• Journal of Biosystems Engineering
• /
• 제25권4호
• /
• pp.279-286
• /
• 2000

Most of the domestic cold storage rooms are inefficient for agricultural products because of temperature gradients inside the storage rooms. Temperature gradients are developed mainly by improper airflow pattern inside the storage room, which is a main cause of the spoilage of the agricultural products. There proper airflow pattern is essential to minimize these temperature gradients and the spoilage. The performance and characteristics of a cold storage room were determined as a function of airflow pattern and temperature distribution in forced circulation cold storage room. A commercial CFD(computational fluid dynamics) code was used to simulate 3-D airflow in the cold storage room. Solving the flow equations for the storage room, a standard k-$\varepsilon$ turbulent model was implemented to calculate steady state turbulent velocity distribution. The CFD prediction results were compared with temperature measurements inside the cold storage room. In case of pallet storage, Temperature gradients inside pallet storage was reduced because the contact area of cold air expanded through an alley of airflow in storage. But is case of bulk storage, the last temperature of storage considerably rose more than the initial temperature of storage. The reason was that bulk storage didn't include any alley of airflow in storage.

• 센서학회지
• /
• 제30권4호
• /
• pp.255-260
• /
• 2021

We studied electrochemical sensors using printed carbon nanotube (CNT) film on a polyethylene terephthalate (PET) substrate. Multiwalled CNT films were printed on a PET substrate to study its feasibility as hazardous and noxious substances (HNS) detection sensor. The printed CNT film (PCF) with a 50 ㎛ thickness exhibited a specific resistance of 230 ohm. To determine the optimum sensor structure, a resistance-type PCF sensor (R-type PCF sensor) and a conductive-type PCF sensor (C-type PCF sensor) were fabricated and compared using diluted NH₃ droplets with various concentrations. The response magnitude, response time, sensitivity, linearity, and limit of detection (LOD) were compared, and it was concluded that the C-type PCF sensor exhibited superior performance. By applying a C-Type PCF sensor, we confirmed the detection performance of 12 types of floating HNS and the response of the sensor with selectivity according to the degree of polarity.

• 센서학회지
• /
• 제31권2호
• /
• pp.90-95
• /
• 2022

The effect of the structure of an ITO nanoparticle film sensor on its performance was studied. A printed ITO film (P-ITO film) was fabricated on a flexible polyethylene terephthalate (PET) substrate, and the contact resistance of the electrode and sensor response change were clarified according to the detection position. The contact resistance between Ag and P-ITO was observed to be -204.4 Ω using the transmission line method (TLM), confirming that a very good ohmic contact is possible. In addition, we confirmed that the contact position of the analyte had a significant influence on the response of the sensor. Based on these results, the performance of the four types of sensors was compared. Consequently, we observed that 1) optimizing the resistance of the printed film, 2) optimizing the electrode structure and analyte input position, and 3) optimizing the electrode area are very important for fabricating a metal oxide nanoparticle (MONP) sensor with optimal performance.

• 센서학회지
• /
• 제31권2호
• /
• pp.85-89
• /
• 2022

We investigated a pH sensor using an Indium tin oxide (ITO) nanoparticle (NP) film printed on a flexible substrate. First, the printing precision and mechanical stability of the ITO-printed film were investigated. In particular, the factors that influence the crystallinity of ITO films were studied using X-ray diffraction pattern analysis. The response of the ITO pH sensor was calibrated using a series of standard pH solutions (pH 3-11). The pH values of various specimens were measured using an ITO pH sensor, and the results were compared with those of various pH measurement methods. As a result of the experiment, the maximum error was approximately ± 0.04 pH (0.4 %) at pH 9, which indicated that the ITO pH sensor is highly suitable for pH measurement. Finally, we used the ITO pH sensor to the measure of general specimens such as solvents and beverages and compared the results in comparison with those obtained from several conventional methods.

• 한국대기환경학회지
• /
• 제23권3호
• /
• pp.332-343
• /
• 2007

The concentrations of major volatile organic compounds (VOCs) were measured using a passive sampler in the leather industries, Shihwa and Banwol industrial complex. The leather industries were classified into four groups in raw materials and main product. The concentrations of total VOCs measured in process for ${\ulcorner}$ manufacture of reconstituted leather and special treated leather${\lrcorner}$was highest. The main VOCs measured in the leather industries was found to be toluene with a average concentration of 1,200 ppb. The major group selected in the leather industries was divided into three groups by the fingerprint analysis and the principal component analysis. The major VOCs in the groups classified by fingerprint analysis were found to be dependent on the characteristics of raw materials and main products.

• 한국문화재보존과학회:학술대회논문집
• /
• 한국문화재보존과학회 2004년도 제20회 발표논문집
• /
• pp.104-108
• /
• 2004

Species and anatomical characteristics of twenty-seven straw shoes (around AD 500s-600s) of Baekje Kingdom, excavated at Gwanbukri and Goongnamji relics of Baeje Kingdom, were examined. The shoe tissues were macerated and examined under microscope. They were identified as Typha spp (cattails), not any of straws such as rice. Cattails, a perennial glass, grow in low and swamp places. Cattails are not known as one of major raw materials for straw shoes. The cattail fibers are not as strong as those of rice straws, common raw materials for ancient shows.

• 한국실내디자인학회논문집
• /
• 제39호
• /
• pp.20-27
• /
• 2003

The purpose of this study is to provide a practical guide for selecting architectural artwork and analyze relationship between artwork and interior space & facade. The problems with many outdoor artwork did not make the characteristics of the specific environment and did not form a big flow in the urban contextualism. Choosing the artwork, architectural environment for artwork is very much part of the designers' task. When artwork is to be specifically acquired for a particular projects, designer and client must work together to make choices and plan placement. The data are collected through evaluation surveys of college students and graduate students majoring in interior architecture & design, and analyzed by using SPSS-WIN program to find the major characterized factors. It is concluded that architectural artwork should be constituted with nine major factors of interior space - theme/scale, situation/contemporay accord, finished materials harmony, line/two-three dimensional form, proportion/rhythm, sequence, natural/artificial form, abstract/reality expression, originality - and eight major factors of facade - situation, abstract/reality expression, finished materials harmony, theme/sequence, natural/artificial form, proportion/rhythm, static/dynamic expression, originality/. contemporay accord.

• Journal of the Korean Wood Science and Technology
• /
• 제34권2호
• /
• pp.22-29
• /
• 2006

On purpose to reduce accumulated moisture and to prevent moisture condensation in a light-frame wall, thermal characteristics and moisture behaviors were investigated for four different wall assemblies; a) typical wall, b) addition of vapor retarder between the insulation and the gypsum board, c) addition of air gap for natural ventilation behind the siding, d) composition with b) and c). Each wall was tested under two climate conditions; 1) $20^{\circ}C$, 50% RH (indoor) and $30^{\circ}C$, 85% RH (outdoor), 2) $30^{\circ}C$, 85% RH (indoor) and $20^{\circ}C$, 50% RH (outdoor).The results showed that the typical wall assembly had poor resistance against moisture intrusion from the inside of building. Outdoor and indoor humidity caused the moisture condensations on the inside of the siding and the back surface of the sheathing respectively. The addition of a vapor retarder did not give significant improvement in preventing the moisture intrusion.

• 한국세라믹학회지
• /
• 제43권7호
• /
• pp.408-414
• /
• 2006

Properties of slag cement that contained 50 wt% of blast furnace slag were studied when replaced blast furnace slag powder with electric arc furnace slag powder. Electric arc furnace slag was aged for about 2 months in the air by being crushed to be 1-3 mm in size. As a result of the experiment, it was proven that the water content for obtaining the same consistency became decreased as slag is replaced with electric arc furnace slag instead of blast furnace slag. Also, the workability of mortar increased about 30% at the same ratio of water to binder when blast furnace slag was completely replaced with electric arc furnace slag. The compressive strength of mortar on the 28 days increased when a slag replacement rate became 10 wt%, however, it rather decreased when the slag replacement rate exceeded 10 wt%. The heat of hydration became higher for the first 14 h in case of the replacement of slag cement by electric arc furnace slag. Yet, it decreased when 14 h had passed. Therefore, when all blast furnace slag was replaced with electric arc furnace slag, about 15 cal/g heat of hydration decreased when it passed about 72 h.

• Journal of Biosystems Engineering
• /
• 제26권1호
• /
• pp.1-10
• /
• 2001

Interactions between cage wheel and soil under the wet paddy field condition were analyzed. The cage wheel as a traction aid to driving tires of tractor was attached to the outside of the tires. The driving torque transmitted only to the cage wheel was measured and its effect on the total driving torque by both the tires and cage wheel was analyzed. Mathematical models were developed to predict the soil thrusts y a single lug and by the cage wheel with many lugs, respectively. Experimental results showed that as the diameter of cage wheel increased, positive effects of the cage wheel on the traction also increased. About 33-40% of the total traction force was obtained by the cage wheel with a diameter 1,182mm and 49-55% with a diameter 1,222mm. The peak thrust of the single lug of cage wheel increased by 31% and 59%, respectively when the diameter of the cage wheel increased from 1,182mm to 1,222mm and 1,262mm. The thrust by the cage wheel was estimated by using the developed mathematical models and the results were proved that the models are reliable for the estimation of the traction by the cage wheels.