• 한국농촌건축학회논문집
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• 제21권1호
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• pp.37-44
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• 2019

Recently, various tourist products using hanok have increased rapidly. In the meantime, there is a steady demand for Hanok architecture. However, there are many negative perceptions about wood deformation and biodeterioration. Wood deformation and biodeterioration are related to moisture content. And the cracks occur in the process of removing water from the wood. Therefore, this study investigates the moisture content and cracks of dried hanok made of wood according to the drying method of wood. Drying methods include natural seasoning and artificial seasoning. There was a difference in moisture removal depending on drying period and method of natural seasoning. Drying time should be about 3 years for natural seasoning, so the moisture content of the wood is stable. In addition, the moisture absorption rate was low even in a humid environment where the voids were removed. However, natural seasoning is time consuming. Artificial seasoning, on the other hand, can quickly remove moisture from the wood and reduce porosity, but it is costly. Cracks that occur during the drying of wood may become problematic in appearance and stability due to wider spacing over time. As a result, the difference in the moisture content of the timber depending on the drying method and drying period of the wood was maintained even after the formation. These gaps appeared to be differences in moisture absorption in a wet environment.

• Journal of Biosystems Engineering
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• 제13권3호
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• pp.52-58
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• 1988

This study was conducted to develop a grain moisture content measurement sensor for automatic control of rough rice drying by natural air. For the above objective, the electrod type sensor was designed and tested. The sensor was able to produce electrical resistance which changes with moisture content of grain. An A/D converter and a micro-computer wed for processing measurement data of sensor. The developed sensor satisfied most design requirements and the results of statistical analysis show that there it no difference between the measurement method of sensor developed and of the dry-oven. Using the developed sensor and measurement system, we are able to measure moisture content of rough rice automatically in drying by natural air.

• 한국농공학회지
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• 제16권3호
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• pp.3539-3542
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• 1974

Maximum density and optimum moisture content of a soil may be one of the very important properties to be specified in the design of earth structures and their works. However, the determination of these soil properties may not be done without the necessary equipment and time-consuming field tests. This study was conducted to develop an easier method by determing the relations between the natural moisture content and optimum moisture content and between maximum density and optimum moisture content so determined. These velations are remarkably defferent according to the areas where the samples were taken, and thus analysis of the experimental results are shown by regions as follows: Eastern Districs:{{{{Tdmax= { 1} over {0.0090Wopt+0.417 } ( delta = +- 0.042, gamma =0.92) Wopt=0.251WN+8.5( delta = +- 2.41%, gamma =0.87) }}}} Southern Districts: {{{{Tdmax= { 1} over {0.0088Wopt+0.412 } (delta = +- 0.083, gamma =0.89) Wopt=0.332WN+8.42(delta = +- 3.41%, gamma =0.84)}}}}Central Districtsl1): {{{{Tdmax= { 1} over {0.0112Wopt+0.383} ( delta = +- 0.052, gamma =0.97) Wopt=0.758WN+2.606( delta = +- 4.72%, gamma =0.79)}}}}($\delta$:Standard Deviation, ${\gamma}$:Correlation Coefficient)

• Journal of Ecology and Environment
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• 제33권1호
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• pp.47-57
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• 2010

To understand day-to-day fluctuations in soil moisture content in Seoul, I simulated daily soil moisture content from 1908 to 2009 using long-term climatic precipitation and temperature data collected at the Surface Synoptic Meteorological Station in Seoul for the last 98 years with a hydrological simulation model, BROOK. The output data set from the BROOK model allowed me to examine day-to-day fluctuations and the severity and duration of droughts in the Seoul area. Although the soil moisture content is highly dependent on the occurrence of precipitation, the pattern of changes in daily soil moisture content was clearly quite different from that of precipitation. Generally, there were several phases in the dynamics of daily soil moisture content. The period from mid-May to late June can be categorized as the initial period of decreasing soil moisture content. With the initiation of the monsoon season in late June, soil moisture content sharply increases until mid-July. From the termination of the rainy season in mid-July, daily soil moisture content decreases again. Highly stochastic events of typhoons from late June to October bring large amount of rain to the Korean peninsula, culminating in late August, and increase the soil moisture content again from late August to early September. From early September until early October, another sharp decrease in soil moisture content was observed. The period from early October to mid-May of the next year can be categorized as a recharging period when soil moisture content shows an increasing trend. It is interesting to note that no statistically significant increase in mean annual soil moisture content in Seoul, Korea was observed over the last 98 years. By simulating daily soil moisture content, I was also able to reconstruct drought phenomena to understand the severity and duration of droughts in Seoul area. During the period from 1908 to 2009, droughts in the years 1913, 1979, 1939, and 2006 were categorized as 'severe' and those in 1988 and 1982 were categorized as 'extreme'. This information provides ecologists with further potential to interpret natural phenomenon, including tree growth and the decline of tree species in Korea.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.405-412
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• 2000

A natural air in-bin grain dryer with a grain circulator was developed for on farm use. Natural air drying test for rough rice was carried out to evaluate drying rate, uniformity of moisture content distribution in grain bed and energy consumption. It took 10 days to dry 8 ton of paddy rice from 21.9%(w.b) to 16.7%(w.b) moisture contents using the prototype dryer. The average drying rate was 0.52%/day. The uniformity of moisture content after drying was superior to the conventional natural air dryer where is grains were not circulated during drying periods. The dryer performance evaluation index was 738.3KJ/(kg.water), which was more effective than that of grain circulation t)pe hot air dryer(3,500-5,000 KJ/kg.water).

• Journal of Biosystems Engineering
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• 제6권1호
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• pp.83-92
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• 1981

A simulation model of natural air drying to predict the changes of the grain moisture content and dry matter loss of rough rice was developed by the application of mass diffusion theory. A series of simulated drying tests was conducted using the 10 year weather data (1970-1979) obtained from Cheongju, Chuncheon, Daegu, Daejeon, Jeonju, Jinju and Suweon in Korea. System performance factors treated in this study were initial moisture content, airflow rate, bin diameter and grain depth. The results obtained in this study are summarized as follows: 1) The simulation model used in this study was validated with actual experimental results and was applicable to the natural air drying of rough rice. 2) Minimum airflow rates for safe drying were determined for different initial moisture contents and regional weather conditions as shown in Table 6. 3) Equations for estimating drying time and dry matter loss in terms of airflow rate and initial moisture content were derived in the form of an exponential function. 4) These results show that the natural air drying system of rough rice is feasible in Korea even for the poorest drying condition.

• Journal of Biosystems Engineering
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• 제16권1호
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• pp.49-59
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• 1991

A numerical model was developed to predict grain temperature, moisture content, and drymatter loss of rough rice in a grain storage bin. This model simulated conduction, natural convection, and mass transfer occuring inside a storage bin. The results obtained from the study were as follows. 1. The predicticted results agreed well with the measured results. 2. Rough rice could be store safely for one year in Suweon, Dajeon, and Jingu area. 3. Aeration of 5-day was required to control grain temperature and moisture content rise early in Jun and July, respectively.

• 한국지하수토양환경학회지:지하수토양환경
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• 제10권3호
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• pp.46-51
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• 2005

본 연구에서는 토양에 유출된 염소계 휘발성 유기물질의 자연저감에 대한 흡착과 미생물분해의 영향을 알아보았다. 대표적인 염소계 휘발성 유기물질인 TCA (1,1,1-trichloroethane), TCE (trichloroethylene) 및 PCE (tetrachloro ethylene)의 자연저감율을 비교하기 위해 세가지 조건에서 바이얼 실험을 수행하였다; (1) 멸균, (2) 비멸균 그리고 (3) 비멸균/탄소원첨가. 또한 각각의 조건에서 수분함량에 의한 영향을 알아보기 위해 세 가지로 적용하였다; (1) wilting point (12%, w/w), (2) field capacity (29%, w/w), (3) saturation (48%, w/w). 100일 경과 후, TCA 및 TCE는 field capacity에서 미생물에 의한 자연저감이 상대적으로 활발히 일어났다. 비멸균/탄소원 첨가 토양은 멸균한 토양에 비해 유기물질의 제거율에서 현격한 차이를 나타내었다. PCE는 미생물 및 탄소원 첨가에 의한 영향을 보이지 않았다.

• 한국농공학회지
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• 제30권2호
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• pp.55-66
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• 1988

This study was conducted to investigate the various engineering properties and correlationshops among the soil constants of alluvial clayey deposits distributed in the bay of Asan and their results are summarized as follows : 1. Grain size distribution of soil was consisted of 12 % of clay, 46-73 % of silt, 2-23 % of sand, and as for the consistency characteristics, 26-36 % of liquid limit, 18-21 % of plastic limit and 6-16 % of plastic index, and so the soil belonging to as a lower plastic nonorganic clay, it's specific gravity was 2,66-2.70, and the location on the plastic chart was approximately above the A-line. Z The natural moisture content and unit weight were 30-43 % and 1.76-1.87 g I cm$_3$, respectively, and according to increment of natural moisture content, the unit weight was decreased, and the initial void ratio and degree of saturation were shown of 0,87-1119 and 92- 100 %, most of saturated. 3. Cone resistance value which was shown 2.4 - 6.5 kg / $cm^2$ was a little lower and it was increased with the depth of layer and shown the formular $q_c=0.7_z+1.32$. 4. Unconfined compression strength was about 0.18-0.43kg /$cm^2$, cu, 0.1-0.22kg / $\psi$, $2-6^{\circ}$ under uu-test condition of triaxial, and CCU, 0.08-0.3 kg/cm , $\psi$, $12-18^{\circ}$ under the condition of cu-test. 5. Pre-consolidation load of characteristics of consolidation was 0.4-0.8 kg / $cm^2$, compression index, about 0.17-0.33. 6. Liquid limit and plastic index were incresased with the increment of clay content but most of alluvial clay was appeared as a normal through non-activity clay soil shown more natural moisture content than liquid limit, and their relationship as follows : LL=0.38( cy+54.8), PI=0.836(LL -17.8), PI =0.468(LL -0.48) 7. The initial void ratio presented correlationship of positive among clay content, natural moisture content and liquid limit, and that of reverse with unit weight, and their results as follws : $e_o=0.024(w_n+0.2)$, $e_o=e_o=0.0003c_y+0.0005 LL+0.0151 W_n+\frac{3.58}{r-t}-1.52$ 8. It was shown that the compression index has correlationship of postive among the clay content, liquid limit, plastic index, natural moisture content and initial void ratio, and their relationships as follows ; $c_c=0.44(e_o-0.47)$, $c_c=0.001$

• 한국작물학회지
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• 제48권4호
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• pp.322-325
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• 2003

Controlled hydration treatment of tobacco seeds enhanced seed performance greatly without additional materials associated with conventional osmotic or solid matrix priming technique. The seeds were hydrated by adding water to a level from 10 to 60% by 5% increments and incubated for 8 days at $25^{\circ}C$. After the treatment, the seeds were dried to the original seed moisture content under $20^{\circ}C$ for 72 hours. The moisture content of tobacco seeds equivalent to 35% by the hydration treatment gave the greatest improvement in germination rate and speed compared to untreated or polyethylene glycol (PEG) primed seeds, especially at low temperature of $15^{\circ}C$.