• 한국결정성장학회지
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• 제28권5호
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• pp.199-205
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• 2018

IGCC(integrated gasification combined cycle) 발전소에서 발생된 석탄회로부터 발포 및 비발포 지오폴리머를 제조하고, 그 내수성을 평가하였다. 시편을 30일간 물에 침지하여 미세구조 변화 및 침지액의 알칼리도 변화를 측정함에 있어 지오폴리머 발포여부, 상온재령 조건, 그리고 침지시간을 변수로 실험하였다. Si-sludge를 0.1 wt% 첨가한 지오폴리머에는 직경이 1~3 mm인 기공들이 발생하여 우수한 발포성을 보였고, calcium-silicate-hydrate 결정상이 생성되었다. 침지실험에서 침지액의 pH가 시간에 따라 증가하는 것은 경화제로 사용된 알칼리 활성화제 중에서 미반응된 것이 물에 녹아나왔기 때문이다. 침지액의 pH 변화로부터 발포된 시편이 제조과정에서 비발포 시편에 비해 지오폴리머 반응이 더 빨리 완결됨을 알 수 있었다. 본 연구를 통하여 IGCC 석탄회를 재활용한 발포 및 비발포 지오폴리머를 성공적으로 제조할 수 있었으며, 향후 내수성이 필요한 분야에 IGCC 석탄회 기반 지오폴리머를 적용하기 위해 필수적인 상온재령 시간, 발포/비발포 유무, 침지 시간 등에 대한 공정 데이터들을 확보하였다.

• 한국콘텐츠학회논문지
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• 제13권11호
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• pp.665-676
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• 2013

이 연구에서는 한국콘텐츠진흥원에서 실시한 "게임과몰입 종합 실태조사" 원자료의 2차 분석을 통해 심리 특성이 게임 과몰입에 미치는 영향을 파악하였다. 심리 특성은 정서안정, 자존감, 의지력, 행복감이라는 4개 유형으로 구분되며 연령, 성별, 경제수준, 여가활동 다양성, 친구/가족 관계, 게임이용시간과 함께 독립변인으로 하여 심리불안, 대인관계지장, 일상생활지장, 게임시간 및 욕구통제력 상실이라는 4개의 과몰입 유형에 미치는 영향을 분석하였다. 그 결과 심리 유형과 인구학적 변인, 게임 이용시간, 친구/가족 관계, 여가활동의 다양성 등이 게임 과몰입에 상당히 영향을 미치는 것으로 나타났다. 심리 유형 중 정서적 안정과 자존감 순으로 부(-)의 영향을 미친 것으로 분석되었는데 이는 정서적 안정과 자존감 제고가 게임 과몰입의 위험성을 줄이는데 중요한 요소가 됨을 의미한다. 이를 토대로 어린이, 청소년의 게임 과몰입 문제 해소를 위한 방안들이 논의되었으며 후속 연구 아이디어가 제시되었다.

• 한국결정성장학회지
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• 제31권4호
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• pp.174-181
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• 2021

순환자원인 IGCC 슬래그와 Si 슬러지를 활용하여 경량 지오폴리머를 제작하였다. 양생방법 및 침지기간에 따른 압축강도 및 밀도의 변화를 관찰하기 위해 세 가지 양생 방법을 시도하였고, 장기공용성 확인을 위해 침지 기간을 21일까지 변화시켰다. Oven(건조기) 양생 시편의 경우, 침지 기간이 증가할수록 압축 강도가 급격하게 감소하였다. 오토클레이브(autoclave)에서 양생된 시편은 3일과 7일에서는 낮은 압축 강도를 보이다 21일에서 급격한 증가를 보인 반면, 오토클레이브에서 양생 후 oven에서 양생한 시편은 반대로 3일과 7일에서 높은 압축 강도를 보였으나, 21일에서 급격한 감소를 보였다. 따라서 초기강도 발현을 위해서는 oven을 이용한 양생이 효과적이나, 장기간 물에 침지할 경우에는 오토클레이브를 이용한 양생이 바람직 한 것으로 사료되었다.

• Preventive Nutrition and Food Science
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• 제8권3호
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• pp.230-234
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• 2003

Mass transfer characteristics during osmotic dehydration of carrots were studied as functions of immersion temperature and time, and sugar and salt concentrations. The effect of osmotic dehydration on the degree of browning of air-dried carrots was also evaluated. Increasing the immersion temperature and time, sugar concentration, and salt addition increased water loss, sugar gain, molality and rate of dehydration. The water loss and increases in solids, and molality were rapid in the beginning of the process and then increased slowly during remainder of the process. Increasing 1 or 2% salt concentration in the 40$^{\circ}$Brix sugar solution at 6$0^{\circ}C$ increased water loss and solid gain. Salt addition was not able to significantly affected on water loss and solid gain compare to temperature (40～8$0^{\circ}C$) and sugar concentration (20～60$^{\circ}$Brix) changes due to the low salt concentration. A minimum degree of browning of the air-dried carrots (O.D. = 0.048) could be achieved using binary solutions (40$^{\circ}$Brix sugar solution with 2% salt addition) with 24 min of immersion time compared to control (O.D. = 1.308) or blanching with 24 min of immersion time (O.D. = 0.174).

• 한국해양공학회지
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• 제20권2호
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• pp.52-58
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• 2006

The effect of various environmental conditions on the durability of E-glass fiber/vinylester resin composites have been investigated using the tensile test specimen of strand type. It was found that the durability test method performed by the stand type specimen was more convenient and reliable than other conventional test method. The weight gains increased with the immersion time in both water and alkaline solution, and the Weight gains at $50^{\circ}C$. were much bigger than those at $20^{\circ}C$ in both conditions. The tensile strength decreased with the pass of immersion time in all aqueous solution, and the tensile strength at $80^{\circ}C$ in alkaline solution decreased very steeply at beginning of immersion time. The decrement of tensile strength according to the immersion time in various environmental conditions was mainly caused by the degradation of interface and the damage of glass fiber surface.

• 한국식품영양과학회지
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• 제27권5호
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• pp.903-907
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• 1998

Mass transfer characteristics during osmotic dehydration of mushrooms(Agaricus bisporus) in sugar solution were studied as a function of sugar concentration, immersion time and temperature, and the effect of osmotic dehydration on browning inhibition of air-dried mushrooms was also evaluated. Increasing the sugar concentration, immersion time and temperature increased moisture loss, sugar gain, molality and rate parameter. The changes of sugar gain and rate parameter were more significantly affected by concentration than by temperature of sugar solutions, while 1$0^{\circ}C$ increase in temperature or 10 Brix increase in concentration had the same effect on water loss. Water loss, sugar gain, molality were rapid in the first period of osmotic dehydration especially in the case of higher concentration and temperature of sugar solutions. Effects of osmotic dehydration in sugar solution(60 Brix, 8$0^{\circ}C$) with 18 min of immersion time(O.D.=0.099) rior to air dehydration on browning inhibition of dried mushrooms were more significant than blanching in water(8$0^{\circ}C$) with the same immersion time(O.D.=0.330) and the control (O.D.=0.559).

• 한국해양공학회지
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• 제13권4호통권35호
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• pp.63-74
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• 1999

This study has been investigated about the influence of moisture environment on the mechanical properties in the carbon fiber cross laminates. And it has been also investigated the effect of unit ply thickness of the carbon fiber cross laminates on the mechanical properties in distilled water of $80^{\circ}C$ for a certain period of time. As a results, it was found that the weight gain of water was increased with the immersion time and the bending strength and fracture toughness were decreased with the weight gain of water. And it was also shown that the bending strength and fracture toughness were decreased with the increasing of the unit ply thickness of carbon fiber cross laminates through the immersion time.

• 한국정밀공학회지
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• 제23권12호
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• pp.128-134
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• 2006

Two-dimensional nano-patterns are fabricated using immersion holographic lithography. The photoresist layer is exposed to an interference pattern generated by two incident laser beams($\lambda$=441.6 nm, He-Cd laser) of which the pitch size is less than 200 nm. Good surface profiles of the 2 dimensional patterns are achieved by trimming the lithography process parameters, such as, exposure time, developing time and refractive index of medium liquid.

• Restorative Dentistry and Endodontics
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• 제6권1호
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• pp.77-81
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• 1980

The author has studied comparatively the sealing quality of conventional Z.O.E. cement, Kerr sealer and Nogenol sealer by means of penetration of 2% methylene blue solution through the root apex of human teeth in 72 cases as time elapsed. The results were as follows; 1. All the specimens, whose dye immersion time is two days, showed dye penetration of low degree unrelated to the kinds of root canal sealer. 2. Kerr sealer group, like conventional Z.O.E. group, showed dye penetration of high degree related to increased time of immersion in the dye. 3. In Nogenol group, there was slight increase in penetration related to increased time of immersion in the dye. 4. Kerr sealer group showed comparatively lower grade of dye penetration than conventional Z.O.E. and higher than Nogenel sealer.

• PNF and Movement
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• 제16권2호
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• pp.259-266
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• 2018

Purpose: This study aimed to compare balance ability according to the immersion level of virtual reality-based training for the balance enhancement of the elderly. Methods: This study included 48 elderly people aged 65 years and older (male 16, female 32). According to the immersion level of applied virtual reality training, 16, 17, and 15 persons were randomly assigned to full immersion, semi-immersion, and control groups. The subjects who were assigned to the full immersion group and semi-immersion group received virtual reality training for 6 weeks at 20 min at a time, 3 times per week. The control group received no intervention. Balance ability was evaluated by measuring the stability limit and the tandem walking test before and after the intervention. Results: Results showed significant differences among the three groups in the limit of stability of all directions and the tandem walking test after the intervention. The results of the limit of stability showed a significantly higher value in the full-immersion group than in the control group, and the results of the tandem walking test showed a significantly lower value in the full-immersion and semi-immersion groups than in the control group. Conclusion: The results indicate that the head-mounted display equipment for applying full-immersion virtual training is the most effective in enhancing the balance ability of the elderly.