• 생물환경조절학회지
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• 제14권3호
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• pp.174-181
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• 2005

Experiments were carried out to develop an optimal nutrient solution for the single-stemmed rose (Rosa hybrida L.) 'Red velvet' in a closed aeroponic system. Plants were grown in 1/3, 1/2, 1, or 3/2 strength of the nutrient solution of National Horticultural Research Station in Japan (NHRS). Significantly less changes of pH and EC ($dS{\cdot}m^{-1}$) in the drainage were observed in 1/2 strength treatment as compared to other treatments. The $NO_3-N$, K, Ca, and Mg concentrations in the drainage solution of 1/2 strength treatment were maintained at optimal levels. These results indicated that the rose uptakes of both nutrients and water was more stable than those in other concentration. The concentration of macronutrients in nutrient solution were adjusted based on the ratio of nutrient:water (n/w) taken up by plants grown in the 1/2 strength solution. The composition of the new solution (classified the University of Seoul (UOS) solution) was as follow; $NO_3-N$ 8.8, $NH_4-N$ 0.67, P 2.0, K 4.8, Ca 4.0, Mg 2.0 $me{\cdot}L^{-1}$. To further evaluate new solution on crop growth, the rose 'Red Velvet' was grown again in l/2, 1, and 2 strength UOS solution to compare with 1.0 strength PBG (proefstion voor bloemisterij en glasgroenpe) solution. Overall the plant growth, including the stem length and number of five-leaflet leaves was higher in 1.0 strength of UOS solution than other treatments. Results presented in this study indicate that the nutrients in the UOS solution are well balanced for the single-stemmed rose in the closed aeroponic system.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.145-146
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• 2019

In this study, we evaluated the early strength of red clay soil with the polymer aqueous solution at rammed earth construction. In order to satisfy the demolding strength of the formwork be due to the rammed of red clay soil, the polymer aqueous solution was added to evaluate the compressive strength at the early age according to the consolidation level. As a result, a high compressive strength was exhibited with the formulation to which the polymer aqueous solution was added.

• 한국자원식물학회지
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• 제16권3호
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• pp.223-229
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• 2003

본 연구는 양액재배 오이의 생장과 수량에 나쁜 영향을 주지 않는 적정 양액 농도를 구명하기 위해서 양액의 이온 농도를 달리하였다. Yamazaki의 오이 처방을 기본으로 하여 1/4, 1/2, 3/4, 1, 3/2, 2 배농도를 상이하게 처리하여 생장 특성, 수량 및 질소 함량을 비교하고자 수행하였고 그 결과를 요약하면 다음과 같다. 1. 생육 시기별 초장과 엽수의 증가속도는 저 농도 구인 1/2배 농도에서 가장 빠른 증가속도를 보였다. 2. 양액의 이온농도 차이에 따른 오이의 생육 형질은 유의적인 생장의 차이가 인정되지 않았으며, 생육 시기별 초장, 경장과 엽면적은 1/2배 농도구에서 수치상으로 가장 높은 값을 보였다. 3. 양액의 이온농도 차이에 따른 오이의 과실수량은 유의적인 차이가 인정되지 않았으며 주수에서는 고농도구인 2배 농도가 86.00, 86.75로 가장 높은 값을 보였고, 과실수는 1/4배 농도와 표준 농도에서 가장 낮은 74.25, 85.25를 보였으나 수량에서는 저 농도인 1/2배 농도와 3/4배 농도가 가장 높은 22.60, 22.07kg을 보였다. 4. 질소함량은 유의적인 차이가 인정되지 않았으며, l/2배 농도에서 대체적으로 높은 함량을 보였다. 5. 양액의 이온농도 차이에 따라 정식후 36일 조사 시기의 모든 생육형질과 수량 특성에서 수치상으로 높은 값을 보인 1/2배 농도에서의 상관관계는 초장과 경장은 고도로 유의한 정의 상관관계를, 초장과 엽면적에서는 유의한 정의 상관관계를 나타냈고, 주수와 과실수는 고도로 유의한 정의 상관관계를, 과실수와 수량은 유의한 정 의 상관을 나타냈다.

• 대한의용생체공학회:의공학회지
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• 제16권4호
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• pp.533-542
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• 1995

The present study investigated the effectiveness of pretreatment on dentin bonding. The adhesive resin was 5% 4-methacryloyloxyethyl trimellitate anhydride (4-META) in methyl methacrylate (MMA) combined with poly-MMA powder. Polymerization of this resin was initiated by tri-n-butyl borage (TBB). Ground bovine dentin samples were etched with either an aqueous solution of 10% citric (10-0 solution) (Group I) or aqueous solution of 10% citric acid and 3% ferric chloride(10-3 solution) (Group ll ). After etching, the primer (an aqueous solution of 35% hydroxyethyl methacrylate (HEM- A) and 5% glutaraldehyde was applied on the differently etched surfaces (Group III , Group IV). The 10-0 treatment showed the lowest tensile bond strength, followed by the 10-3 treatment, primer application after the 10-0 treatment and primer application after the 10-3 treatment. The relationship among the surface morphology after pretreatment, fractured surface morphology and tensile bond strength was examined. It revealed that the surface morphology change by different pretreatment influenced the bond strength and the resulting fractured surface morphology. The correlation of tensile bond strength with the fracture morphology was explained.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.689-696
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• 2003

In this study, ordinary portland cement, slag cement and micro cement which have been used in the construction fields were evaluated for the environmental effects and compression strength characteristics for curing solution. To find the leaching of C $r^{6+}$ characteristics in cement grouts, C $r^{6+}$ content tests were performed for the raw materials(cement powder). In addition, C $r^{6+}$ leaching tests were peformed for the homo-gel samples according to change of pH and each curing solution with the deionized water and leachate. Then, the unconfined compression strength tests were peformed with the homo-gel samples and the amount of changed C $r^{6+}$ was measured by curing solution.

• 생물환경조절학회지
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• 제16권3호
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• pp.199-204
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• 2007

배양액 농도가 호접란 미니다화성계 품종 P. amabilis와 P. Taisuco Red Jewel의 유묘와 중간묘의 생장에 미치는 영향을 알아보기 위해 ebb and low system을 이용하여 4개월 재배한 결과는 다음과 같다. 유묘의 경우 엽장과 엽폭이 P. amabilis는 배양액의 EC가 $0.5{\sim}1.0dS{\cdot}m^{-1}$일 때 가장 길었으나 P. Taisuco Red Jewel 배양액의 EC가 $1.5dS{\cdot}m^{-1}$일 때 가장 길었다. 반면에 근장과 근중은 두 품종 모두 배양액의 EC가 $0.5dS{\cdot}m^{-1}$로 낮을 때 가장 무거웠고 이러한 경향은 중간묘에서도 동일하게 나타났다. 잎의 생체중과 건물중은 P. amabilis의 경우 배양액의 EC가 $1.5dS{\cdot}m^{-1}$로 높을 때 가장 무거웠으며, 배양액의 EC가 낮아질수록 잎의 생체중과 건물중은 낮아졌다. 반대로 뿌리의 생체중은 배양액 EC가 $0.5dS{\cdot}m^{-1}$로 낮을 때 가장 무거웠고, 배양액의 EC가 높아질수록 가벼워졌으며, P. Taisuco Red Jewel에서도 같은 경향이었다. 중간묘의 경우 뿌리의 생체중과 건물중이 P. amabilis는 배양액 EC가 $0.5dS{\cdot}m^{-1}$로 낮을 때 가장 높았고, 배양액의 EC가 높아질수록 뿌리의 생체중은 낮아졌다. T/R율과 잎의 엽록소함량은 유묘와 마찬가지로 두 품종 모두 배양액의 EC가 $1.5dS{\cdot}m^{-1}$로 높을 때 가장 높았으며, 배양액의 농도가 낮아질수록 낮아졌다.

• 대한조선학회논문집
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• 제40권3호
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• pp.54-60
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• 2003

Fatigue strength of offshore structures or ship structures is significantly decreased due to corrosive environment condition such as sea water and/or coal, crude oil of cargoes, compared to that of on shore structures. In corrosive environment, fatigue strength of structures also depends on characteristics of weld material heat affected zone(HAZ). In this research work, rotary bending fatigue tests of parent material and HAZ of TMCP steel were performed in order to investigate the initiation and propagation of cracks both in air and in NaCl solution. Comparison of fatigue strength In relation with the salinity of NaCl were carried out as well. According to the test results weld material or HAZ of TMCP steel showed higher fatigue strength than that of the parent material. The fatigue strength of TMCP steel decreases drastically in NaCl solution compared to that of in air environment. In particular, more reduced fatigue strength is observed in 1% NaCl solution than in 3% NaCl solution.

• 대한치과보철학회지
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• 제34권3호
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• pp.593-610
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• 1996

The objective of this paper was to evaluate the shear bond strength of luting glass ionomer cement with defferent calcium based solution treatment on dentin surface. 120 extracted human teeth were classified into 12 group based on presence of smear layer on dentin surface and type of treatment solution. Smear layer remove on dentin surface was done using 6% citric acid for 60 seconds. Five different dentin surface treatment solutions(calcium acetate, calcium carbonate, clacium chlorided, calcium hydroxide, and calcium phosphate) were evaluated in this study. After surface modification, metal ring(inner diameter : 3mm, depth : 1mm) was placed to expose the same dentin surface area and inner space was filled with luting glass ionomer cement according to the recommended procedure for stadard clinical procedure. The shear bond strength of glass ionomer cement was determined after 24 hours. SEM was used for the evaluation of the surface morphologic changes and EDAX analysis was done for determination of the change of the calcium contents of treated dentin. Follwing conclusion can be drawn : 1. In the group of the dentin surface with smear layer, the calcium carbonate solution was the most effective for the increase of the clacium content and the shear bond strength of glass ionomer cement to dentin surfaces. 2. In the group of the calcium carbonate treated dentin with msear layer, the shear bond strength was increased twice compared to the control group and cohesive failure mode was observed. 3. The shear bond strength of cement was increased significantly be the removal of smear layer using 6% citric aicd. However, additional calcium solution treatments were not effective for further bond strength increase. 4. The shear bond strength of cement was significantly improved by both of the removal of smear layer and the calcium solution treatment, and the former was more effective for bond strength improvement. 5. The smear layer removed/calcium solution treated groups showed dentinal tubule obstruction and crystal attachment in SEM evaluation. However, the shear bond strengths of these groups were not increased compared to the smear layer removed/no dentin treatment group.

• Journal of Welding and Joining
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• 제14권2호
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• pp.36-45
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• 1996

Fatigue strength of the spot welded lap joint is considerably influenced by corrosive environments. Particularly, the chloride and the sulfide are most injurious to strength of the spot welded lap joint. Therefore, there is a need to evaluate its effect to corrosion fatigue strength for safe life design of spot welded structures. In order to evaluate their corrosion fatigue strength, corrosion fatigue tests on the spot welded lap joints of the uncoated and the coated high strength steel sheets were conducted in air and in 10% NaCl solution. Corrosion fatigue strength of the uncoated specimens were entirely lower than the coated one in NaCl solution, but those of the coated specimens in NaCl solution were lower than in air. And stress distribution in single spon welded lap joint subjected to tension-shear load was investigated by the finite element method. Using these results, we tried to evaluate corrosion fatgue strength of the various spot welded lap joints with maximum stress $\sigma_{max}$ at edge on loading side of the spot welded lap joint. We could find that corrosion fatigue strength could be quantitatively and systematically rearranged by $\sigma_{max}$.

• 한국농공학회지
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• 제15권4호
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• pp.3137-3146
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• 1973

This study was to investigate the effects of compaction, compressive strength and Atterberg limits in accordance with the temperatures changes. It was conducted on four soils-KJ, JJ, MH, SS-at temperatures of -1, 1, 3, 5, 7, 10, 15, 19, $22^{\circ}C$. These tests were obtained the maximum dry density and the optimum moisture content of four soils in accordance with temperature changes by using distilled water and $CaCl_2$ 10% solution, and were put to the compressive strength tests on remolded specimens of soils compacted at the optimum moisture content. The result of the study can be summarized as follows; The maximum dry density increased with an increase in temperature, and the use of $CaCl_2$ 10% solution had higher maximum dry density than distilled water. The optimum moisture content decreased with an increase in temperature, and the use of $CaCl_2$ 10% solution had lower optimum moisture content than distilled water. The maximum compressive strength was shown high peak from $7^{\circ}C\;to\;15^{\circ}C$, and the use of $CaCl_2$ 10% solution had higher maximum compressive strength than distilled water. The liquid limit and plasticity index decreased with an increased in temperature. It is estimated that the use of $CaCl_2$ 10% solution can lower the minimum compacted temperature from $2^{\circ}C\;to\;4^{\circ}C$ in low temperature.