• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2002.05a
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• pp.101-101
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• 2002

현재의 세계 제지업계는 고지의 사용량과 용수의 재홀용률을 높이기 위해 노력하고있다. 특히 한국의 고지 재활용률은 세계 최고수준으로 보고된 바 있으며, 이를 사용하는 재생용지 생산업채는 고지의 높은 재활용률에 기인하는 여러 가지문제점에 당면하고 있다. 국산 고지는 반복적인 재활용으로인하여 섬유장이 짧고 매우각질화된 상태이며, 펄프 내 미세분 함량이 50%이상에 달하고 있다. 또한 섬유의 표면이 인쇄잉크, stickies 및 각종 이물질로 오염됨에 따라, 섬유자체가 보유하고 있는 섬유간 결합 능력이 저하된 상태이다. 이는 초지시, 탈수성을 악화시켜 생산성을 저하시키며, 탈수성 악화에 기인하여 충분한 고해 과정을 거치지 못하여 생산된 종이의 물리적 성질에 악영향을 미치고 있다. KOCC를 주원료로 사용하는 다겹 판지의 제조공정 또한 재활용 원료의 열악함에 기인한 초지계 내의 과다한 미세분 축적과 이로 인한 탈수성의 저하 및 건조효율의 저하를 막기 힘들었다. 이러한 탈수성 및 건조속도의 저하로 종이 생산 효율의 개선 및 각 물성의 상승을 기대하기 어려웠으며, 이를 개선하기 위하여 다양한 Polyelectrolyte를 첨가하였으나 현저한 효과를 보기 힘들었다. 이에 본 연구에서는 새로운 목질계 부원료인 Lignocell을 사용하여 초지시 탈수성 향상과 건조 촉진, 생산된 종이의 bulk 향상으로 인한 stiffness 등 물리적 성질의 향상효과를 평가하고자 하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.1-8
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• 2019

The primary purposes of this study are to understand a fundamental effects of electro-deposition on reinforcing steel in saturated Ca(OH)2 electrolyte, and evaluate the corrosion rates of rebars under cyclic 3wt.%NaCl immersion and dry corrosion environment. The three cement mortar specimens with cover thickness 5, 10 and 30mm, were prepared in the experiment. To monitor the corrosion rates of rebars in mortar, the three cement mortar specimens were exposed to 110 wet-drying cycles(8-hour-immersion in 3wt.%NaCl and 16-hour-drying in a room temperature) in the laboratory. During the wet-dry cycles, the polarization resistance, Rp, and solution resistance, Rs, were continuously measured. The instantaneous corrosion rates of rebars on the effect of electro-depositing with sat. Ca(OH)2 electrolyte were estimated from obtained R-1p and degrees of wetness were estimated from Rs values. From the experimental results, the corrosion rates of rebars were greatly accelerated by wet/dry cycles. During the mortars exposed to drying condition, the large increases in the corrosion rates were showed at all rebar surfaces in three mortar specimen, attributed from the accelerated reduction rates of dissolved oxygen in drying process. However, the corrosion rates on rebar surface electrochemically deposited with sat. Ca(OH)2 electrolyte showed the clear decreases, caused by calcium deposits in the porous rust layer.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.7
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• pp.1024-1029
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• 2010

Opuntia ficus-indica and Aloe vera slices were dried using 20, 30, and 40% polyethylene glycol (PEG) 4,000 as a dehydration agent, and the dried samples were compared with the hot-air dried and freeze dried in terms of rehydration ratio, color, and sensory evaluation. The moisture content of the PEG-treated samples decreased with increasing concentrations of polyethylene glycol. The rehydration ratio of the PEG-treated samples was better than those of the hot air-dried or freeze-dried samples. The color of the PEG-treated samples was similar to that of the freeze-dried samples and better than that of the hot air-dried samples. The sensory evaluation of PEG-treated samples was better than those of the hot air-dried or freeze-dried samples. These results suggest that dehydration of Opuntia ficus-indica and Aloe vera slices using PEG is very effective in terms of rehydration ratio and minimal damage of cell structure.

• Korean Journal of Food Science and Technology
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• v.21 no.5
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• pp.655-661
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• 1989

Optimal drying conditions consisting of air temperature and relative humidity were searched by the simulation-optimization technique for minimizing quality changes in red pepper drying. Optimized drying conditions were analysed in the viewpoint of quality change kinetics and effects of control variables on the state variables. Optimal drying conditions were nearly same in both cases for carotenoid maximization and browning minimization. In two staged optimized drying, relative humidity took a lower search limit of about 10%, and air temperature in the first stage was near the lower limit of $50^{\circ}C$ and in second stage increased to a higher temperature varying with total drying time and stage changing time. Response surface analysis of time invariable drying confirmed the location of the optimal point lying on the vertex of lower limit humidity and a lowest drying temperature which ensures to attain target moisture of 0.2g water/g dry solid. Two stage drying can attain the higher objective function of quality by 3-5% than time invariable drying for shorter total drying times.

• Journal of the Korea Society of Computer and Information
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• v.25 no.3
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• pp.185-190
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• 2020

The purpose of this study was to investigate the effects of systemic chronic inflammatory state on dry eye syndrome as a local chronic inflammatory condition. From June 16, 2016 to December 31, 2016, 726 patients who visited the general health examination center were screened using the Schirmer's test and the metabolic syndrome screening test. A total of 214 patients who were studied for hs-CRP and HbA1c were simultaneously selected for the study as well. Dry eye syndrome significantly increased in higher age groups (p<0.001) and women (p=0.020); there was no significant relationship with fasting plasma glucose, hs-CRP. In addition, as HbA1c increased the risk for dry eye syndrome also increased (β=1.960, p=0.025). Therefore, dry eye syndrome may not caused by microvascular changes in the lacrimal gland due to chronic inflammatory conditions. In diabetic patients, long-term blood glucose control may be more important than short-term blood glucose control. The high prevalence of dry eye syndrome in diabetic patients is thought to be due to autonomic dysfunction rather than microvascular changes caused by chronic inflammation.

• Water for future
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• v.29 no.6
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• pp.179-188
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• 1996

The chronical sequences of daily precipitation are of great practical importance in the planning and operational processes of water resources system. A sequence of days with alternate dry day and wet day can be generated by two state Markov chain model that establish the subsequent daily state as wet or dry by previously calculated vconditional probabilities depending on the state of previous day. In this study, a synthetic generation model for obtaining the daily precipitation series is presented by classifying the precipitation amount in wet days into multi-states. To apply multi-state Markov chain model, the daily precipitation amounts for wet day are rearranged by grouping into thirty states with intervals for each state. Conditional probabilities as transition probability matrix are estimated from the computational scheme for stepping from the precipitation on one day to that on the following day. Statistical comparisons were made between the historical and synthesized chracteristics of daily precipitation series. From the results, it is shown that the proposed method is available to generate and simulate the daily precipitation series with fair accuracy and conserve the general statistical properties of historical precipitation series.

• Solar Energy
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• v.11 no.3
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• pp.21-30
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• 1991

In-bin grain drying experiments were performed to investigate the drying characteristics between natural air and solar heated-air drying system of rough rice. A computer simulation model for solar drying system of rough rice resulted in a good agreement between the experimental and predicted moisture content. In order to save the electric energy consumption of fan, airflow rates control system using inverter was developed and resulted in the effect of energy saving.

• Journal of dental hygiene science
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• v.12 no.6
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• pp.624-633
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• 2012

This study was executed to provide the basic data that can be helpful for a program aiming at the enhancement of life quality or establishment of policy related to public health by analyzing the importance of health state among the middle-aged adults when it came to the decision of life quality. For 160 adults who were older than 40 years old, a survey was conducted and the results were derived by using t-test, one way ANOVA, and multiple regression analysis. Followings are the outcome of the study. According to such results, it was known that the level of general life quality and oral health related life quality were shown to be different depending on symptoms of depression and xerostomia. Therefore, it suggests that prevention and early intervention of depression and xerostomia will make a great contribution to improve the life quality among the middle-aged adults.

• Journal of Korean Society of Transportation
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• v.15 no.2
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• pp.25-34
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• 1997

본 연구에서는 아스팔트 포장과 콘크리트 포장의 습윤시 교통사고 가능성을 비교하 였다. 다양한 노후도를 가진 두 포장재료에 대해 마찰력 측정장비(BPT, Britsh Pendulum Tester)로 건조 및 습윤상태에서 노면마찰력을 측정하였으며, 측정결과와 두 포장재료에 대 한 실제 교통사고율을 비교하였다. 본 연구의 결과를 요약하면 다음과 같다. (1) 노면 습윤 에 따른 마찰력 저하정도는 아스팔트 포장이 콘크리트 포장보다 컸다. (2) 노면 습윤에 따른 실제 교통사고율도 아스팔트 포장에서 훨씬 큰 것으로 나타나 (1)의 결론과 일관된 결과를 보여주었다. (3) 노면마찰력은 건조상태에서는 노면마모 정도에 크게 영향을 받지 않으나 일 단 습윤상태가 되면 노면마모가 심할수록 마찰력 저하폭이 큰 것으로 나타났다.

• Journal of the Korean Wood Science and Technology
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• v.9 no.4
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• pp.1-21
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• 1981

Exterior grades of Douglas-fir and aspen plywood were impregnated with interior fire-retardant chemicals and redried under low-, intermediate-, and high-temperature drying conditions. Fire-retardant treatments included borax-boric acid, chromated zinc chloride, minalith, pyresote, and a commercial formulation. Drying processes included kiln and press-drying. Evaluated were drying rates and defects generated. The borax-boric acid and the commercial treatments redried at rates similar to water-treated controls. Other salt treatments were significantly slower drying and more defect prone. Chromated zinc chloride treatment was consistently the slowest drying and most defect prone. Press drying was three times faster at an equivalent temperature level. However, thickness shrinkage doubled because of 50 1b/in. platen pressure.