• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1199-1208
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• 1994

In the country, supervision cost is being estimated by percentages of construction cost or cost plus a fixed fee without a reasonable standard. This type has no function for adjusting supervision cost according to variables, such as construction work complexity, extent of supervisory services, fluctuations in prices. In this study, an objective criterion to estimate supervision cost with improved supervisory services has been developed, in which adjusting functions as stated above should be properly considered. A comparative study of supervisory service systems in foreign countries and a survey through questionnaire were carried out for the study. An objective criterion from the results is proposed in the form of an expression or table.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1488-1492
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• 2007

현재 도시화로 인한 유출량의 증가 및 도달시간의 단축은 도시 재해의 한 원인이 되고 있으며 그에 따라 수공구조물에 대한 적정 설계가 필요하다. 하지만 계획단계에서부터 설계에 필요한 값을 예측하기는 매우 어려운 실정이다. 더구나 개발로 인해 매개변수가 변화함에 따라 유출 영향 분석이 어려울 뿐 아니라 이에 따른 연구가 미흡한 실정이기 때문에 모형매개변수의 민감도 분석을 통해 유출영향 분석 및 수공구조물 적정설계의 중요 기반자료로 활용하고자 본 연구를 수행하였다. 본 연구에서는 민감도 분석방법 중 절대 및 상대 민감도 분석 방법을 사용하여 각 유역의 지형학적 수문학적 매개변수들의 민감도 분석을 통해 상관관계를 확인하였다. 특히 대표적인 매개변수로서 유출계수 CN의 변화에 따른 유출량 및 유출 용적의 관계를 통해 CN의 증감에 따른 유출량 및 유출용적의 변화량을 산정하고, 또한 각 매개변수들간의 회귀분석을 통해 경험식을 작성, 제안하였다. 한편 현재 국내에서 사용중인 HEC-HMS를 모의하여 매개변수의 민감도 분석을 실시하였다. 본 연구의 결과로 CN값이 개발 전후 5% 증가시 유출량은 약 10%정도 증가한다는 것을 HEC-HMS모의와 자료의 분석을 통해 확인 할 수 있었다. 본 연구의 결과에 대해 검 보정 및 추가적인 자료수집을 통한 분석이 이루어지고, 매개변수 민감도 분석을 통한 국내 실정에 맞는 매개변수도출을 위한 연구가 계속적으로 수행된다면 미계측 유역에 대한 수공구조물의 적정설계에 상당부분 기여할 것으로 판단된다.

• Analytical Science and Technology
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• v.12 no.3
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• pp.177-183
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• 1999

The determination method of free acid in spent U-Al nuclear fuel solutions by Gran plot titration was described. Effect of U(VI) and Al(III) on the alkalimetric titration of nitric acid was investigated in oxalate complexing media as well as in noncomplexing media. Positive biases were observed in both titration media when the end-point was estimated by the Gran plot method. It was found that the cause of the bias was U(VI) in the oxalate complexing media, but Al(III) in the noncomplexing media. The relative error was less than 1% in the titration of 0.1 M $HNO_3$ at a U(VI) : Al(III) : $H^+$ mole ratio of up to 2:12:1 as long as the pH of the oxalate titration media was sustained to be below 5.0 at the beginning of titration. The method was successfully applied to the determination of nitric acid in a solution of HANARO reactor fuel with U:Al mole ratio of 1:6.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.125-130
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• 2010

It is necessary to re-establish the code and to control the quality of the recycled aggregate itself for ensuring the useability of the recycled aggregate using waste concrete. Generally, adhering mortar cause of the water absorption ratio increment and strength decreased at the surface of the aggregate of the recycled aggregate using waste concrete, thus removing the adhering mortar could increase the useability of the recycled aggregate in the concrete industry. In this study, as a quality control method of the recycled aggregate using waste concrete, the quality characteristic of the recycled aggregate according to the mixing proportion between the recycled and the natural aggregate is obtained Therefore, a system is established to reuse the recycled aggregate in the construction industry.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.1
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• pp.10-14
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• 1994

The slowly released potassium fertilizer was developed by mixing fly ash with KOH, anthracite coal powder, KCI, $K_2CO_3$ and $Mg(OH)_2$ as the substances for accelerating calcination. Measuring proper ratios of raw materials, we found that the anthracite coal powder was 12 percent and $Mg(OH)_2$ was two to three percent. The optimal calcination temperature and time were proved to be $850^{\circ}C$ and 30 minutes, respectively, however, the trial product with lower temperature and shorter time in calcination had low quality. The K solubility of the product was very low compared to that of the KCl fertilizer.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.05a
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• pp.591-594
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• 2020

불균형 데이터는 범주에 따른 데이터의 분포가 불균형한 데이터를 의미한다. 이런 데이터를 활용해 기존 분류 알고리즘으로 분류기를 학습하면 성능이 저하되는 문제가 발생한다. 오버 샘플링은 이를 해결하기 위한 기법 중 하나로 수가 적은 범주[이하 소수 범주]에 속한 데이터 수를 임의로 증가시킨다. 기존 연구들에서는 수가 많은 범주[이하 다수 범주]에 속한 데이터 수와 동일한 크기만큼 증가시키는 경우가 많다. 이는 증가시키는 샘플의 수를 결정할 때 범주 간 데이터 수 비율만 고려한 것이다. 그런데 데이터가 동일한 수준의 불균형 정도를 갖더라도 범주별 데이터 분포에 따라서 분류 복잡도가 다르며, 경우에 따라 데이터 분포에서 존재하는 불균형 정도를 완전히 해소하지 않아도 된다. 이에 본 논문은 분류 복잡도를 활용해 데이터 셋 별 적정 오버 샘플링 비율을 산출하는 알고리즘을 제안한다.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.2
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• pp.97-111
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• 2012

This study aims to find a proper construction cost calculation method by comparing unit prices of cost estimate in landscape construction among other public ordering construction projects. There were 7 out of 12 items from the actual work cost in the first half of 2011 were compared. The 12 items were classified as landscape Architectural construction and the 7 items were the approximate standard. As applied construction types, the comparable 35 items out of the 80 actual work cost items applied to 5 sites were compared to the unit price of the standard quantity per unit in March 2011, which was the approximate standard. Actual construction rate of the 7 items in the category of landscape sector was 104.86% for each item and 92.09% as a total construction cost. The high actual construction rate was caused by the high rate of seed spray depending on the status of applying rocks. However, there were more fundamental reasons for the cost generated from aslope treatment for grass and seed spray. So, it requires more detailed regulations on the modification factors for each soil type, the standard and needs to improve theillogical standard quantity per unit system. Actual construction rate of the 35 items in the applied sectors of civil engineering and architecture was 78.65% for each item and 71.31% (70.17%) as a total construction cost. This shows that actual unit cost cannot reflect actual cost structurally and standard quantity per unit system lacks practicality in terms of construction due to thelabor force. 85.1~91.2 % actual construction rate announced by the Ministry of Land and Maritime Affairs referred to the newly switched items. So the result was estimated as actual construction rate. This requires supplementation after verification in order to make the actual work cost produce at a proper rate. Also, standard quantity per unit system needs complementation with these actual data and so on.

• Journal of Mushroom
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• v.7 no.1
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• pp.22-26
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• 2009

These experiments were conducted to find the optimum mixing rate of used media for saving the production cost of Flammulina velutipes. The materials for media formation was used needle-leaf tree sawdust, media that finished 1th cultivation of F. velutipes, corncob meal, and rice bran, wheat bran as nutrition source. We inoculated the F. velutipes in 14 kinds of different media types and checked the spawn growth speed, fruit body quality and quantity. Two nutrition agents, which is rice bran and wheat bran, did not affected the incubation period, but the effective stem number, quality and quantity of fruit body was better at rice bran than wheat bran. The quality of fruit body produced at mixed 20% of used media (needle-leaf tree sawdust 60% + used media 20% + rice bran 20%) was similar to control plot (needle-leaf tree sawdust 80% + rice bran 20%), but the yield was improved 10% than control plot 130g. According as the used-media mixing amount increases, quality and quantity of fruit body became low remarkably. Therefore, the optimum mixing amount of used-media was 20% and it increased 10% of fruitbody yield.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.202-210
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• 2020

This study investigated the optimal levels of stand density control considering the stability of Larix kaempferi stands. A stand density management diagram was developed from 259 sample plots. Based on these data, we determined an optimal level of the stand density control by identifying the relationship between the relative yield index (Ry) and height-to-diameter ratio. The estimated r-square (R²) of the stand density management diagram is 0.600. The analysis of the relationship between Ry and the slender tree incidence showed that when the stand density exceeded a certain threshold and the ratio of slender trees rapidly increased. The critical value of Ry was 0.63. The results of this study are expected to contribute to the establishment of stand management strategies that can reduce damage from natural causes, such as wind and snow, and to develop stand practice systems for the improved productivity of commercial forests.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.1
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• pp.177-186
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• 1992

In this study, the proper mixing ratio of fly ash to bottom ash is evaluated and bearing capacity of this mixed ash is examined for use of highway embankment and subgrade materials in large quantities. Independently of the mixing ratio of fly ash to bottom ash or the method of compaction test, maximum dry density ${\gamma}_{dmax}$ and CBR value of anthracite mixed coal ash is greater than that of bituminous mixed coal ash. The mixed ashes to contain more fly ash than that of which the ratio of fly ash to bottom ash is 8 : 2, are slaked readily when the water contents of compaction are greater than optimum moisture content O.M.C. The proper mixing ratios of fly ash to bottom ash are about 5 : 5 to 6 : 4. Coal ashes mixed with these ratios exhibit proper physical and geotechnical properties for use of highway embankment and subgrade materials, and enable coal ashes to be used in large quantities.