a high cycle retention rate of 95% after 50 cycles. The initial discharge capacity of $Li/Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ ($0.05{\le}y{\le}0.15$) cells increased according to the increase of F content. However, the cycleability of this cell was very rapidly decreased when the substituted fluorine content is over 0.1. We suggested that too large amount of F ion fail to substitute into the $Li_{1-x}FeO_2-Li_xMnO_2$ structure, which resulted in the severe decline of battery performance.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.283-287
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• 2007

KIER has been developing the anode-supported flat tubular solid oxide fuel cell unit bundle for the intermediate temperature($700{\sim}800^{\circ}C$) operation. Anode-supported flat tubular cells have Ni/YSZ cermet anode support, 8 moi.% $Y_2O_3$ stabilized $ZrO_2(YSZ)$ thin electrolyte, and cathode multi-layer composed of Sr-doped $LaSrMnO_3(LSM)$, LSM-YSZ composite, and $LaSrCoFeO_3(LSCF)$. The prepared anode-supported flat tubular cell was joined with ferritic stainless steel cap by induction brazing process. Current collection for the cathode was achieved by winding Ag wire and $La_{0.6}Sr_{0.4}CoO_3(LSCo)$ paste, while current collection for the anode was achieved by using Ni wire and felt. For making stack, the prepared anode-supported flat tubular cells with effective electrode area of $90\;cm^2$ connected in series with 12 unit bundles, in which unit bundle consists of two cells connected in parallel. The performance of unit bundle in 3% humidified $H_2$ and air at $800^{\circ}C$ shows maximum power density of $0.39\;W/cm^2$ (@ 0.7V). Through these experiments, we obtained basic technology of the anode-supported flat tubular cell and established the proprietary concept of the anode-supported flat tubular cell unit bundle.

• Korean journal of applied entomology
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• v.59 no.3
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• pp.233-241
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• 2020

Several hard tick species in Ixodidae are medically important pests that transmit infectious disease including severe fever with thrombocytopenia syndrome (SFTS). In Korea, the number of SFTS patients continues to steadily increase since its first report in 2013, and Gyeongsangbuk-do (province) is the second most frequent area of SFTS patient occurrence. In order to investigate the distribution of ticks in Sangju city, we collected ticks using the flagging method from 26 sites comprising urban green area, vulnerable area of management, and rural area, and examined SFTS virus from the collected ticks in 2019. Based on Collection Index (CI = tick number / 1 h / 2 people), CI 143 ticks, including Haemaphysalis longicornis, Haemaphysalis flava, and Ixodes nipponensis, were collected; the most abundant species among the three tick species was H. longicornis (CI 138, 96.5%). Ninety two percent (CI 131) of ticks were collected in vulnerable area of management, where people cannot easily enter and are not managed by city hall, whereas only 8.4% (CI 12) were collected in the urban green area and rural area. Regarding SFTS virus detection, virus was not investigated from 26 pools containing CI 143 ticks. The results of this study are expected to be used as a recommendation for ensuring the safety of local residents from tick-borne diseases.

• Korean journal of applied entomology
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• v.59 no.3
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• pp.243-250
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• 2020

Two meridic diets, N4 and N6, containing pinto bean, wheat germ, soybean, whole milk and sucrose as main nutrients were developed for rearing Spodoptera frugiperda (Noctuidae) larvae. Six larval instars were observed when neonate larvae were individually raised on these diets in small petri-dishes (ø 50 × 10 mm, 19.6 ㎤) at 25℃ and 15:9 h (light:dark) photoperiod. The average pupation rate of 97.8% on the N4 diet was significantly higher than the rate of 85.6% on N6 diet. The emergence rates were 92.0% on N4 diet and 93.5% on N6 diet, with a non-significant difference. The larval periods were 17.9 and 17.7 days for females, and 18.7 and 18.5 days for males, for N4 and N6 diets, respectively, with non-significant differences between diets and sexes. The pupal periods on both diets were identical (11.1 days for females and 12.8 days for males), despite differences between sexes. The pupal weights of both sexes on N4 diet were identical with a value of 257 mg, whereas those on N6 diet were 256 and 263 mg for females and males, respectively, with a non-significant difference. The longevity of female adults that emerged on N6 diet was 13.8 days and longer than 8.6 days on N4 diet. The pre-oviposition periods were 5.0 and 4.2 days on the N4 and N6 diets, respectively, with a non-significant difference, however, the oviposition period of 6.5 days on N6 diet was longer than the period of 3.9 days on N4 diet. The effective fecundity on N6 diet was 1,392 eggs (maximum 1,776) and was higher than that of 942 eggs (maximum 1,694) on N4 diet, with a non-significant difference. The egg hatching rates on N4 and N6 diets were 79.2 and 79.8%, and egg periods were 3.0 and 2.9 days, respectively, with non-significant differences.