• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.1
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• pp.38-46
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• 2016

In this study, the bleeding tests were performed to investigate the effects of cement paste(w/c=0.42) on bleeding through varying the number of strand and the diameter of cylinder. The test variables were specified by differing the diameter of cylinder and the number of strand. The bleeding test was performed with respect to all diameter parameters by with or without strand. In addition, the number of strands were specified at four levels, 0, 1, 2, and 3 EA in case of 50 mm cylinder. In case of without strand, the bleeding rate was determined at low level under 2%. Moreover, all of the specimens had similar value in the measurement error. In case of with strand, maximum bleeding rate was 10%. As the diameter of cylinder decreased, the bleeding rate was decreased. The bleeding rate was altered rapidly in between 50 to 100mm of diameter. Even though bleeding rate was increased according to the increase in the number of strand, these tendency for bleeding rate was negligible with the measurement error.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.241-241
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• 2016

반도체 선폭이 20 nm급까지 감소함에 따라 기존에 수율에 문제를 끼치던 공정 외부 유입 입자뿐만 아니라, 공정 도중에 발생하는 수~수십 나노의 작은 입자도 수율에 악영향을 끼치게 되었다. 이에 따라 저압, 극청정 조건에서 진행되는 공정 중 발생하는 입자를 실시간으로 모니터링 할 수 있는 장비에 대한 수요가 발생하고 있다. Particle beam mass spectrometer (PBMS)는 이러한 요구사항을 만족할 수 있는 장비로 100 mtorr의 공정 조건에서 5 nm 이상의 입자의 직경별 수농도를 측정할 수 있는 장비이다. PBMS로 입자의 수농도를 측정하기 위해서는 PBMS 전단에서 입자를 중앙으로 집속할 필요가 있다. 공기역학렌즈는 PBMS 전단에서 입자를 집속시키기 위해 일반적으로 널리 사용되고 있는 장비로 여러 개의 오리피스로 이루어져 있다. 공기역학렌즈를 지나는 수송 유체와 입자는 이러한 연속 오리피스를 거치면서 팽창과 수축을 반복하며, 관성력의 차이로 인해 입자가 중앙으로 집속된다. 그러나 기존 공기역학렌즈는 고정된 직경의 오리피스를 사용하기 때문에 설계된 공정조건 이외에는 입자의 집속효율이 감소한다는 단점을 지닌다. 따라서 공정조건이 바뀔 경우 공기역학렌즈를 교체해야 되며, 진공이라는 환경하에서 이러한 교체는 많은 시간과 노력을 요구로 한다. 본 연구에서는 이러한 공기역학렌즈의 문제점을 해결하기 위해 다양한 공정조건에서 교체 없이 사용할 수 있는 새로운 형태의 직경 가변형 공기역학렌즈인 조리개형 공기역학렌즈를 제안하였다. 기존 연구를 통해 조리개형 공기 역학 렌즈가 다양한 압력 범위 내에서 나노입자를 성공적으로 집속할 수 있음을 보였지만, 장비를 상용화하기 위해서는 사용자가 좀 더 쉽게 렌즈직경을 결정 할 수 있어야 한다. 이에 본 연구에서는 조리개형 렌즈의 중공 직경에 따른 입자 집속 특성을 평가하였으며, 최종적으로 압력과 집속하고자 하는 직경에 따라 렌즈 중공 직경을 결정할 수 있게 해주는 데이터 베이스를 제작하였다.

• The Korean Journal of Mycology
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• v.30 no.1
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• pp.18-22
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• 2002

This study was carried to investigate efficient pot diameter and substrate weight in pot cultivation of Pleurotus ostreatus. Cultivating substrate was pine sawdust+beet pulp+cotten seed flour (50 : 30 : 20, v/v). Ranges of pot diameter and substrate weight were $10{\sim}20\;cm\;and\;600{\sim}2,500\;g/pot$, respectively. Smaller pot diameter resulted in longer pot length according to increasing substrate weight, so mycelial growth period and total cultivation period was retarded. Wider pot diameter resulted in a little lower biological efficiency in the same substrate weight. Heavier substrate weight was brought higher yield but lower biological efficiency. Average yield according to pot diameter was decreased at wider than 14 cm during second flush. And average biological efficiency according to substrate weight was lower than 100% at heavier than 1,200 g/pot during second flush. So suitable pot diameter and substrate weight in pot cultivation of Pleurotus ostreatus were estimated $10{\sim}14\;cm\;and\;800{\sim}1,200\;g$, respectively.

• Journal of Korean Society of Forest Science
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• v.77 no.2
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• pp.216-222
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• 1988

This study was conducted to investigate the effect of meteorological factors on the diameter growth and Key-year in Pinus koraiensis and Pinus densiflora trees grown in Chuncheon and Hongcheon. The results obtained were summarized as follows : 1. The diameter growth of Pinus koraiensis was better than that of Pinus densiflora grown in the same meteorological condition and site environment. 2. The influence of meteorological factors on the diameter growth of Pinus koraiensis was the highest in the descending order fog, hours of sunshine, precipitation, relative humidity, warm index, and evaporation. 3. The influence of meteorological factors on the diameter growth of Pinus densiflora was the highest in the descending order fog, hours of sunshine, relative humidity, precipitation, and warm index. But evaporation was not significant. 4. The Key-years for Pinus koraiensis and Pinus densiflora trees appeared in 1964 and 1913 when the diameter growth was influenced by the specific climate change.

• Journal of Convergence for Information Technology
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• v.10 no.7
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• pp.147-152
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• 2020

The research is carried out to analyze the cost-effectiveness of blasting patterns with regard to the diameters and design of blasting holes. Blasting patterns for single diameter array, and mixed diameter array were comparatively analyzed with regard to drilling and charging time, and materials required. The number of blasting holes required for single array pattern and mixed array pattern were 138 and 93 holes, respectively. From the drilling time analysis, reduction in time and its efficiency of mixed pattern were 139 minutes and 25%, respectively, in comparison with single pattern. Charging time reduction and its efficiency of mixed blasting pattern were evaluated as 22.5 minutes per worker and 33%, respectively, compare to single blasting pattern. The explosive quantities of G1 and G2 required for single array patterns were 270 and 30, while those were 222 and 20 for mixed array patterns for tunnelling 4m. And single pattern required 45 more detonators than the mixed pattern. The evaluation of material required can also be positive parameter for cost reduction of tunnel construction.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.621-628
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• 2003

Stud shear connectors are the most commonly used shear connectors: up to 22mm studs are usually used in steel-concrete composite structures. To expand the current design codes for stud connectors, large studs with a diameter of more than 25mm should be investigated. Through push-out tests on large stud shear connectors that transcend the limitation of current design codes, fatigue behavior was investigated and comparisons with design equations performed. The shear stiffness of the connectors in elastic range was evaluated through shear tests on 25mm, 27mm, and 30mm studs and compared with those from static tests. The fatigue behavior of large studs was discussed in terms of residual slip and load-slip curves. The initiation of fatigue cracks in the welding part could be detected through the history of displacement range. Test results showed that the design fatigue endurance of S-N curves in current design codes could be applied to large stud shear connector.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.429-435
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• 2020

In this study, physical properties and EMP shielding performance evaluation of cement paste according to the amount of milled carbon fiber was conducted to develop EMP shielding cement using carbon fiber. The length of the milled carbon fiber used was 100㎛, and it was used as a cement admixture because it showed a powdery form to the naked eye. As a result of the experiment, when 5% of the amount of cement was used, the milled carbon fiber was effective in compressive strength and EMP shielding, and the shielding effect did not increase when used beyond that. As a result of examining the EMP shielding performance according to the thickness of the specimen, the plain without milled carbon fiber had no effect of increasing the shielding rate according to the thickness. The shielding performance of the specimens using the milled carbon fiber increased as the thickness increased. Therefore, in order to increase the EMP shielding rate when comparing and evaluating the performance according to the amount of milled carbon fiber used and the thickness of the specimen, 5% of the milled carbon fiber used is optimal. In addition, the method of increasing the thickness is considered to be effective.

• Journal of agriculture & life science
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• v.53 no.6
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• pp.23-33
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• 2019

In accordance with a change in the management information system containing the management record and planning for the entire national forest in South Korea by an amendment of the relevant law (The national forest management planning and methods, Korea Forest Service), in this study, average, the maximum, and the minimum values for DBH were presented while only average values were required before the amendment. In this regard, there is a need for an estimation algorithm by which all the existing values for DBH established before the revision can be converted to the highest and the lowest ones. The purpose of this study is to develop an estimation equation to automatically show the minimum and the maximum values for DBH for 12 main tree species from the data in the national forest management information system. In order to develop the estimation equation for the minimum and the maximum values for DBH, there was exploited the 6,858 fixed sample plots of the fifth and the sixth national forest inventory between in 2006 and 2015. Two estimation models were applied for DBH-tree age and DHB-tree height using such growth variables as DBH, tree age, and height, to draw the estimation equation for the maximum and the minimum values for DBH. The findings showed that the most suitable model to estimate the minimum and the maximum values for DBH was Dmin=a+bD+cH, Dmax=a+bD+cH with the variables of DBH and height. Based on these optimal models, the estimation equation was devised for the minimum and the maximum values for DBH for the 12 main tree species.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.567-574
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• 2022

Coronary artery disease (CAD) and atrial fibrillation (AF) are known to share many risk factors. In particular, in the case of acute coronary syndrome, it may be difficult to clearly determine the diameter of the vessel due to complete occlusion of the vessel and thrombus. Thus, the relationship between the diameter of the coronary arteries was evaluated to be used as a reference data before the treatment of coronary arteries and drug selection in patients with AF. From January 2020 to August 2022, images of coronary angiography (CAG) with AF and normal sinus rhythm (NSR) on electrocardiography were target. In both subjects, images of normal coronary artery without lesions as a result of CAG were used. For all vessels, the diameters of the vessels were measured by dividing them into proximal, middle, and distal parts, and the measured diameters were divided by the average for evaluation. As a result of analyzing the left anterior descending artery diameter, the vessel diameter of the AF patient was 2.24±0.26 mm, which was smaller than that of the NSR patient, 2.86±0.38 mm, and was statistically significant. (p<0.001) As a result of analyzing the left circumflex artery diameter, the vessel diameter of the AF patient was 2.34±0.28 mm, which was smaller than the vessel diameter of the NSR patient, 2.87±0.29 mm, and was statistically significant. (p<0.001) As a result of analyzing the diameter of the right coronary artery, the vessel diameter of the AF patient was 2.68±0.5 mm, which was smaller than the vessel diameter of the NSR patient, 3.35±0.4 mm, and was statistically significant. (p<0.001) Considering that the coronary artery size of AF patients is significantly smaller than the coronary vessel size of NSR patients, it is considered as a useful study to be used as a reference for evaluating coronary artery diameter when the arrhythmia is AF. In particular, it is considered to be a study that can be helpful in diagnosing lesions, using drugs before and after surgery, and choosing to use auxiliary devices such as intravascular ultrasound.

• Journal of Power System Engineering
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• v.8 no.4
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• pp.5-10
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• 2004

본 연구는 단기통 4행정 기관의 배기단의 형상에 따른 실험과 수치해석이 소개되었다. 흡 배기 밸브가 작동하고 있고, 주요한 배기단의 변수로는 배기단 직경이 적용이 되었다. 실험결과로는 배기단의 직경에 따라 배기 압력은 많은 영향을 받았는 것으로 나타났다. 배기단의 직경이 감소하였을때, 배기압력파의 진폭과 파수가 증가되었다. 배기단의 직경이 증가 하였을 때, 배기압력파의 진폭이 감소하였다. 직경이 22mm 일 때의 소음의 주파수 분석이 16mm와 28mm 보다 진폭이 작게 나타났다.