• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.163-168
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• 2002

Through the developing measuring system of gas diffusivity, the experiments on carbon dioxide diffusivity in concrete carry out. From this, some important results was achieved. First, the times of reaching the steady state condition don't depend on the water/cement ratio with linearity. But, for the 0.42 w/c ratio the duration of the non-steady state condition is long. Second, in constant relative humidity, the diffusion coefficient shows linearity for the w/c ratio. Third, for the same w/c ratio, the influence of relative humidity on the diffusivity is very large. This shows the importance of the environmental condition for the carbonation. This study on $CO_2$ diffusivity in concrete is the first attempt within a country and will be important data.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.262-262
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• 2006

Biodegradable and amphiphilic di-block and tri-block copolymers, prepared with monomethoxy poly ethylene glycol (MPEG) and ${\varepsilon}-caprolactone\;({\varepsilon}-CL)$, were used for the application of W1/O/W2 multi- emulsion capsules. The effects of topology and the ratio of hydrophilic moiety of PCL-based polymers on the encapsulation efficiency of the $W_{1}/O/W_{2}$ multi-emulsion capsules containing Ascorbic Acid-2-Glucoside (AA-2-G) were investigated. The ratio of PEG and PCL was 1:0.5, 1:0.75, 1:1, and 1:1.25. PEG-PCL block copolymers were added to the first step of the preparation of $W_{1}/O$ emulsions. The dispersion stability, the particle size, the morphology of the $W_{1}/O/W_{2}$ multi-emulsion capsules were observed using an on-line turbidity meter, dynamic light scattering (DLS), a confocal microscopy (with FITC) and an optical microscopy. Biodegradable behavior of the PEG-PCL block copolymers and release behavior of AA-2-G were also observed by Gel Permeation Chromatography (GPC) and High Performance Liquid Chromatography (HPLC).

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.157-160
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• 1998

KS F 4419, which is dealt with the Inter-Locking block, states that water to cement ratio for manufacturing inter-locking block should be less than 25% and in KS F4419, the use of admixture is shown to be reluctant to recommend. In this paper, reinvestigation of some regulations in KS F 4419 are carried out. According to the experimental results, as W/C increases, flexural strength and compressive strength are tended to decrease, whereas they increases within certain range, Flexural strength and compressive strength have higher values in 1:2(W/C=35%), 1:4(W/C=45%) and 1:6(W/C=55%) of mix proportions. Moreover they have rather higher values with the containment of high range AE water-reducing agent. The absorption ratios decrease with the increase of W/C and the containment of high range AE water-reducing agent. Therefore, the regulations on the W/C and admixture in KS F 4419 reguire revision.

• 한국통신학회논문지
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• 제23권9A호
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• pp.2153-2164
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• 1998

This paper has presented the parameters for the coexistence between two systems in macro/microcell ovelaid W-CDMA WLL (wideband CDMA wireless local loop) and has calculated the capacity of forward/reverse link in microcell. To produce the capacity for analyzing system interference effects, we have shown tables and graphs with the parameters sucyh as RF channel bandwidth of WLL(W), the transmission rate of service message(R), the required signal power to noise power ratio( $E_{b/}$ $N_{0}$) for achieving accepatable error rate, te user number ( $N_{W1}$, $N_{W2}$) of the neighboring system, the signal power to interference power ratio(.GAMMA.$_{C1B}$, .GAMMA.$_{C2B}$) of the neighboring system, the normalized distance(d) between microcell and macrocell base-station, and microcell to macrocell radius ratio ( $R_{d}$). From the results, we have convinced that the capacity of microcell diminishes as increasing the user number ( $N_{W2}$) in macrocell, increasing the microcell radius, and decreasing the normalized distance(d) between microcell and macrocell base-station. Especially, we have known that when $R_{d}$=0.1, $N_{W2}$ must be below 24 at .GAMMA.$_{C2B}$ = 0 dB and below 8 at .GAMMA.$_{C2B}$ = 4 dB for the acceptable capacity raito to be over 80%. Therfore, this paper is usefult to design microcell W-CDMA WLL for accommodating more user number under the interference effects of macrocell W-CDMA WLL and is expected to be reference in power control if base-station.ation.ion.ation.ation.

• Journal of Biosystems Engineering
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• 제26권5호
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• pp.469-474
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• 2001

Milling the rice with low moisture requires more energy, produces more cracked rice, and results in reducing taste of cooked rice. Accordingly, it is necessary to add moisture to the rice with low moisture to obtain optimum moisture level for milling and taste of rice. This study was performed to evaluate the influence of initial moisture content and absorption rate on rice crack, milling energy and whiteness of milled rice and to obtain the information for design of rewetting system mounted on stirring device in grain bin. The tests were conducted for the four levels of initial moisture content in the range of 11.4 to 14.5%(w.b.) and six levels of absorption rate in the range of 0.04 to 1.0%, w.b./hr. In the case of lower moisture content below 12%(w.b.), crack ratios of brown rice were remarkably high regardless of initial moisture contents. Therefore, it was found that rough rice below 12%(w.b.) in initial moisture content could not rewetted by spraying water without crack generation of low level. Absorption rate must be below 0.3%, w.b./hr to maintain crack ratio increase of less than 1% regardless of initial moisture contents. In the case of allowable crack ratio increase of 2% and 5%, it was found that the maximum absorprion rate was respectively 0.6%, w.b./hr and 1.0%, w.b./hr in the initial moisture content of above 13.5%(w.b.). Rewetting the rough rice in moisture content of 11.4 to 14.5%(w.b.) to 14.3 to 16.9%(w.b.) decreased milling energy consumption by 15.9 to 22.3%. The effect of energy saving was higher in the samples of higher initial moisture content. Whiteness of milled rice was decreased by 0.5 to 1.5.

• 한국안전학회지
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• 제14권1호
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• pp.124-128
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• 1999

Product background of cement, sand and coarse aggregate differ from country to country, so that thermal behaviour of concrete make a difference in high temperature. To cope with demand, this paper is a study on compressive strength for W/C 45%, 55% and 65% by using domestic portland cement, Han-river sand, sea sand and crushed-coarse aggregate. As a result, it is shown that it is estimating to the mechanical properties of heated concrete specimens under various W/C ratio.

• 한국재료학회지
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• 제3권6호
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• pp.661-667
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• 1993

Conatact barrier metal용 selective W CVD 기술에서 $SiH_4//WF_6$(=R)유량비가 W막의 비저항, contact resistance, 접합주설전류 등의 전기적 특성에 미치는 영향을 $\beta$-W 의 생성에 촛점을 맞추어 조사하였다. R의 증가에 따라 W의 비저항이 증가하는데, 그 주원인은 $\alpha$-W로 부터 $\beta$-W 로의 상변태에 있다. $SiH_{4}$환원에 의한 CVD W에서 생성되는 $\beta$-W 는 산소에 의해서가 아니라 막내에 유입된 Si에 의하여 안정화된다. Si기탄상에 W를 증착할 때에는 R값이 클 경우에 $\beta$-W 가 생성되지만, TiN 기판상에 W를 증착할 때에는 R값이 큰 경우에도 $\beta$-W 가 생성되지 않는 것으로 나타났다. 또한 R이 증가함에 따라 접합누설전류가 증가하는데, 이것은 W-Si계면에 대한 수직방향으로의 Si의 소모뿐만 아니라 수평방향으로의 Si의 소모에도 그 원인이 있는 것으로 보인다.

• 한국식품저장유통학회지
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• 제14권4호
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• pp.364-368
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• 2007

가공이나 저장 중 쉽게 산화되는 특성을 갖는 비타민 C의 안정성과 가공적성을 향상시키고자 Zein-DP와 HPMC-FCC를 코팅제로 한 유동층 코팅법을 이용하여 코팅한 비타민 C 분말의 품질 특성에 대하여 조사하였다. 유동층 코팅은 비타민 C의 입자크기($80{\sim}100\;mesh,\;100{\sim}140\;mesh$)와 코팅액의 혼합비(1:1.6, 1:2.5, 1:3(w/w))를 달리하여 실시하였다. 코팅효율은 $80{\sim}100\;mesh$의 경우가 $100{\sim}140\;mesh$보다 높았고 코팅액의 혼합량이 많을수록 감소함을 보였다. 코팅된 필름의 두께는 $80{\sim}100\;mesh$의 경우가 $100{\sim}140\;mesh$보다 두꺼웠으며, 코팅된 입자의 입도분포도는 코팅액 혼합비 1:3에서 가장 좁았다. 코팅분말의 DPPH 소거능은 코팅 전 입자크기와 코팅액 혼합비에 따른 큰 차이를 보이지 않았다. 상기의 코팅된 분말의 품질 특성에 코팅물질의 종류는 거의 영향을 미치지 않았다. 이로써 비타민 C의 유동층 코팅에 적합한 조건으로 비타민 C의 입자크기는 $80{\sim}100\;mesh$, 비타민 C와 코팅 액의 혼합비는 1:3(w/w)으로 판단된다.

• 한국세라믹학회지
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• 제21권3호
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• pp.221-230
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• 1984

In this study an investigation was made to determine optimum ratio between $SO_3$, MgO and $K_2O$ that maximizes $C_2S$ formation in Clinkering reaction Using response surface analysis method. It was proved that 1) Residual $K_2O$ int he clinker should be converted to $K_2SO_4$ because $K_2SO_4$ has less effect on the burnability than $K_2O$, 2) Optimum ratio if $SO_3$/K2O is 1.5, 3) Optimun balance between $CaSO_4$ and MgO is to be adjusted to such a level that w/o SO3=0.7(w/o MgO-2).4) In case of lack of $K_2O$ free CaO was minimized when $K_2SO_4$=2.3w/o and MgO=1.5w/o but if remaining $K_2O$ was 2w/o free CaI was minimized in the level that $K_2SO_4$=2.3w/o and MgO =1.5 w/o but if remaining $K_2O$ was 2 w/o free CaO was minimized in the level that $K_2SO_4$=4.5w/o and MgO =3.0 w/o.

• 한국식품영양과학회지
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• 제25권5호
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• pp.810-816
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• 1996

침지온도 $20^{\circ}C$에서 침지 후 30분에서 35분 사이에 대부분의 품종이 평형에 도달했으며, 평형수분 함량은 0.3247~0.3577(g $H_2O/g$ dry matter)로 나타났다. 초기 수분흡수 속도에서는 품종간에 차이를 나타내었으며, 특히 낙동벼의 경우 0.123g $H_2O$/$min^{1/2}$로 가장 높은 값을 나타냈다. 취반 후 밥의 수분 함량은 가수율에 따라 증가하였으며, 가수율이 1.3에서 1.6(v/w)으로 증가함에 따라서 밥의 수분 함량은 품종에 따라 약 6.0~7.0%증가하였다 가수율에 따른 취반 후 밥의 경도는 가수율이 증가할수록 감소하는 경향이었으며 끈기와 끈기대 경도의 비는 대체적으로 증가하였다.