• Fire Science and Engineering
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• v.15 no.2
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• pp.1-5
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• 2001

We had investigated combustion properties of starch. Decomposition of starch scavenged by pre-cipitator of spinning factory with temperature were investigated using DSC and TGA. Combustion properties of starch according to amount were checked as temperature variation according to time using spontaneous ignition apparatus. Moreover, combustion properties with blowing or without blowing condition were checked in spontaneous ignition apparatus. As results of thermal analyses, increase in raising temperature causes initial smoldering temperature to move towards low temperature section. In addition, as amount of starch was increased, initial smoldering temperature was lowered. All of combustion forms were smoldering combustion. Initial smoldering temperature was low more slightly with blowing condition than without blowing condition in spontaneous ignition apparatus, which condition made heating value high.

• Nuclear Engineering and Technology
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• v.36 no.4
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• pp.357-363
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• 2004

A prototype long pulse ion source was developed, and the beam extraction experiments of the ion source were carried out at the Neutral Beam Test Stand (NBTS) of the Korea Superconducting Tokamak Advanced Research (KSTAR). The ion source consists of a magnetic bucket plasma generator, with multi-pole cusp fields, and a set of tetrode accelerators with circular apertures. Design requirements for the ion source were a 120kV/65A deuterium beam and a 300 s pulse length. Arc discharges of the plasma generator were controlled by using the emission-limited mode, in turn controlled by the applied heating voltage of the cathode filaments. Stable and efficient arc plasmas with a maximum arc power of 100 kW were produced using the constant power mode operation of an arc power supply. A maximum ion density of $8.3{\times}10^{11}\;cm^{-3}$ was obtained by using electrostatic probes, and an optimum arc efficiency of 0.46 A/kW was estimated. The accelerating and decelerating voltages were applied repeatedly, using the re-triggering mode operation of the high voltage switches during a beam pulse, when beam disruptions occurred. The decelerating voltage was always applied prior to the accelerating voltage, to suppress effectively the back-streaming electrons produced at the time of an initial beam formation, by the pre-programmed fast-switch control system. A maximum beam power of 0.9 MW (i.e. $70\;kV{\times}12.5\;A$) with hydrogen was measured for a pulse duration of 0.8 s. Optimum beam perveance, deduced from the ratio of the gradient grid current to the total beam current, was $0.7\;{\mu}perv$. Stable beams for a long pulse duration of $5{\sim}10\;s$ were tested at low accelerating voltages.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.117-119
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• 2017

The multi-stage catalytic igniter for hybrid rocket auto ignition is described in this paper. After charging the catalyst and pre-heating the first stage, the $N_2O$ was supplied at the first stage with the low mass flow rate, and then the $N_2O$ with the high flow rate was supplied into the second stage. Even though the $N_2O$ flow rate was high, it was decomposed by supplying the high temperature gas which was evolved from the $N_2O$ decomposition in the first stage. This multi-stage ignitor resulted in the decrease of the ignition time in comparison with the previous ignitor, and confirmed the possibility of $N_2O$ decomposition with the high flow rate using the multi-stage catalytic-ignition system.

• 전자공학회논문지 IE
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• v.43 no.1
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• pp.5-15
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• 2006

In this paper, we measured the biosignal using hot-water system(STYX ford202) on foot. The biosignal transition data is observed from hot-water thermotherapy on foot. pre and post demonstration conditions under 43$^{\circ}C$ and 45$^{\circ}C$ are checked about 9 physiological factors for 10 persons and 10 days. (Checking Time: pre-test, post-test(5, 10, 15, 20 minutes)). The biosignal transition of demonstration's results showed as belows; Forehead Temperature($^{\circ}C$): -0.69 $\pm$ 0.01 dec, Leg Temperature($^{\circ}C$): 1.51 $\pm$ 0.22 inc, Blood Flow($m\ell/min$): 1.18 $\pm$ 0.50 inc, Blood Pressure(mmHg): (max) -1.49$\pm$ 2.81, (min) -0.06 $\pm$ 0.13 dec, Heart Rate(bpm): 6.97 $\pm$ 0.72 inc, Blood Sugar($mg/d\ell$) : -2.41 $\pm$ 1.55 dec, Oxygen Saturation(%): 1.34 $\pm$ 0.28 inc, Body Fat(%) -1.75 $\pm$ 0.15 dec, Weight(kg): -0.10 $\pm$ 0.04 dec. (dec: decrease, inc: increase)

• Journal of the Korean Vacuum Society
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• v.18 no.4
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• pp.318-330
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• 2009

A high heat flux test facility using a graphite heating panel was constructed and is presently in operation at Korea Atomic Energy Research Institute, which is called KoHLT-1. Its major purpose is to carry out a thermal cycle test to verify the integrity of a HIP (hot isostatic pressing) bonded Be mockups which were fabricated for developing HIP joining technology to bond different metals, i.e., Be-to-CuCrZr and CuCrZr-to-SS316L, for the ITER (International Thermonuclear Experimental Reactor) first wall. The KoHLT-1 consists of a graphite heating panel, a box-type test chamber with water-cooling jackets, an electrical DC power supply, a water-cooling system, an evacuation system, an He gas system, and some diagnostics, which are equipped in an authorized laboratory with a special ventilation system for the Be treatment. The graphite heater is placed between two mockups, and the gap distance between the heater and the mockup is adjusted to $2{\sim}3\;mm$. We designed and fabricated several graphite heating panels to have various heating areas depending on the tested mockups, and to have the electrical resistances of $0.2{\sim}0.5$ ohms during high temperature operation. The heater is connected to an electrical DC power supply of 100 V/400 A. The heat flux is easily controlled by the pre-programmed control system which consists of a personal computer and a multi function module. The heat fluxes on the two mockups are deduced from the flow rate and the coolant inlet/out temperatures by a calorimetric method. We have carried out the thermal cycle tests of various Be mockups, and the reliability of the KoHLT-1 for long time operation at a high heat flux was verified, and its broad applicability is promising.

• Korean Journal of Environmental Agriculture
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• v.15 no.1
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• pp.91-104
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• 1996

The viability loss or death of weed seeds buried in soil can be induced by infrared irradiation which has good penetration in moist soil. By using this principle of pre-emergence soil-treatment, the study was carried out to obtain basic information needed to develop the effective weed control method for the production of less polluted agricultural products. An apparatus for irradiating infrared was constructed by using ceramic material with high emissivity. The LPG was used as fuel for producing infrared by heating ceramic material. The soil heated in this study was loam with four levels of moisture contents (0.6, 5.7, 10.7, 15.1 % wb). The temperature distribution was measured at various soil depths when soil with different moisture content was irradiated with infrared for three different times (30, 60, 90 sec). The soil depths with duration time of minimum 3 minutes over $80^{\circ}C$, temperature inducing viability loss of weed seeds, were investigated. When the moisture content of soil was 0.6 and 5.7 % wb, the soil depths which can induce viability loss of weed seeds was greatly increased with increasing irradiation time. However, any depths of soil tested in this study was not reached to the temperature of $80^{\circ}C$ when 30 seconds of irradiation time was applied on soil with moisture content of 10.7 or 15.1 % wb. Generally, the soil depth needed for viability loss of weed seeds was decreased with increasing moisture content of soil. Also, longer irradiation time was required to induce viability loss of weed seeds with increasing moisture content of soil.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.56-62
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• 2015

Various pretreatment methods were evaluated to prevent tissue softening of heated onion. Changes in onion tissue firmness during heating were explained by 3-mechanism model consisting of texture hardening at low temperature ($60-80^{\circ}C$) and substrate softening at high temperature. Preheating of onion in a $Ca^{2+}$-containing solution significantly improved its texture after high-temperature heating. The improvement of firmness by preheating at low temperature was related to the formation of strong cross-linking between carboxyl groups and $Ca^{2+}$ by the action of pectin methylesterase in onion. The highest firmness was obtained by pre-heating at $70^{\circ}C$ for 120 min in 0.5% calcium solution. This result was supported by chemical analysis showing that the amount of bound calcium was the highest at $70^{\circ}C$. Further investigation should be carried out to establish the optimal conditions to prevent the softening of various vegetables.

• Journal of Nutrition and Health
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• v.38 no.3
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• pp.232-241
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• 2005

Today, the role of kindergarten is more important as nutrition provider through snack and meal services. Desirable kinds and amounts of food items at school lunch menu were important factors of nutrients intakes in children. This study was performed to assess the kindergarten's meal service program (snack and lunch) and the consumption amount of lunch according to each dishes. Twenty four institutions that cared over one hundred children were observed at Seoul and Kyunggido area. Well-trained observers checked meal and snack serving activity and foodservice facilities by formal checklist. And using the weighing method assessed the consumption levels of food items at lunch. During 3 days, 30 children in each kindergarten were selected randomly according to age, observers measured serving and residual weight of each food. The data was compiles by performing ANOVA-test using SPSS WIN 10.0. The result were as follows: 1) Foodservice facilities in kindergarten was limited to provide qualified foodservice. $91.7\%$ of institution had kitchen, $41.7\%$ had dinning. The kitchen equipment possession rate was $12.5\%$ (oven), $30.8\%$ (heating cabinet), $58.3\%$ (refrigerator). The rate of using document about foodservice was used $83.3\%$ (menu list), $41.7\%$ (daily foodservice record), $25\%$ (standard recipe). $41.7\%$ of institution employed licensed dietitian. Only $41.7\%$ of subjects preserved meal after daily meal service. 2) Meal serving size was decided by teacher, $54.5\%$ at snack and $43\%$ at lunch and pre-divided individual portion type was $36.4\%$ at snack and $28.6\%$ at lunch. The rate of cleaning activity before meal was $72.2\%$ at snack, $90.5\%$ at lunch. And nutrition or sanitation education activity was more performed at lunch time, for examples brushing teeth activity was $12.5\%$ at snack $85.7\%$ at lunch. 3) The consumption amounts of plain cooked rice was $112.7{\pm}26.1{\cal}g$, cooked rice and cereal was $93.06{\pm}27.97{\cal}g$, curry rice was $208.35{\pm}64.84{\cal}g$ and the consumption amounts of these main dishes was significantly different by age (p < 0.001). The consumption amounts of soup was very different according to children's preference. The consumption amounts of seaweed soup was $120.18{\pm}82.13{\cal}g$, wild sesame and bean-paste soup was $40.64{\pm}23.16{\cal}g$. The consumption range of kimchis was from $6{\cal}g\;to\;13{\cal}g$, jorim (braised food) was from $3{\cal}g\;to\;25{\cal}g$, fried food (include stir fried, deep fat fried, pan fried) was from $14.5{\cal}g\;to\;22{\cal}g$, vegetable dish was from $3{\cal}g\;to\;16{\cal}g$. These consumption amount of each dishes was not reached recommended portion size of nutritionally planning menu by nutritionist.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.2
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• pp.269-276
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• 2016

This study was conducted to determine the inactivation effects of slightly acidic electrolyzed water (SAEW) on microorganisms attached to salted Chinese cabbage and food materials of kimchi, such as slice radish and green onion. In addition, changes in microbial and physicochemical quality of manufactured kimchi during storage at $4^{\circ}C$ for 4 weeks were investigated. Compared to the untreated control with tap water, total bacterial counts (TBC) of Chinese cabbage, slice radish, and green onion were reduced by 1.75, 1.68, and 1.03 log CFU/g at dipping times of 20 min, 5 min, and 10 min, respectively, upon treatment with 30 ppm SAEW at $40^{\circ}C$. Effect of microbial inhibition was higher in salted Chinese cabbage brined in 10% salt (w/v) of 30 pm SAEW at $40^{\circ}C$ than in untreated control with tap water, as indicated by 1.00 log CFU/g reduction. TBC of kimchi manufactured with materials treated with 30 ppm SAEW at $40^{\circ}C$ was not significantly affected compared to untreated control, although coliforms were remarkably reduced compared to the untreated control. At the beginning of storage (1 weeks), TBC and lactic acid bacteria (LAB) counts increased by approximately 9 and 7.66~8.18 log CFU/g, respectively, and coliforms were completely eliminated. The pH and acidity of kimchi at 2 weeks were 4.34~4.49 and 0.55~0.66%, respectively, and then slowly decreased. The texture (firmness) of kimchi decreased with storage time, but the difference was not significant. This combined treatment might be considered as a potentially beneficial sanitizing method for improving the quality and safety of kimchi.

• International Journal of Ocean System Engineering
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• v.2 no.3
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• pp.185-194
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• 2012

A Macroscopic combination of two or more distinct materials is commonly referred to as a "Composite Material", having been designed mechanically and chemically superior in function and characteristic than its individual constituent materials. Composite materials are used not only for aerospace and military, but also heavily used in boat/ship building and general composite industries which we are seeing increasingly more. Regardless of the various applications for composite materials, the industry is still limited and requires better fabrication technology and methodology in order to expand and grow. An example of this is that the majority of fabrication facilities nearby still use an antiquated wet lay-up process where fabrication still requires manual hand labor in a 3D environment impeding productivity of composite product design advancement. As an expert in the advanced composites field, I have developed fabrication skills with the use of machinery based on my past composite experience. In autumn 2011, the Korea government confirmed to fund my project. It is the development of a composite sanding machine. I began development of this semi-robotic prototype beginning in 2009. It has possibilities of replacing or augmenting the exhaustive and difficult jobs performed by human hands, such as sanding, grinding, blasting, and polishing in most often, very awkward conditions, and is also will boost productivity, improve surface quality, cut abrasive costs, eliminate vibration injuries, and protect workers from exposure to dust and airborne contamination. Ease of control and operation of the equipment in or outside of the sanding room is a key benefit to end-users. It will prove to be much more economical than normal robotics and minimize errors that commonly occur in factories. The key components and their technologies are a 360 degree rotational shoulder and a wrist that is controlled under PLC controller and joystick manual mode. Development on both of the key modules is complete and are now operational. The Korean government fund boosted my development and I expect to complete full scale development no later than 3rd quarter 2012. Even with the advantages of composite materials, there is still the need to repair or to maintain composite products with a higher level of technology. I have learned many composite repair skills on composite airframe since many composite fabrication skills including repair, requires training for non aerospace applications. The wind energy market is now requiring much larger blades in order to generate more electrical energy for wind farms. One single blade is commonly 50 meters or longer now. When a wind blade becomes damaged from external forces, on-site repair is required on the columns even under strong wind and freezing temperature conditions. In order to correctly obtain polymerization, the repair must be performed on the damaged area within a very limited time. The use of pre-impregnated glass fabric and heating silicone pad and a hot bonder acting precise heating control are surely required.