• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.3
• /
• pp.866-872
• /
• 2010

In this paper, we developed a digital soldering station based on PID controller, which supply stable power by controlling the current of heater of soldering iron. The proposed system designed PID controller to converge quickly to the set up temperature by user, and regain the lost of heat by external factors quickly. PID controller, designed by Ziegler-Nichols' tuning method, decides triac's trigger timing using setting temperature and present temperature to control the phase of AC 24V power that supply to the heater. Also, we give the function that shows present temperature and setting temperature of iron, and working time by graphic LCD. And during the rest time, we decided the power saving and extension of iron tip by dropping to the optimal temperature. Two experiments had implemented in $25^{\circ}C$ laboratory to confirm the performance of proposed method. The first experiment took 12sec, 13sec, 16sec, 18sec, reaching to $200^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$, $480^{\circ}C$ respectively which result showed shorten of rising time than previous method. In the loading experiment of $300^{\circ}C$, $400^{\circ}C$, $480^{\circ}C$ steady state showed temperature drop of $3.8^{\circ}C$, $4.1^{\circ}C$, $4.5^{\circ}C$ which result showed the low temperature deviation than previous method.

• Resources Recycling
• /
• v.18 no.2
• /
• pp.3-15
• /
• 2009

To accomplish the greenhouse gas reduction which is over core unit project of the "Green growth" policy and "Resource circulation society", it is important to maintain proper balance and complement between energy recovery from waste and material recycling. This research(study) examined the related policies on the past of korea and foreign country, and also "The 4th resource recycling master plan" and "Energy recovery from waste plan" to provide advisable direction for resource recycling policy. The results of the research(study) showed that there were no significant difference between korea and developed foreign countries waste management policies. But in German policy, energy recovery from waste and pre-treatment are importantly considered and highly required for permission. Under current circumstance in korea, recycling will be more difficult than in the past. According to "The 4th resource recycling master plan", film type of synthetic resin was not sustainable recycled material in substance."Energy recovery from waste plan", proved that the energy recovery from RDF/RPF have lower efficiency than regular incineration generation and substance recycling. To solve these problems, the energy and remainder heat recovery must be generalized to "Energy recovery" concept and institutional improvement such as LCA(Life Cycle Assessment) system are need to support it. And also technology development to extract synthetic polymer by dissolved film type of synthetic resin must be provided.

• Polymer(Korea)
• /
• v.24 no.3
• /
• pp.389-398
• /
• 2000

Transparent, abrasion resistant coatings with 4~13 ${\mu}{\textrm}{m}$ thickness were prepared by spin-coating on polycarbonates with organic/inorganic hybrid solutions, followed by UV curing and heat treatment at 12$0^{\circ}C$ for 12 hours. The coating solutions were composed of inorganic phase and organic phase in 0:100, 20:80, 30:70, 50:50, 80:20 wt% ratios, respectively, mixed with photoinitiator, senaitizer and surfactant. The inorganic phase was formed by sol-gel reaction of TEOS and silane coupling agent MPTMS in 1 : 2 or 2 : 1 molar ratios, the organic phase consisted of difunctional urethane acrylate oligomeric resin, multifunctional acrylate TMPTA and HDDA in 4 : 3 : 3 wt% ratio. The coating systems were investigated by FT-IR, $^{29}$ Si-NMR spectra. In addition, TGA/DSC for thermal analysis and SEM, AFM observation for coated surface were examined. Gererally, the homogeneity of phases, the surface smoothness of coating and abrasion resistance were improved with the higher content of inorganic component. Namely, coating system with below 10 $\AA$ surface roughness and T$_{g}$ of 15$0^{\circ}C$ showed only 10% decrease in light transmittance after abrasion test, whereas uncoated polycarbonate substrate exhibited 46% decrease..

• Journal of the Korean Wood Science and Technology
• /
• v.40 no.1
• /
• pp.10-18
• /
• 2012

A high airtightness is required for the residential spaces constructed recently to save cooling and heating energy through improving insulation performance. Because the chances to release steam formed by human activity in building and inflow of water vapor in outdoor air to residential space are reduced, the natural humidity control performance of interior materials has become more important. In this study, hygroscopic performance of thermo-physically treated wood (Pinus koraiensis) was estimated. At various relative humidity condition, the water vapor adsorption and desorption rates of wooden materials were measured as well as equilibrium moisture content. Effects of roughness and surface microstructure as physical factors and functional groups as chemical factors on the hygroscopicity were analyzed. It is expected that the results from this study and further study of measuring moisture generation in residential spaces could contribute to install a system for evaluating the hygrothermal performance of wooden building.

• Fire Science and Engineering
• /
• v.31 no.4
• /
• pp.103-110
• /
• 2017

With the common tendency in the accordance with the trend, low-stories built edifices that are Pilotis-oriented structured exponentially and constantly increasing its number of buildings. It inevitably contains its risks of facing conflagrations as most of its part is used as parking lots. In the parking lots, the length of the flame has a heavy-weighted possibility that it would get increased because the heat release rate gets relatively high due to the vehicle insulation. Following on top of that, due to the nature of the Pilotisconsisting of pillars, there is a risk of flame spread to the adjacent building if the same Pilotis-structured buildings are adjacent to each other, if the flame spreads to the surroundings due to the influence of the wind. Because the most of the pilotis-structured-buildings have this entrance that makes the residents be able to enter, if the entrance were plugged the resident get a serious risk of a poisonous gas and a flame. Therefore, if the parking-lots of the pilotis-structured-buildings are adjacent to each other it requires a space to prevent the place from the spread of flame. This research studied how far is appropriate to prevent flame spreading with FDS. As a result, the study found that the distance at least 3.0 m is required.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.5
• /
• pp.769-777
• /
• 2004

A Helicobacter pylori urease inhibitor from Rubus coreanus Miquel has been isolated and partially characterized for aiming to Prevent H. pylori growth and decrease harmful accumulation of ammonia in human gastric mucosa. We screened urease inhibitory activities in 519 extracts library prepared by solvent extraction from 173 kinds of edible plants, medicinal herbs, herbs and seaweeds using a colorimetric urease assay system. As results of primary and secondary screening, 70% acetone extract of Rubus coreanus Miquel was selected as potent candidate, showing about 24% inhibitory activity. The acetone extract was sequentially partitioned into RCE/RCWI and RCB/RCW2 layers with ethyl acetate and butanol. The major active component in RCW2, water layer from butanol fractionation was revealed to be peptidic or proteinous substance by inhibitory activity determination after pronase digestion and periodate oxidation. RCW2-IIIc a was isolated by sequential column chromatography on DEAE-Toyopearl 650C, Butrl-Toyopearl 650M and Sephadex LH-20. The isolated urease inhibitor RCW2-IIIc $\alpha$, was highly pure proteinous substance with molecular weight of 13kDa by high-performance gel permeation liquid chromatography. RCW2-IIIc$\alpha$ has about 5 times higher inhibitory activity than 70％ acetone extract, showing high stability against heat treatment and peptic digestion.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.20 no.5
• /
• pp.447-454
• /
• 1991

Chopped garlic was added to beef to determine its effect on the protein digestion during storage and heat treatment. The digestibility of raw beef without garlic was not significantly changed during storage at $4^{\circ}C$, but increased as garlic added and aging time increased. The optimal aging time and amount of garlic added was varied with heating time. Trypsin inhibitor did not change the digestibility of beef due to its thermal inactivation. Gel chromatography revealed that the lower molecular weight peptides(2,200~6,150 dalton) were shown in beef-garlic mixture through aging and heating procedure. When aged beef with garlic was digested with four-enzyme system, the soluble portion was increased significantly in comparison with that from raw beef without garlic. Protein quality of beef, as measured by computed PER(C-PER), was improved from 2.14 of raw beef to 2.50 of aged beef with chopped garlic.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.28 no.3
• /
• pp.1-10
• /
• 2015

Objectives Diagnosis System of Oriental Medicine (DSOM) was made as a computerized assistant program for oriental medicine doctors to be able to diagnose with statistical basis. Then DSOM uses questionnaires filled out by respondents with explanatory guide. But if the respondents misunderstand the meaning of the passages, the results were quite the opposite. Methods This study was designed to investigate the diagnostic correspondent rates between DSOM and TKM practitioners. First, let the respondents answer to DSOM. After that, three doctors diagnosed the respondents and marked 'p' when they diagnose that the respondent had the pathogenic factors, marked 'n' when they diagnose that the respondent had the pathogenic factors but not severs, and did not marked when they diagnose that the respondent didn't have the pathogenic factors. Finally, this study was investigated the correspondent rates of diagnosis between DSOM and doctors. Results In the pathogenic factor of three including insufficiency of Yin (陰虛), the correspondent rates were 90%. In the pathogenic factor of nine including deficiency of qi (氣虛), the correspondent rates were 80%. In the pathogenic factor of four including blood stasis (血瘀), the correspondent rates were 70%. In HH and HL, they showed the correspondent rates of 61.77%. The correspondent rate of heat (熱) was highest (96.88%). The correspondent rate of insufficiency of Yang (陽虛) was lowest (0%). In LH and LL, they showed the correspondent rates of 88.31%. The correspondent rate of blood stasis (血瘀) was lowest (71.76%). They all showed the correspondent rates of over 70%. Conclusions In DSOM and Doctors' diagnose, they showed the correspondent rates of 83.60%.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.24 no.6
• /
• pp.745-756
• /
• 2022

The road tunnel is a semi-closed space that is blocked on all sides except the entrance and exit, and in the event of a fire, the smoke of the fire spreads longitudinally due to heat buoyancy caused by the fire and air currents that always exist in the tunnel. To solve this problem, smoke removal facilities are installed in road tunnels to secure a safe evacuation environment by controlling the direction of movement of smoke or directly smoking at fire points. In urban areas, the service level of urban roads decreases due to the increase in traffic due to the increase in population, and as a solution, the construction of underground roads in urban areas is increasing. When a fire occurs during hydrogen leakage through TPRD of a hydrogen fuel cell vehicle (FCEV), the fire intensity depends on the amount of leakage, and the maximum fire intensity depends on the orifice diameter of the TPRD. Considering the TPRD orifice diameter of 1.8 mm, this study analyzed the diffusion distance of fire smoke according to the wind speed of the roadway and the opening interval of the large exhaust port when the maximum fire intensity was 15 MW. As a result, it was analyzed that air flow in the tunnel could be controlled if the wind speed of the road in the tunnel was less than 1.25 m/s, and smoke could be controlled within 200 m from the fire if the damper interval was 50 m and 100 m.

• Journal of the Korea Convergence Society
• /
• v.12 no.12
• /
• pp.145-151
• /
• 2021

This study aimed to investigate the efficient conduct of HA coating on Ti Gr4 for the practical use of medical device. Ti Gr4 alloy specimens measuring 𝜱 25mm × 1mm were sprayed with hydroxyapatite using thermal spray according to ASTM F1185-88. The surface was evaluated at #120, #400, #1,000 sandpaper and barrel finishing. Each coating properties was analyzed using SEM, UTS 20,000psi cap. and in vitro cytotoxicity. Surface morphology consists of well molten particles with very little resolidified or unmolten areas. The average Ca/P ratio is 1.74 which is in good agreement with theoretical value of 1.67. The average roughness Ra is very representative of roughness of specimen. The coatings are dense and well adhered to the substrate. The average bond strength was 61.74 MPa with a standard deviation of 4.06 which indicates fairly reliable results for ASTM 633 type tests. Variations in results from jig design, epoxy used, crosshead speeds etc. in vitro cytotoxicity result had a Grade 3. The results of the study are expected to be helpful in osseointegration and plasma-spray HA coated Ti Gr4 are more satisfactory in HA coating thickness elevation which is preferable to any other system.