• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.282-282
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• 2022

Arsenic (As) is a toxic heavy metal that affects the major rice-growing regions of the world and can cause cancer in humans. Rice paddy fields in South Asia are mostly dependent on arsenic-contaminated water sources due to which rice takes up the arsenic from the soil through roots and accumulates it in plant different parts. Here, we present a quantitative trait locus (QTL) mapping study to find out candidate genes conferring As toxicity tolerance in rice (Oryza sativa L.) at the seedling stage. Three weeks old, 120 double haploid CNDH lines derived from a cross between the Indica variety Cheongcheong and the Japonica variety Nagdong and their parental lines were used by treating with 25 μM As. After 2 weeks ofAs stress, 5 traits such as; shoot length (SL), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), and chlorophyll contents (CHC) were measured. A linkage map of 12 rice chromosomes was constructed from genotypic data DH lines using 778 SSR markers. The linkage map covered a total genetic distance of 2121.7 cM of the rice genome with an average interval of 10.6 cM between markers. A total of seventeen QTLs (LOD>2) were mapped on chromosomes 1, 2, 3, 6, 7, 8, 9, 11, and 12 using composite interval mapping with trait-increasing alleles coming from both parents. Five QTLs for SL, Two QTLs for RL, Five QTLs for SHL, Three QTLs for RFW, and Two QTLs for CHC were detected. The QTLs related to CHC were selected for forther study.

• 수산경영론집
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• 제15권1호
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• pp.58-80
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• 1984

The classification of islands is prerequisite for establishing a development policy to vitalize many-sided function of islands. We try to classify the 440 inhabited islands which exist in Jeon-Nam area and Kyong-Nam area by means of PCA. PCA begins with making correlation matrix of orignal variables. From this matrix we can comprehend the rough relationships between two variables. Next, we look for the eigenvalues which are roots of characteristic equation of correlation matrix. The number of eigenvalues is equal to that of original variables. We choose the largest eigenvalue λ$_1$among them and then look for the eigenvector of correlation matrix corresponding to the largest eigenvalue. Linear combination of eigenvector obtained above and original variables is namely first Principal Component (PC). Using an eigenvalue criterion(λ$\geq$ 1), we choose 3 PCs in Jeon-Nam area and 2 PCs in Kyong-Nam area. But we decide to consider only two PCs in both areas to faciliate a comparative analysis. Now, loss of information is 31.7% in Jeon-Nam area and 26.64% in Kyong-Nam area. PCs extracted by preceding procedure have characteristics as follows. The first PC relates to aggregate size of islands in case of both areas. The second PC relates to income per household, factors of agricultural production and factors of fisheries production in Jeon-Nam area, but in Kyong-Nam area it means distance from island and income per household. A classification of islands can be attained by plotting component scores of each island in graph used two PCs as axes and grouping similiar islands. 6 groups are formed in Jeon-Nam area and 5 groups in Kyong-Nam area. The result of this study in kyong-Nam area accords with prior result of study.

• Restorative Dentistry and Endodontics
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• 제16권2호
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• pp.143-154
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• 1991

The purpose of this study was to evaluate the sealing ability of five obturation methods in conjunction with sealer. Fifty extracted upper and lower anterior teeth were selected and the access cavities were prepared lingually with a round bur. The working length was determined with a #15K file, and the root canals were instrumented with a #40K file 1mm short of the apical foramen. The apical third of root canal was flared by step-back technique and the coronal two thirds of root canal using #2 - 3 Gates Glidden drills. And then, the teeth were randomly assigned to five groups of 10 teeth each. A thin coat of Tubliseal was placed into the canal into the canal using the # 35 reamer and the canals were filled by lateral condensation, vertical condensation, ultrasonic activated lateral condensation, ULTRAFIL injecting, and McSpadden compaction methods. All teeth were stored in 100 % relative humidity at 31c for 48 hours. The roots were suspended in 2 % methylene blue solution for 48 hours, left to dry for 24 hours and then, half side of root was removed longitudinally using the fissure bur. A Boley gauge wes used to measure the distance, to the nearest 0.1mm, from the apical foramen to the most coronal level of dye penetration. The measurement of dye penetration was statistically compared by Duncan's multiple range test The results were as follows 1. Ultrasonic group showed the best sealing ability among the all experimental groups, but there were statistically no significant difference in the sealing ability between ultrasonic group and vertical condensation group. 2. There were no statistically significant difference in the sealing ability among the lateral, vertical, and ultrasonic groups. 3. McSpadden group showed the worst sealing ability among the all exprimental groups.

• Journal of Microbiology and Biotechnology
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• 제22권4호
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• pp.437-447
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• 2012

Natural and beneficial associations between plants and bacteria have demonstrated potential commercial application for several agricultural crops. The sunflower has acquired increasing importance in Brazilian agribusiness owing to its agronomic characteristics such as the tolerance to edaphoclimatic variations, resistance to pests and diseases, and adaptation to the implements commonly used for maize and soybean, as well as the versatility of the products and by-products obtained from its cultivation. A study of the cultivable bacteria associated with two sunflower cultivars, using classical microbiological methods, successfully obtained isolates from different plant tissues (roots, stems, florets, and rhizosphere). Out of 57 plant-growth-promoting isolates obtained, 45 were identified at the genus level and phylogenetically positioned based on 16S rRNA gene sequencing: 42 Bacillus (B. subtilis, B. cereus, B. thuringiensis, B. pumilus, B. megaterium, and Bacillus sp.) and 3 Methylobacterium komagatae. Random amplified polymorphic DNA (RAPD) analysis showed a broad diversity among the Bacillus isolates, which clustered into 2 groups with 75% similarity and 13 subgroups with 85% similarity, suggesting that the genetic distance correlated with the source of isolation. The isolates were also analyzed for certain growth-promoting activities. Auxin synthesis was widely distributed among the isolates, with values ranging from 93.34 to 1653.37 ${\mu}M$ auxin per ${\mu}g$ of protein. The phosphate solubilization index ranged from 1.25 to 3.89, and siderophore index varied from 1.15 to 5.25. From a total of 57 isolates, 3 showed an ability to biologically fix atmospheric nitrogen, and 7 showed antagonism against the pathogen Sclerotinia sclerotiorum. The results of biochemical characterization allowed identification of potential candidates for the development of biofertilizers targeted to the sunflower crop.

• 한국산림과학회지
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• 제56권1호
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• pp.66-76
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• 1982

사방시공지(砂防施工地)에 널리 조림(造林)되는 리기다소나무의 근계분포(根系分布)와 토양(土壤)의 견밀도(堅密度)의 관계(関係)를 구명(究明)하고자 표본지(標本地)를 선정(選定) 대표목(代表木)의 경사하측(傾斜下側)에 환상(環状)의 토양단면(土壤斷面)을 만들어 각토층별(各土層別)로 토양경도(土壤硬度)를 산중식(山中式) Soil hardness tester로 측정(測定)하고 수근(樹根) (중세근(中細根))의 분포(分布)를 조사(調査)하여 분포(分布)한바 다음과 같이 요약(要約)할 수 있었다. 1) 토양(土壤)의 견밀도(堅密度)는 토심(土深)이 깊어짐에 따라 점차(漸次) 증가(增加)하여 평균(平均) 지표경도(指標硬度)는 I층(層)에서 14.6mm II층(層)에서 16.2mm, III층(層) 17.2mm, IV층(層)에서는 18.3mm, V층(層)에서는 19.8mm였다. 2) 수근(樹根) (중세근(中細根))은 표층(表層)에 이를수록 많이 분포(分布)하여 토층(土層)이 깊어짐에 따라 그 수(數)가 감소(減少)하여 I층(層) 수근(樹根)의 수(數)를 1(31%)로 할때 II층(層)은 0.84(26%), III층(層)은 0.6(18%), IV층(層)은 0.4(12%), V층(層)도 0.4(13%)이다. 3) 토양(土壤)의 견밀도(堅密度)와 수근(樹根)의 분포(分布)는 음(陰)의 상관관계(相関関係)에 있어 견밀도(堅密度)가 높아지면 이에따라 수근(樹根) 수(數)는 감소(減少)한다. 각(各) 토층별(土層別) 토양(土壤)의 견밀도(堅密度)와 수근분포(樹根分布)의 상관계수(相関係数)는 I층(層)은 -0.3875, II층(層)은 -0.5299, III층(層)은 -0.5573, IV층(層)은 -0.6922, V층(層)은 -0.7325, 전체평균(全体平均)은 -0.9469로서 모두 유의적(有意的)이었다. 4) 리기다소나무의 수근(樹根) (중세근(中細根))의 성장(成長)에 최적합(最適合)한 토양(土壤)의 견밀도(堅密度)는 지표경도(指標硬度)는 12.0~14.9mm로서 이 계급(階級)에 속(屬)하는 지표경도(指標硬度)는 33%이고 수근(樹根)의 분포(分布)는 41.8%이다. 또 지표경도(指標硬度) 20.9mm까지는 82%이나 수근(樹根) 93.2%가 분포(分布)하고 있어 지표경도(指標硬度) 20.9mm이하(以下)까지가 리기다소나무의 수근(樹根)의 생장(生長)에 적합(適合)하다고 사료(思料)된다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제32권5호
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• pp.464-473
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• 2006

Purpose: This study was performed to evaluate relationship between the inferior alveolar nerve injury and the findings of panoramic and tomographic images for preventing inferior alveolar nerve injury after the 3rd molar extraction. Material and Method: From April, 2005 to June, 2005, The 190 patients who visited in the Department of Oral and Maxillofacia Surgery, Chonnam National University Hospital and the panoramic radiographies were taken for extraction of the mandibular third molar, was selected. Among 215 mandibular third molars, Scanora tomographic imagings were taken in the 90 teeth which were overlaped to the mandibular canal in the panoramic imagies. In panoramic radiographies, the angulation, the level, the root morphology, and the superimposition sign of the mandibular third molars with the mandibular canal were evaluated. In the tomographic radiographies, the location and distance of the mandibular third molar from the canal were also evaluated. The relationships between these findings and the inferior alveolar nerve injury were examined. Results: In the panoramic findings, the inferior alveolar nerve injuries were occurred in the darkened roots (5 molars, 7%), the uncontinuous radiopaque image (3 molars, 7%), and the depositioned mandibular canal (2 molars, 10%). In the tomographic findings of 90 molars, 20 molars also had the superimposition imagies. Five molars in those molars (25%) had the inferior alveolar nerve injury after extraction. There were 10 patients who had the inferior alveolar nerve injury. The sensory was began to be recovered in 9 patients, except 1 patient, within 2 weeks, then fully recovered within 3 months. Conclusion: These results indicate that the depth mandibular third molar and the superimposition sign may be related with the risk of the inferior alveolar nerve injury after extraction.

• 구강회복응용과학지
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• 제22권2호
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• pp.173-180
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• 2006

Objectives The aim of this study is to compare the quality of root canal preparation completed using MFile-$System^{(R)}$ instrument ( Komet, Gebr.Brsaseler, Germany) and conventional stainless steel file in the canals of Maxillary molar teeth that had a canal curvature between $25^{\circ}$ or more Materials & Methods Buccal canals of 24 first and second maxillary molar teeth, extracted for periodontal and prosthetic reasons were used. Tissue fragments and calcified debris were removed from teeth by scaling and the teeth were stored in 10% formalin solution for 24 hour. Then, teeth were stored in saline until used. To be included the roots had to have completed formed apices and angle of curvature ranging between $25^{\circ}$ or more according to the criteria described by Schneider(1971). Palatal and Second mesiobuccal canals were not included. Teeth were embedded into transparent acrylic. The teeth were randomly divided into two experimental groups. All teeth were scanned by Dental CT (PSR9000N, Asahi, Japan) to determine the root canal shape before instrumentation. Image slices were prepared from the apical end point to the pulp chamber. The first two sections were 2 mm from the apical end of root and 2 mm below the orifice. Further section was recorded, dividing the distance between the sections of apical and coronal levels into two equal lengths. 12 teeth were instrumented using stainless steel fileand another 12 teeth were instrumented using MFile-$System^{(R)}$. Following the completion of the instrumentation, the teeth were again scanned and compared with the cross sectional images taken prior to canal preparation. Amount of transportation and centering ability was assessed. Student's t-test was used for statistical analysis. Result Less transportation occurred with MFile-$System^{(R)}$ rotary instrumentation than stainless steel instrument. MFile-$System^{(R)}$ had better centering ability than stainless steel instrument. Conclusion MFile-$System^{(R)}$ rotary instrumentation transported canals less and had good centering ability.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.252-252
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• 2017

Nowadays water shortage is becoming one of the biggest problems in the Korea. Many different methods are developed for conservation of water. Soil water management has become the most indispensable factor for augmenting the crop productivity especially on soybean (Glycine max L.) because of their high susceptibility to both water stress and water logging at various growth stages. The farmers have been using irrigation techniques through manual control which farmers irrigate lands at regular intervals. Automatic irrigation systems are convenient, especially for those who need to travel. If automatic irrigation systems are installed and programmed properly, they can even save you money and help in water conservation. Automatic irrigation systems can be programmed to provide automatic irrigation to the plants which helps in saving money and water and to discharge more precise amounts of water in a targeted area, which promotes water conservation. The objective of this study was to determine the possible effect of automatic irrigation systems based on soil moisture on soybean growth. This experiment was conducted on an upland field with sandy loam soils in Department of Southern Area Crop, NICS, RDA. The study had three different irrigation methods; sprinkle irrigation (SI), surface drip irrigation (SDI) and fountain irrigation (FI). SI was installed at spacing of $7{\times}7m$ and $1.8m^3/hr$ as square for per irrigation plot, a lateral pipe of SDI was laid down to 1.2 m row spacing with $2.3L\;h^{-1}$ discharge rate, the distance between laterals was 20 cm spacing between drippers and FI was laid down in 3m interval as square for per irrigation plot. Soybean (Daewon) cultivar was sown in the June $20^{th}$, 2016, planted in 2 rows of apart in 1.2 m wide rows and distance between hills was 20 cm. All agronomic practices were done as the recommended cultivation. This automatic irrigation system had valves to turn irrigation on/off easily by automated controller, solenoids and moisture sensor which were set the reference level as available soil moisture levels of 30% at 10cm depth. The efficiency of applied irrigation was obtained by dividing the total water stored in the effective root zone to the applied irrigation water. Results showed that seasonal applied irrigation water amounts were $60.4ton\;10a^{-1}$ (SI), $47.3ton\;10a^{-1}$ (SDI) and $92.6 ton\;10a^{-1}$ (FI), respectively. The most significant advantage of SDI system was that water was supplied near the root zone of plants drip by drip. This system saved a large quantity of water by 27.5% and 95.6% compared to SI, FI system. The average soybean yield was significantly affected by different irrigation methods. The soybean yield by different irrigation methods were $309.7kg\;10a^{-1}$ from SDI $282.2kg\;10a^{-1}$ from SI, $289.4kg\;10a^{-1}$ from FI, and $206.3kg\;10a^{-1}$ from control, respectively. SDI resulted in increase of soybean yield by 50.1%, 7.0% 9.8% compared to non-irrigation (control), FI and SI, respectively. Therefore, the automatic irrigation system supplied water only when the soil moisture in the soil went below the reference. Due to the direct transfer of water to the roots water conservation took place and also helped to maintain the moisture to soil ratio at the root zone constant. Thus the system is efficient and compatible to changing environment. The automatic irrigation system provides with several benefits and can operate with less manpower. In conclusion, improving automatic irrigation system can contribute greatly to reducing production costs of crops and making the industry more competitive and sustainable.

• 한국산림과학회지
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• 제87권3호
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• pp.466-474
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• 1998

본 연구는 폐광지 주변에서의 토양내 중금속(Cd, Cu, Zn, Pb) 오염 정도와 토양내 중금속 농도와 수목내 중금속 축적 농도와의 관계를 규명하여, 오염지역의 정화에 수목을 이용할 수 있는지를 확인하는 것을 목적으로 수행하였다. 경기도 화성군에 위치한 삼보광산과 광명시에 있는 가학광산에서 1997년 4월부터 9월에 걸쳐 토양 시료와 주변의 난티잎개암나무, 리기다소나무, 현사시나무, 진달래, 아까시나무를 채취하여 중금속 농도를 측정하였다. 두 광산지역의 광구에서 500m 이내 주변 토양은 중금속에 의한 오염 정도가 28~143ppm으로써 심각하지 않았으나, Zn(143ppm), Pb(97ppm)과 같은 중금속 농도는 독성을 나타낼 수 있는 수준이었다. 토양내 중금속의 농도는 Zn>Pb>Cu>Cd의 순이었으며, 광구의 중심에서 1.5km 이상 멀어질수록 증금속 농도는 10ppm 이내로 감소하였다. 각 수종별 중금속의 농도는 Pb를 제외하고, 현사시나무에서 가장 높았으며, 특히 잎에 고농도로 축적되어 있었고, Zn의 경우 91ppm이 검출되었다. 난티잎개암나무의 뿌리에서는 Cu와 Pb의 높은 농도로 검출되었다. 토양의 중금속과 수목 조직내 중금속 농도는 매우 높은 정의 상관을 보여주었으며, 리기다소나무에서 가장 높은 상관계수를 나타냈다. 토양에 대한 수목 조직의 중금속 농도비(Concentration Factors : CF)는 Zn이 가장 높은 값을 보였고 Pb이 가장 낮은 값을 보여주었다. 현사시나무는 CF값이 가장 높아서 중금속을 가장 많이 축적하고 있었다. 특히 토양의 중금속 농도에 대한 식물체의 농도비가 가장 높은 현사시나무는 중금속의 흡수 능력이 뛰어나 중금속 오염지에서 정화식물로 이용할 수 있으며, 리기다소나무는 토양의 오염 정도를 가장 잘 반영하는 수종으로 판단된다.