• The Journal of Engineering Geology
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• v.34 no.1
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• pp.137-146
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• 2024

The pertinent Korean Industrial Standard (KS F) requires that rocks dried at 105 ± 5℃ be taken out of the oven into air and weighed on a scale. However, when rocks are exposed to air after the drying process, they absorb moisture, meaning that their weight will increase. In this study, eight cubic samples of Hwangdeung granite of different sizes were used to measure and compare the dry weight. The dry singularity weight measured in air was smaller than that measured in the drying oven. The difference in dry weight showed a positive correlation with sample size. Conversely, the difference in dry weight per unit weight of rock showed a negative correlation with sample size. The weight of a rock sample exposed to air is determined by the magnitude of the influence of convection currents occurring around the heated rock and the influence of moisture absorption in air. A singularity occurs when the magnitudes of these two effects are equal. The larger the rock sample, the longer the time taken for the singularity to occur, the greater the weight loss of the sample, and the longer the time taken for the sample to return to the initially measured weight on account of the greater moisture absorption for larger samples than smaller samples. In the future, research into the singularity and dry weights measured inside the drying oven will help to identify and address the limitations of the current KS F testing regulations.

• Journal of the Korean GEO-environmental Society
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• v.24 no.3
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• pp.5-14
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• 2023

The dry unit weight of the soil can be obtained by measuring the weight of the oven dried soil. According to the Korean Industrial Standards (KS F), oven dried soil at 110±5℃ continuously increases in weight when exposed to air. However, there is no regulation on the weight measurement time of oven dried soil, making it difficult to accurately measure the dry weight. In this study, a method to easily determine the dry weight was presented through the analysis of the weight singularity that appears during weight measurement. The weight singularity represents the smallest value among the measured weights, and is the weight at which the effect of moisture absorption in the air of the sample is minimized. In the course of the experiment, a container was selected using a statistical analysis method, and a photograph of the soil samples were presented using an optical microscope. In addition, the temperature of the weight singularity was measured using a non-contact infrared thermometer. As a result of analyzing the weight singularity of six types of soil, including Jumunjin sand, Naeseong stream sand, Yecheon weathered granite soil, Jeju sand, Sabkha sand, and Ulleung sand, the weight singularity of oven dried sample appeared between 8 and 27 seconds after weight measurement, and the temperature ranged from 103.4 to 108.13℃. The weight decrease rate of the singularity was 0.0066 to 0.0085% depending on the soil samples.

• Journal of the Korean GEO-environmental Society
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• v.24 no.9
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• pp.25-32
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• 2023

The Korean Industrial Standards (KS F) have a various regulations for measuring the weight of dried soil and rock. However, if the dried weight is measured in air after drying at 110±5℃ or 105±5℃, a weight singularity occurs, in which the weight decreases and then increases as the measurement time continues. In this study, basaltic rock from Ulleung Island was oven dried at 40 to 110℃. The weight was measured on an electronic scale with a sensitivity of 0.0001g (0.1mg) to find weight singularities. A method to easily determine the dry weight using the weight singularities was presented. As a result of analyses of the singularity of rock specimen according to temperature, the singularities were appeared in the temperature range of 40 to 110℃, and the weight of the singularity was smaller as the heating temperature increased. In particular, the weight singularity duration appeared, and the duration of the singularity was shorter as the heating temperature increased. The results of the convection measurement experiment showed that the cause of the singularity is the convection phenomenon caused by the contact of the heated rock with the air. The weight decrease of oven dried rock occurs when the effect of convection is dominant over the effect of air moisture absorption. Conversely, the weight increase of rock occurs when the effect of air moisture absorption is dominant over the effect of convection.

• The Journal of Engineering Geology
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• v.32 no.3
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• pp.401-410
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• 2022

This work reports an oven drying test performed on weathered granite soil from Yecheon, Korea, in order to find an effective method for measuring the weight of pure soil particles. After samples were oven dried, weights measured following desiccation using the method specified by the Korean Industrial Standard (KS F) were compared with weights measured without prior desiccation. Soil samples exposed to air for 45 min after oven drying absorbed moisture from the air and gradually increased in weight. When a desiccator was used, results measured 30 s after exposure to air indicated weight increases of 0.103-0.735% (depending on the particle size of the soil) relative to equivalent samples measured without desiccation. Using a desiccator after oven drying leads to overestimation of the pure soil weight. Therefore, measuring the weight of a soil sample immediately after oven drying without using a desiccator can reduce the error of weight measurement.

• Journal of the Korean Society of Food Science and Nutrition
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• v.18 no.1
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• pp.29-33
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• 1989

As one of the application of microcomputer for data acquisition and temperature control of food drying process, these studies designed and built 'the interface system, measuring sensors of weight and temperature, temperature control system'. The basic and assembly language was used to operating these system. These system measured successfully the variables such as weight and temperature during food drying, and controlled Automatically the drying temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.6
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• pp.335-343
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• 2002

Methods of bedsoil analysis were difficult to be applied universally because use and material of bedsoil are diverse from country to country. Korean Standard Methods for Bedsoil Analysis was developed to measure the water content, water retention, and saturated hydraulic conductivity. Fifty-three samples for horticultural bedsoil and nine samples for paddy rice bedsoil in the current market were collected. Water content of bedsoil was determined using gravimetric method through $105^{\circ}C$ oven-dry for 16 hours, but different calculations between horticultural and paddy rice bedsoils were chosen according to different predominant component, plant residue or mineral. Water content percentage of horticultural bedsoil was calculated as [(weight of sample before oven-dry - weight of sample after oven-dry)/(weight of sample before oven-dry)]${\times}100$, while that of paddy rice bedsoil as [(weight of sample before oven-dry - weight of sample after oven-dry)/(weight of sample after oven-dry)]${\times}100$. Water retention was measured at water potential -0.5, -1, -3, -5, -7, -10 kPa by Sandbox method and saturated hydraulic conductivity was measured by constant head method using acryl cylinder (${\Phi}5cm{\times}L\;20cm$). By new 'Korean Standard Methods of Bedsoil Analysis', the average water content of horticultural bedsoil was obtained 46.34%(w/w) and that of paddy rice bedsoil 16.89%. For horticultural bedsoil, easily available water(EAW), water buffering capacity(WBC), and optimal matric potential(OMP) was estimated at 28.4%, 7.01%, and -5.60 kPa, respectively. Optimal moisture content was 44.41% and average saturated hydraulic conductivity for bedsoils was estimated at $28.4cm\;min^{-1}$.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2002.11a
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• pp.131-186
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• 2002

우리나라 유통상토에 대한 물리적 표준분석법을 설정하기 위한 연구를 실시하였다. 국내 시중에 유통되고 있는 53개 품목의 원예용 상토와 9개 품목의 수도용 상토를 대상으로 설정된 분석법을 적용하여 실험하였다. 입자밀도의 측정은 가스형 피크노메타(Micromeritics Co. Model 1305)를 사용하면 속도와 정확성 면에서 매우 유리하였다. 용적밀도는 구미에서 Sandbox법에 의한 용적밀도를 기본으로 하기 때문에 이와 유사한 성적을 얻을 수 있는 다양한 실험을 한 결과, 추다짐법(Plunger compaction method)이 가장 유의성 있는 측정 방법으로 밝혀졌다. 한편 가스형 피크노메타법에 의한 우리나라 유통상토의 입자밀도는 원예용이 1.93, 수도용이 2.43 Mg m$^{-3}$로 나타났으며, 추다짐법에 의한 용적밀도는 원예용이 0.22, 수도용이 1.01 Mg m$^{-3}$로 각각 나타났다. 수분함량은 105$^{\circ}C$ 건조기에서 16시간 건조하여 수도용상토는 (최초 무게-건조 후 무게) / (건조 후 무게) $\times$ 100으로, 원예용상토는 (최초무게 - 건조 후 무게) / (최초 무게) $\times$ 100으로 하였다. 보수력은 주로 저압용으로서 Eijkelkamp사의 Sandbox법을 사용하여 0.5, 1, 3, 5, 7, 10 ㎪의 수분장력 상태의 수분함량을 조사하였다. 포화수리전도도는 직경 5cm$\times$높이 20cm인 아크릴 원통을 이용하여 정수위별에 의한 포화수리전도도를 측정하였다. 신분석법에 의한 유통상토의 수분함량은 원예용이 평균 46.34%, 수도용이 평균 16.89%이었고 원예용 상토의 EAW는 28.4%, WBC 7.01%, OMP는 5.60 ㎪로 나타났으며, 육묘를 위한 적정 수분함량은 44.41%이었고 포화수리전도도는 1.71 cm $min^{-1}$이었다. 상토 평량시 무게를 비교한 결과 상토 부피를 달리하여도 고도의 유의성이 있었고, 상토 20cc의 평균무게는 4.92g(2.08-8.83g)이었다. 상토의 EC 측정시 상토:물의 비율이 1:2(v:v)와 1:5(v:v)분석치에 2.5배한 EC 값과는 고도의 정의 상관관계가 있었으며, 유럽법과 일본법(전농)과의 관계는 고도의 정의 상관관계가 있었다 또한 새로운 분석법(v:v 1:5)으로 측정한 EC의 평균값은 국내산 0.64, 수입산 0.33 dS m$^{-1}$이 었다. 상토의 pH 측정시 상토:물의 비율을 1:2(v:v)와 1:5(v:v)와의 관계에서는 정의 상관관계를 보였으며, 유럽법과 일본법(전농)과의 관계도 역시 고도의 정의 상관관계가 있었고, 신 분석법에(v:v 1:5) 의한 분포비율은 국내산, 수입산모두 pH 6.1-6.5의 범위에서 가장 높았다.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.477-484
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• 2010

The majority of currently domestic dried sea foods is holding sanitary safety on storage and distribution, a structural problem to be in quality serious to sun drying. This paper the productive times and the on-site operation that production is fixed are easy, and it have reported the experimental results that carried out on development of a drying system toward field which can keep the highest quality and economy.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.59-63
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• 2008

Purpose: The purpose of this study is to understand a relation of water content measurement with two different method, water removal method and dry method. Methods: 72 hydrogel contact lens containing various water content (ranged from 47% to 58%) were measured by the gravimetric method at 20$^{\circ}C$and 21% of the humidity. We weighed the dried test specimen at room temperature for 30 min after cooling. Results: In dry blotting method, the water content was measured to 47.43${\pm}$8.48%. The water contents was measured to 48.15${\pm}$8.36% with wet blotting condition. It was found that wet blotting method showed the higher water content of about 7% than dry blotting method. In water content with two dry methods, each of results was measured by 47.89${\pm}$8.06% and 49.56${\pm}$7.06%. In case of microwave method, the water content was measured significantly higher water content of about 1.67% than vacuum oven method. However, no statistical difference was found (p>0.05). Conclusions: In water removal method (Dry blotting method and Wet blotting method) to weigh hydrated test specimen, wet blotting method showed significantly higher water content than dry blotting method. Also in case of dry methods (vacuum oven and microwave) to weigh dry test specimen, water content of microwave method showed higher water content than vacuum oven method, but it should be noted that microwave oven method must be used carefully to measure accurateness on the specimen position and wave power.

• Journal of the Korean earth science society
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• v.38 no.2
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• pp.150-160
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• 2017

In order to determine the porosity of rock, the 'standard test method for porosity and density of rock' proposed by the Korean Society for Rock Mechanics is commonly used. However, the standard test method, which uses a drying oven, takes 8 to 24 hours to complete the test in taking samples out of the oven every four hours and measuring the weight of the specimen. To complement these disadvantages, we devised a method for measuring rock porosity by using a microwave oven. The devised method reduced the cause of errors and the inconvenience occurred in the process of weighing samples by constructing a weight monitoring system, which monitors the drying process. A suitable heating/pause time was set up to maintain the temperature of sample below $105{\pm}3^{\circ}C$ in drying process, and an alarm system was implemented in order to stop drying process when the weight change of the rock sample is within 0.1% of the initial weight. The porosity was determined from the dry weight of the sample, which was obtained by the curve fitting of weight monitoring data. Then, the porosities obtained by using the microwave oven were compared with those obtained by the standard test method. Test results using sandstone samples showed that the porosities obtained by a microwave oven was similar to those obtained by the standard method and the porosity difference between two methods was as large as 0.4%. In addition, repeated porosity measurement using the same specimen showed that the standard deviation of the porosity, which reflects the precision of the measurement was as good as 0.23%. Therefore, a microwave oven porosity measurement system can give the porosity of rock samples with high reliability.