• 한국농공학회논문집
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• 제62권1호
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• pp.95-104
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• 2020

The purpose of this study is to develop a pipe type soil sampler that can easily collect soil cross section servey and soil samples to conduct ecological environment surveys while minimizing ecological disturbance in the area subject to soil survey. Furthermore, this study develop the exponential type estimation specific weight formula (ESWF) that uses pipe type soil sampler to easily carry out soil cross section survey and soil sample while estimating the specific weight of the area using water content and soil sample length variation ratio (SLVRs) and to obtain apparent specific gravity, hardness, and max. porosity which are used as growth of corps and ecological environment index. The calibration results of ESWF showed a high degree of significance, with NSE for actual specific weight (γ₀) and calibration estimation specific weight (γ_ec) 0.95, R² for 0.954, and RMSE for 0.051. The verification results of ESWF showed a high significance, with NSE for actual specific weight (γ₀) and verification estimation specific weight (γ_ev) 0.881, R² for 0.978, and RMSE for 0.055.

• Nuclear Engineering and Technology
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• 제25권1호
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• pp.71-79
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• 1993

소둔시편 및 소둔 후 냉간가공한 하프늄시편에 대하여 양전자수명을 조사하였다. 소둔시편에서의 양전자수명은 187$\pm$3.7 psec인 반면, 소둔 후 냉간가공한 시편에서 격자결함에 포획된 양전자의 수명은 217$\pm$4.2 psec로 측정되었다. 양전자소멸측정 및 미세경도측정 방법을 이용하여 등시소둔에 의한 냉간가공시편의 회복 및 재결정 거동을 조사하였다. 재결정단계에서는 양전자소멸측정 과 미세경도측정값이 유사한 경향을 나타냈으나, 회복단계에서는 양전자소멸측정값이 매우 현저하게 변화하는 반면, 미세경도값은 거의 변화하지 않았다. 하프늄의 회복단계는 623 K부터 시작되며 재결정온도는 1023 K정도로 측정되었다.

• 원예과학기술지
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• 제35권4호
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• pp.510-522
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• 2017

To better understand the morphological variation for Perilla crop in different areas of China, we studied the morphological variation in 87 accessions (84 cultivated var. frutescens and three cultivated var. crispa) from high latitude (Northeast China) and middle latitude (North and Northwest China) areas of China by examining seven quantitative and 10 qualitative characters. Analysis of the morphological variation determined that there was significant morphological differences in five quantitative traits between cultivated var. frutescens and cultivated var. crispa, including effective number of branches (QN2), number of internodes (QN3), number of branches (QN4), length of the largest inflorescence (QN5), and days from germination to flowering (QN7). However, two quantitative traits-plant height and number of florets of the largest inflorescence-did not show any significant differences between cultivated var. frutescens and cultivated var. crispa. In addition, significant differences for six quantitative traits were found between the accessions of cultivated var. frutescens originating from high and middle latitude areas in China, which included QN2, QN3, QN5, number of florets of the largest inflorescence (QN6), and QN7. Principal components analysis (PCA) identified five quantitative characters [plant height (QN1), QN2, QN3, QN4, QN7] and six qualitative characters [fragrance of plant (QL1), color of reverse side of leaf (QL3), degree of pubescence (QL5), color of flower (QL6), shape of leaf (QL7), and hardness of seed (QL10)] that contributed to the positive direction on the first axis. The other quantitative and qualitative characters contributed to the negative direction on the first axis. Most accessions of cultivated var. frutescens and cultivated var. crispa were clearly separated by the first axis. In addition, most accessions of cultivated var. frutescens are from high latitude and middle latitude areas that were clearly separated by the first axis, except for several accessions. The findings from this study will provide useful information towards understanding the morphological variation of Perilla crop according to geographical distribution in high and middle latitude regions of China.

• 원예과학기술지
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• 제34권2호
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• pp.269-281
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• 2016

절화용으로 재배중인 주요 스프레이 국화 10품종의 형태적 특성과 관련된 요인을 조사하였으며 이들 평균치를 이용하여 변이계수, 유전율 및 유전자 전이율 등의 통계학적 분석을 통하여 얻은 결과를 요약하면 다음과 같다. 형태적 특성을 보면 줄기의 길이 46.4-54,9cm, 줄기의 최대 직경 5.6-8.5mm, 줄기의 경도 $0.17-0.70kg{\cdot}m^{-2}$, 줄기의 생체중 7.5-17.5g, 줄기의 건물중 1.6-3.3g, 줄기의 생체중:건물중의 비율 15.9-23.1%, 줄기 내 엽수 8.4-12.2매, 줄기 내 엽면적 $17.8-37.8m^2$, 줄기 내 잎의 생체중 5.3-18.6g, 줄기 내 잎의 건물중 0.5-1.4g 줄기 내 잎의 생체중:건물중의 비율 7.6-11.5%, 화서의 길이 10.1-18.6cm, 화서의 생체중 7.3-26.7g, 화서의 건물중 1.2-2.8g, 화서의 생체중:건물중의 비율 10.4-17.1%, 화심 직경 8.2-13.3mm, 꽃잎 폭 5.7-14.0mm, 꽃잎 길이 12.9-33.1mm, 꽃잎 두께 $157.8-354.4{\mu}m$였으며 각 특성별 품종 간 DMRT와 LSD를 검정한 결과 고도의 유의차가 인정되었다. 변이계수, 표현 변이계수, 유전 변이계수는 줄기의 길이 4.79-5.15%로서 가장 낮았으며 엽면적 62.97-65.21%로 가장 높았으나 환경 또는 오차 변이계수는 엽면적 1.71%로 가장 낮았고 잎의 건물중 19.30%로 가장 높았다. 유전율은 줄기의 생체중:건물중의 비율 68.69%로 가장 낮았고 줄기 내 엽면적 99.67%로 가장 높았다. 유전자 전이는 줄기의 경도 0.30으로 가장 낮았고 화서 내 잎의 두께 156.65로 가장 높았으며 유전자 전이율은 줄기의 길이 9.17%로 가장 낮았으며 엽면적 134.27%로 가장 높았다. 이와 같이 위에서 언급한 높은 값을 나타내는 형질들은 부가적으로 유전자 작용에 영향을 미치게 되며 경종의 개량을 위해 만족할만한 선발 계획을 수립할 수 있을 것이다.

• 한국표면공학회지
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• 제46권3호
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• pp.126-132
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• 2013

It was investigated that the effects of hydrogen charging on the properties of 590 MPa Dual Phase(DP) steels at the surface layers. The hydrogen-charging time was changed from 5 to 50 hours and current densities from 100, 150, and 200 $mA/cm^2$, respectively. It was found that the hydrogen content in the specimen was increased with as the charging time and the current density. The microvickers hardness of the subsurface zone was increased from 215.3 HV to 239.5 HV due to the increase in current density and charging time. The comparison of the absorbed energies tested by a small-punch (SP) test showed that the absorbed energy of the specimen was greatly reduced from 436 to 283 $kgf-mm^2$ because of hydrogen embrittlement. It was confirmed that bulb aspects of fracture surface became more brittle with increasing hydrogen content.

• Corrosion Science and Technology
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• 제13권4호
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• pp.130-138
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• 2014

Wall thinning can be classified into three types: flow-accelerated corrosion, cavitation erosion and solid particle erosion. This article presents a study of solid particle erosion, which frequently causes damages to power plants' pipe system. Unlike previous studies, this study uses a mechanism to make solid particles in a fluid flow collide with pipe materials in underwater condition. Experiment is conducted in three cases of velocity according to solid-water ratio using the three types of the materials of A106B, SS400, and A6061. The experiments were performed for 30 days, and the surface morphology and hardness of the materials were examined for every 7 days. Based on the velocity change of the solid particles in a fluid flow, the surface changes, the change in the amount of erosion, the erosion rate and the variation in the hardness of carbon steel and aluminum family pipe materials can all be determined. In addition, factor-based erosion rates are verified and a wall-thinning relation function is suggested for the pipe materials.

• 한국작물학회지
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• 제43권2호
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• pp.83-88
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• 1998

From the evaluation of physical properties such as springiness, gumminess, adhesiveness, chewiness and hardness by the texture analyzer, vegetable soybean lines with green seed-coat were best as compared with those with black, brown, mixed, and yellow seed-coats. A panel test evaluated on the basis of taste, sweetness, chewiness, and total scores also indicated that soybean lines with green seed-coat were the best. The total scores of panel test was decreased in the order of green > yellow> black> brown seed-coat colored soybean. The mean value of sucrose content obtained by HPLC analysis was highest in black seed-coat colored soybean, and followed by green, yellow, and brown soybeans. The highest sucrose content (8.22%) was observed in 180362, a soybean line with green seed-coat. The full-season type soybeans showed much higher sucrose content than summer types which are mainly cultivated on farmer's fields for vegetable purposes. The final 13 lines selected from 300 colored soybeans showed nearly the same panel scores as Miwongreen. However, these lines had a great deal of variation in sucrose content, and much higher readings in texture analysis than Miwongreen, especially in chewiness and hardness which were the most important properties in vegetable soybeans.

• Journal of Welding and Joining
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• 제4권2호
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• pp.21-29
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• 1986

The influence of welding heat input variation(600-900J/cm) and heat-treatment condition after welding on tensile strength of butt welded joint in $175Kg/mm^2$ strength level Maraging steel(Co-free and Co-containing) sheets was investigated on the basis of hardness distribution, microstructure of weld metal and fracture surface. The obtained main results are as follows; 1. The strength of weldment (UTS, NTS), joint efficiency showed a little decreasing tendency with the increase in welding heat input, and the elongation showed a little increasing tendency with the increase in the width of weld metal. It was considered because of the plastic constraint of the high strength base metal. 2. The strength of weldment was better in the solution treatment and aging than the aging only after welding due to the disappearance of almost denverite in weld metal. 3. The hardness distribution in weldment after welding and heat-treatment was almost similar to both Co containing and Co free Maraging steel with change in welding heat input. 4. The fracture was occurred at weld metal, and the fracture surface showed a relatively shallow dimples in both Co containing and Co free Maraging steel.

• 한국해양공학회지
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• 제25권6호
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• pp.72-79
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• 2011

In this paper, the fatigue characteristics of shot peened A7075-T651 alloy were compared with those of the specimens without the shot peening. The multi-spindle and single-spindle rotating bending fatigue testing machines were employed for the evaluation. Shot peening (SP) with various pressure (5 psi, 10 psi, 15 psi, 25 psi and 35 psi) were used in this test. In order to investigate the effect of the applied pressure during the SP, we carried out the surface roughness test, compressive residual stress test, hardness test, tensile test, VHCF (Very high cycle fatigue) test and SEM observation. SP induced the formation of remarkable compressive residual stress from the surface to certain depth of sample by means of the plastic deformation. The surface hardness and the fatigue characteristics of the specimens were also modified by the SP. According to the S-N curves, fatigue lives of shot peended sample with 25 psi measures 50 times higher than that of the untreated sample. The fatigue lives of shot peened sample with 15 psi and 35 psi measure approximately 10 times higher than that of the untreated ones.

• 한국정밀공학회지
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• 제29권4호
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• pp.395-408
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• 2012

An experimental investigation with 2.8kW Nd:YAG laser system was carried out to study the effects of different laser process parameters on the microstructure and hardness of STD11. The optical lens with the elliptical profile are designed to obtain a wide surface hardening area with uniform hardness. The Laser beam is allowed to scan on the surface of the work piece varying the power (1600, 1800 and 1900kW) and traverse speed (200, 400, 600, 800 and 1000mm/min) at three different F-numbers of lens. After laser surface treatment three zones, In the microstructure have been observed : melted zone(decarburization), heat affected zone(martensite), and the substrate.