• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
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• pp.87-91
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• 2008

The study examined fire resistance of concrete followed by change of mixed rate in PP and NY composite fiber and the results were as follows. In the event of fluidity in concrete not set, plane satisfied 600±100, its target slump flow, and fluidity was reduced as organic fiber's mixed rate was increased. Air amount satisfied 3.0±1.0, its target air amount, and didn't have distinct differences in reduction and increase according to organic fiber's kind and change of its mixed rate. However, it had a tendency that fluidity was reduced as the mixed rate was increased. In characteristics of hardening concrete, the 28th day compressive strength followed by organic fiber's kind and change of its mixed rate didn't have a lot of differences and satisfied high strength scope as about 70MPa. In spalling characteristics after fire resistance test, spalling was happened in non-mixture, plane combination, and P1N0. In other combinations, spalling resistance was happened. The relic compressive strength rate was 56%, the best condition, in P3N1(PP0.03%, NY0.01% compositeness) mixing PP fiber with NY fiber at once.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.145-149
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• 2000

We performed the geotechnical experiments of the hydraulic conductivity and compressive strength test with the stabilized soil in the laboratory, proved that it is useful to use the stabilized soil as an alternative for natural clay soil. Also, for mixing adding materials in the stabilized soil, it was determined that 1) the optimal mixing ratio of cement : bentonite : stabilizing agent was 90:60:1 of mass ratio(kg) for 1㎥ with soil, 2) it was also possible to use low quality bentonite(B\circled2) classified by swelling grade because of little difference from results of the hydraulic conductivity and compressive strength test with high quality bentonite(B\circled1). According to the results of the fixation ability of heavy metals(Pb$^{2+}$, Cu$^{2+}$, Cd$^{2+}$, Zn$^{2+}$) with soil and additives, authors can conclude that the higher pH condition had the more removal efficiency of heavy metals. B\circled1 and cement had especially high removal efficiency of heavy metals in a whole pH because of high alkalinity.alinity.

• 한국분말재료학회지
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• 제2권3호
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• pp.238-246
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• 1995

The purpose of this study is to establish powder metallurgy (P/M) fabrication processes for high performance 2XXX Al composites reinforced with SiC whiskers. Rapidly solidified 2XXX Al powders produced by commercial atomization technique were mixed with SiC whiskers. The results of mixing processes indicated that fluidized zone mixing technique was considerably effective for the large scale production of the mixture of Al powders and whiskers. In order to consolidate these $Al-SiC_w$ mixtures into $Al-SiC_w$ composite billets, a vacuum hot press was set up, and hot processing variables were investigated. Using the hot pressing temperature of $620^{\circ}C$ under the pressure of 50 MPa, good quality $Al-SiC_w$ composite billets having relatively homogeneous microstructure and sound Al/sic interfacial bonding were obtained. Composite billets were then extruded to bars having relatively homogeneous microstructures at the extrusion temperature of 450~500$^{\circ}C$ under the extrusion pressure of 700~ 1000 MPa. Mechanical properties of the extruded bars were found to be comparable with those of the composite processed by Advanced Composite Materials Corp. To improve mechanical properties of the composites, elimination of coarse intermetallic compounds, uniform distribution of reinforcements, and minimization of whisker breakage are suggested.

• 한국식품조리과학회지
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• 제24권4호
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• pp.473-479
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• 2008

The principal objective of this study was to evaluate the sensory properties and physical characteristics of muffins produced using different fats(butter, grape seed oil) and mixing methods(Creaming method, Foam method, Single-stage method). The muffins weighed between $63.25{\sim}64.50$ g and were $5.77{\sim}6.42$ cm in height. In a texture analyzer test, muffins prepared via the single-stage method with butter evidenced the highest hardness, gumminess, and chewiness values among the five kinds of muffin prepared in these experiments. The springiness value was highest in the muffin prepared via the foam method with grape seed oil. In the sensory evaluation, we detected no significant differences among the muffins in terms of flavor($4.76{\sim}5.24$), taste($4.65{\sim}5.29$), softness ($4.65{\sim}5.41$), and overall acceptability ($4.47{\sim}5.29$). In the chemical composition analysis, moisture and crude protein contents were found to be higher in the control group(p<0.05) than in the muffin prepared via the foam method with grape seed oil(p<0.01). We noted no significant differences among the muffins in terms of crude lipids or crude ash content.

• 대한영양사협회학술지
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• 제12권1호
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• pp.32-43
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• 2006

The purpose of this study is to find out the optimal mixing ratios of three different amounts of pectin, sugar and citric acid for preparation of garlic jam through response surface methodology(RSM) based on the sweetness, pH, color, sensory and texture test. As the sucrose content increased, the sweetness, cohesiveness, color, flavor, gloss and overall palatability of garlic jam tended to be high and the lightness tended to be low. As the pectin content increased, the adhesiveness of garlic jam tended to increase. As the citric acid content increased, the overall palatability of garlic jam tended to be high and the pH tended to be low. The Pectin levels were included 1.8-2.1g, sucrose levels were included 325-342g and citric acid levels were 5.8-6.1g. The optimal mixing ratios of a pectin, sugar and citric acid for manufacturing the best quality of garlic jam were 2.0g, 334g and 6.0g, respectively.

• 대한소아치과학회지
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• 제40권3호
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• pp.168-176
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• 2013

본 연구는 자이오머의 산성용액에서 시간에 따른 산중화능을 평가하고, 산에 노출된 자이오머의 표면변화를 관찰하기 위해서 시행되었다. 실험군으로는 수복용 자이오머인 Beautifil II와 유동성 자이오머인 Beautifil Flow F02, 대조군으로 수복용 복합레진인 $Filtek^{TM}$ Z250을 선택하였고, 원판과 가루 형태로 시편을 제작하여 pH 2.0의 염산 수용액과 혼합한 후 pH 값을 측정하였으며, 분말 형태의 자이오머는 새로운 염산 용액과 재혼합 후 pH 값을 측정하였다. 또한 주사전자현미경을 이용하여 원판형태 시편의 표면구조의 변화를 관찰하여 다음과 같은 결과를 얻었다. 원판 형태의 실험에서는 수복용 자이오머만이 실험 24시간 이후 유의한 pH 값의 증가를 보였다. 반면, 분말 형태의 실험에서는 수복용, 유동성 자이오머 모두 초기부터 유의한 수준의 pH 증가가 보였으며, 수복용 자이오머가 더 높은 pH 증가를 보였다. 분말 형태의 자이오머는 새로운 염산용액에서 이전 실험에 비해 낮은 정도의 pH 증가를 보였다. 또한, 충전용 자이오머의 표면에서 레진과 유동성 자이오머에 비해 더 많은 부식성의 구조적 변화가 발생했다. 결론적으로, 자이오머는 산중화능을 가지며, 필러 함량이 높은 충전용 자이오머는 유동성 자이오머보다 더 큰 산중화능이 있음을 알 수 있었다.

• 한국전자파학회논문지
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• 제20권8호
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• pp.770-776
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• 2009

본 논문에서는 일반적인 six-port 수신기의 한 구성 성분인 BPSK 수신기와 반사형 위상 천이기를 이용하여 QPSK 신호를 복조하는 방법을 제안, 검증하고자 한다. 기존의 일반적인 곱셈 혼합 방식이나 덧셈 혼합 방식의 I/Q 복조기는 혼합기부터 parallel-to-serial 변환기까지 I/Q 경로가 분리되어 있다. 본 논문에서는 I/Q baseband 신호 경로의 분리가 없는 새로운 I/Q 복조기를 제안한다. 이는 일반적인 수신기에 비하여 baseband 경로의 회로 크기와 전력 소모를 반으로 줄일 수 있는 장점이 있다. 또한, 데이터 복조 후 parallel-to-serial 변환기가 사용될 필요가 없다. 설계된 복조기 모듈은 L-band 반송파 주파수의 데이터 율 20 Mbps까지의 QPSK 변조 신호를 성공적으로 복조하였다.

• 한국대기환경학회지
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• 제29권6호
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• pp.780-788
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• 2013

This study attempted to determine important meteorological parameters related to airborne pollen concentrations in urban areas. Hourly pollen measurement data were prepared from a regular sampling with a volumetric Burkard spore trap at a site in the Ulsan city, during the spring season (March~May) of 2011. Results showed that the daily mean and maximum concentrations for total pollen counts during the spring season were statistically significantly correlated with both air temperature and wind speed; daily mean pollen concentration was the most highly related to daily maximum temperature (r=0.567, p<0.001). It was also identified that pollen concentration has a stronger relationship with wind speed at the rural site than at the urban one, which confirms that strong wind conditions over the pollen sources area can be favorable for pollen dispersal, resulting in increases in airborne pollen concentrations downwind. From the results of an oak-pollen episode analysis, it was found that there was a significant relationship between hourly variation of oak pollen concentrations and dynamic meteorological factors, such as wind and mixing height (representing the boundary layer depth); especially, a strong southwestern wind and elevated mixing height was associated with high nocturnal concentrations of oak pollen. This study suggests that temperature, wind, and mixing height can be important considerations in explaining the pollen concentration variations. Additional examination of complex interactions of multiple meteorological parameters affecting pollen behavior should be carried out in order to better understand and predict the temporal and spatial pollen distribution in urban areas.

• 동력기계공학회지
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• 제18권1호
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• pp.69-75
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• 2014

The pressure and temperature characteristics of mixed refrigerant gases in bulb for thermostatic expansion valve were studied using R22 refrigerant and $N_2$ gases. The characteristics of mixed refrigerant gases were investigated according to pressure variation and the variation of composition ratio of R22 refrigerant and $N_2$ gases in the temperature range of -$15^{\circ}C$~$15^{\circ}C$. The Maximum operating pressure(MOP) of mixed refrigerant gases were showed a tendency to decrease with decreasing the mixing ratio of $N_2$ gas. The characteristics in the case of the mixing ratio of 90:1 for R22 refrigerant and $N_2$ gases were the same result as Reference refrigerant. In addition, the characteristics of the mixed refrigerant gases in the mixing ratio of 90:1 for R22 refrigerant and $N_2$ gases were showed almost linear in the measurement range of pressure-temperature, and the physical properties also were showed similar results with Reference refrigerant. It was able to confirm that a MOP on the thermostatic expansion valve for sensing bulb can be maintained by adjusting the mixing ratio of R22 refrigerant and $N_2$ gases.

• Tribology and Lubricants
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• 제6권1호
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• pp.36-51
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• 1990

A parametric study of the thermal effects of a half-circumferential grooved journal bearings under aligned and misaligned conditions has been carried out by solving numerically the coupled Reynolds and energy equation system. Five different sets of boundary conditions for the energy equation have been used which include mixing between recirculating oil and inlet oil and a contraction ratio for the cavitation region. The effects of changes of the inlet oil temperature and pressure, the wall temperature and the L/D ratio have also been examined. For the range of parameters found in internal combustion engines, the mixing effectiveness at the groove and the resulting final mixture temperature have been found to be as important as the wall temperature and the heat transfer rate. The variability of the temperature, though, has been shown to smooth out the peaks of both pressure and friction during misaligned condition Distributions of friction and pressure in the oil are also examined which may be useful in attempts to reduce friction without reducing load. Results for an axial grooved bearing are also presentsed for comparision purpose.