• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.2
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• pp.250-254
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• 2007

In an attempt to find ways of improving the quality of dried Shiitake mushroom, this study compared a conveyer-type far-infrared drying method with a traditional heated air drying method. The conveyer-type far-infrared dryer was performed at air velocity of 0.6 and 0.8 m/s under drying air temperature of 60, 70 and $80^{\circ}C$, respectively. Drying characteristics, antioxidant activities and the antioxidant compounds of Shiitake mushroom dried by far-infrared dryer were investigated. Generally, drying rate with the conveyer-type far-infrared drying method was faster than that with the traditional heated air drying method. In the conveyer type far infrared drying method, drying rates were increased with increasing temperature and air velocity. The loss of antioxidant activities during the conveyer-type far-infrared drying method at 60-0.6, 60-0.8, and $70^{\circ}C-0.6m/s$ was less than the traditional drying method. However, the loss of antioxidant activities at 70-0.8, 80-0.6, and $80^{\circ}C-0.8m/s$ was higher than that of the traditional drying method. Therefore, the conveyer type far infrared drying conditions with below $70^{\circ}C$ and 0.6 m/s air velocity may produce dried Shiitake mushroom with relatively higher antioxidant activities and antioxidant compounds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.6
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• pp.629-636
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• 1991

Yellowtail fishes(Seriola quinqueeradiata) were submitted to the storages using ice-cooling($0^{\circ}C$), partial freezing($-3^{\circ}C$) and freezing $-20^{\circ}C$) method. Changes in the structures of muscle during storage at different temperatures were investigated. The ice-cooling and partial freezing storage caused early decomposition of glycogen granules and mitochondrial inner membrane, but it was accorded to much slower manner comparing with that of ice-cooling storage. The scars of ice crystals were appeared after three days of storage. The number and size of the crystal increased as progressing of the storage. They were circular and mostly located between fibers. When using the freezing storage, glycogen granules were mostly found from the muscle cell even after fourteen days of storage. Mitochonidral inner membrane maintained their integrity. The scars of ice crystals were also found, however, different from those of partial freezing storage. Their existing sites were random and their shapes were irregular. In many cases, they located in the fiber and had keen edges. Fibers were broken mostly at the Z-lines on fourteen days of storage. From these results, it was concluded that partial freezing storage can repress autolytic enzymic action and can reduce the physical damage from ice crystals which is caused by freezing.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.3
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• pp.143-147
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• 2017

To evaluate surface characteristics and improve crystalline quality of AlN single crystal grown by physical vapor transport (PVT) method, wet chemical etching process using $KOH/H_2O_2$ mixture in a low temperature condition and thermal annealing process was proceeded respectively. Conventional etching process using strong base etchant at a high temperature (above $300^{\circ}C$) had formed over etching phenomenon according to crystalline quality of materials. When it occurred to over etching phenomenon, it had a low reliability of dislocation density because it cannot show correct number of etch pits per estimated area. Therefore, it was proceeded to etching process in a low temperature (below $100^{\circ}C$) using $H_2O_2$ as an oxidizer in KOH aqueous solution and to be determined optimum etching condition and dislocation density via scanning electron microscope (SEM). For improving crystalline quality of AlN single crystal, thermal annealing process was proceeded. When compared with specimens as-prepared and as-annealed, full width at half maximum (FWHM) of the specimen as-annealed was decreased exponentially, and we analyzed the mechanism of this process via double crystal X-ray diffraction (DC-XRD).

• Journal of the Korean Chemical Society
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• v.50 no.1
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• pp.14-22
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• 2006

the basic model of chemical reactor using glow discharge, we used cathode discharge cell with vacant cavity in the middle. Currently glow discharge is widely studied as a radiation source or atomization device in atomic spectroscopy and remarkable technological achievements are made through the graft with other analysis devices such as microanalysis and steel analysis.1 Additionally, as the characteristics of basic glow discharge and radiation have been reviewed many times, those results could be used in this experiment.2-3 In 1993, an article regarding the treatment of poisonous gas in the air using low temperature plasma was published. According to this article, if DC Glow Discharge is used under continuous atmospheric flow, poisonous gases such as SO2 and NO can be removed.4 Based on those findings, we designed highly efficient reactor where stable air plasma is composed and all air flow pass the negative glow area passing through the tube. It was observed that the cathode tube type glow discharge developed in this study would be economical, easy to use and could be used as radiation source as well.

• Food Science and Preservation
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• v.7 no.4
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• pp.395-402
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• 2000

To enlarge application field of electrolyzed acid-water(EAW) on food industry, the changes of EAW properties by storage conditions and heating were investigatet. It was showed that storing EAW in closed container is mon effective to keep up the oxidation-reduction potentials(ORP), hyperchloride content and pH than stored in opened ones. ORP of EAW stored in closed container could be kept mon than 1 month as 1,150 mV levels. Ruing heating from 2$0^{\circ}C$ to 95$^{\circ}C$, ORP was increased to 1,150 mV levels at 95$^{\circ}C$ after gradual decrease to 5$0^{\circ}C$. Tyrosinase activity was decreased approximately to 26%~35% in EAW having a 950 mV~1,140 mV ORP. Also it was confirmed that EAW has anti-browning effect as sliced apple and potato, and their juices treated with EAW had conspicous difference in their $\Delta$E value. 12 kinds of pesticides such as aldrine, capful diazinon, diedrin, $\alpha$-endosulfan $\beta$-endosulfan, endosulfan sulfate, endrin, $\alpha$-BHC, o,p'-DDT, procymidone, PCNB added in EAW were recovered from ND~73.6% comparing to ones added in distilled water. The recovered amounts of pesticides, procymidone and diazinon in lettuce after soaking in EAW were 1.12 ppm and ND, compared with those of amounts soaked in distilled water were 3.67 ppm and 3.05 ppm respectively. So, it seems that EAW has potentials to promote the degradation of pesticides.

• Korean journal of applied entomology
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• v.24 no.2 s.63
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• pp.71-77
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• 1985

The male activity in Laspeyresia pomonella (L.) measured by an activity recording device in New York had two distinct peaks, the first peak at lights-off and the second one at ligts-on signal, under the defined conditions of temperature above $23^{\circ}C$ and light:dark (LD) 16:8 regime. The activity initiation of the first activity was observed four to six hours prior to the onset of scotophase and seened to be entraind by lights-off cue. Under the continuous photophase (LL) the activity period freeran with a period slightly greater than 24 hours, indicating that the rhythmicity is circadian The activity pattern was measured in eight different temperature conditions ranging from $11.3^{\circ}\;to\;30^{\circ}C$ under LD 16:8 regime. No activity was observed at $11.3^{\circ}C$ which seems to be temperature threshold for activity. The second peak of activity at lights-on signal disappeared at the temperature below $20^{\circ}C$ and the activity in scotophase was also suppressed at the temperature lower than $18^{\circ}C$. At the temperature range from $20^{\circ}\;to\;30^{\circ}C$, as temperature increased the second peak in the morning became larger and the activty in the scotophase was also increased. Because of the activity increase in the scotophase with rising temperature, the mean time of activity shifted towards the scotophase. The shift of the moth male activity period with the change of ambient temperature appears to be due to the suppression of activity under cool temperature (below $20^{\circ}C$) in scotophase.

• Korean Journal of Environment and Ecology
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• v.26 no.4
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• pp.588-592
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• 2012

To examine the reason of empty samara production of Chinese elm, Ulmus parviflora, twenty two planted trees in Wonju-si were monitered for three years in terms of their flowering, pollinatiom system and samara characteristics. Inflorescences with bisexual flowers of Chinese elm are developed in the leaf axils on the twigs. Dichogamous flowers are varied with protogynuous and protandrous flower, and stamens in some bisexual flowers are developed in seperated time on a inflorescence or a tree. It is revealed newly that the flower of Chinese elm is out-crossed and partially insect(Apis mellifera) pollinated. The ratios of sound samara are significantly differed among years, the heighest values 65.5% were shown in 2009, lowered 42.9% in 2010, and the lowest 37.5% in 2011. This result might be affected by mean daily precipitation and number of rainy days during the flowering date, and lower temperature during the floral initiation stage, especially in 2011. These findings suggest that Chinese elm has self-incompatibility strategy and much pollination failure resulted in a production of much empty samaras. Further researches on the empty-seed production strategies and pollination system of major tree species might be needed.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06b
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• pp.55-85
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• 1996

지르코니아 분말은 ZrO2 결정상이 온도변화에 따라 부피변화를 수반하는 상전이변태를 나타낸다. 단사정 ZrO2가 110$0^{\circ}C$에서는 정방정으로, 2$700^{\circ}C$ 내외에서는 입방정으로 결정구조가 가역적으로 변한다. 이 ZrO2에 금속산화물을 고용시키면 형석 (CaF2:Florite)형의 입방정 결정구조가 실온에서도 안정하게 존재하게 된다. 안정화제 산화물은 caO, MgO등 2가 산화물외에 3가 또는 4가의 금속산화물로서 Sc2O3, Y2O3, Sm2O3, Nd2O3, Gd2O3, Y2O3, CeO2 등이며 이들은 금속이온의 원자가가 변하기 쉬운 희토류 산화물이다. 안정화 지르코니아는 형석형 결정구조이며 결정화학적으로 보면 금속양이온이 산소이온에 대해서 정육면체형의 8배위를 하고 있다. 이때 이온반경비(양이온/음이온)에 따라 Zr+4자리와 O-2자리의 격자위치와 모양이 형성되므로 비틀어진 정육면체구조이건 이상적인 정육면체 형석구조를 이룬다. 이는 지르코니아의 결정상의 2상-3상인 부분안정화 지르코니아다결정체(PSZ : partially stabilized zirconia)이거나 단일상-2상인 정방정 지르코니아다결정체(TZP : tetragonal zirconia polycrystal)의 결정구조를 가지는데 기인한다. PSZ는 주로 MgO, CaO를 안정화제로 고용시켜 입방정 영역에서 소결하고 이를 다시 입방정과 정방정의 상 영역에서 열처리하여 입방정 입자내부에 정방정을 석출 형성시킨 것이며 TZP는 Y2O3 및 CeO2를 고용시켜 PSZ와 다르게 일반적인 상압소결한 정방정 결정상의 미립자이다. 산화지르코늄 분말은 지르콘사에서 열분해시킨 지르코늄소결.융해괴(caustic fusion clinker)를 산처리하여얻어진 지르코늄산용액(zirconyl acid solution : cloride, sulfide, nitride 등)으로부터 제조된다. 고순도 산화지르코늄은 용액 결정석출법에 의해 ZrOCl2.8H2O, 5ZrO2.3SO3.15H2O, ZrO(NO3)2.xH2O 등의 지르코늄 수화물만을 재결정화시킨 것으로부터 얻을 수 있으며 이 지르코늄염 수용액으로부터 입자미세구조를 효과적으로 제어하여 산화지르코늄 및 안정화 지르코니아 분말제조가 가능하다. 안정화 지르코니아 분말은 ZrO2와 안정화산화물의 고용을위하여 가열처리를 필요로 하며 일정온도에서 최적상태로 숙성하므로서 2가지 상(phase) 이상의 고용체를 가지게 된다. 안정화 지르코니아 분말은 고용처리온도를 낮추고 효과적으로 생성시키기 위해서는 지르코늄 및 안정화제염을 혼합하고 습식 직접합성하여 저온에서 고용체의 합해진상 영역을 생성시키는 것이다. 이는 지르코니아 원료분말의 미세구조를 제어하므로서 가능하며 이때 화학성분조성과 크기형태가 균일하게 분포된 입자분말을 얻을 수 있다.

• Journal of the Korean Magnetics Society
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• v.9 no.6
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• pp.271-277
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• 1999

Amorphous $Fe_{83}B_9Nb_7Cu_1$ alloy has been studied by M$\"{o}$ssbauer spectroscopy. Revised Vincze method was used and distributions of hyperfine field, isomer shift, and quadrupole line broadening of the sample at various temperatures have been evaluated and Curie temperature and $H_{hf}\;(0)$ were calculated to be 393 K and 231 kOe, respectively. Temperature variation of reduced average hyperfine field shows a flattered curvein comparison with the Brillouin curve for S=1. This behavior can be explained on the basis of Handrich molecular field model, in which the parameter Δ, which is a measure of fluctuation in exchange interactions, is assumed to have the temperature dependence ${Delta}=0.75-0.64{\tau}+0.47{\tau}^2$ where $\tau$ is $T/T_C$. At low temperature, the average hyperfine field can be fitted to $H_{hf}\;(T)=H_{hf}\;(0)\;[1-0.44\;(T/T_C)^{3/2}-0.28(T/T_C)^{5/2}-… ]$, which indicates the presence long wave length spin wave excitations. At temperature near TC, reduced average hyperfine field varies as $1.00\;[1-T/T_C]^{0.39}$. It is also found that half-width of the hyperfine field distribution was 102 kOe (3.29 mm/s) at 13 K and decreased monotonically as temperature increased. Above the Curie temperature, an average quadrupole splitting value of 0.43 mm/s was found. Average line broadening due to quadrupole splitting distribution was 0.31 mm/s at 13 K and decreases monotonically to 0.23 mm/s at 320 K, whereas that due to the isomer shift distribution is 0.1 mm/s at 13 K and 0.072 mm/s at 320 K, which is much smaller than that of both hyperfine field and quadrupole splitting. The temperature dependence of the isomer shift can be fitted within the harmonic approximation to a Deybe model with a Debye temperature ${Theta}_D=424{\pm}5K$.TEX>.

• Korean Journal of Food Science and Technology
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• v.37 no.4
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• pp.678-684
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• 2005

Extraction conditions, spectrometric, and sensory properties of pigment extracts from green discolored garlic (GDG) were studied for development of green index to evaluate degree of green discoloration of garlic. GDG pigments were extracted using polar solvents, such as methanol, ethanol, and water. Methanol with 1% HCl resulted in highest extraction of green pigments. Extraction of pigments was affected by temperature, and extracted pigments were partially destroyed at high temperatures. Optimum conditions for extraction of green pigments were $20^{\circ}C$ for 30 min. Because green pigments are unstable at room temperature, and no method has been reported to evaluate degree of green discoloration of garlic, color chart was designed by mixing varying amounts of control and GDG. High correlation was observed between sensory scores and "a" value of color chart samples (y=-3.465x - 11.676) with $R^2$ of 0.993. Green index (GI) was developed based on linear regression equation between sensory scores and "a" values. Sensory panel recognized green discoloration of garlic at $GI{\geq}3.0$. GI developed in this study could be utilized to evaluate degree of green discoloration of garlic during cold storage and distribution of garlic.