• Economic and Environmental Geology
• /
• v.42 no.5
• /
• pp.509-512
• /
• 2009

Powder diffraction patterns of the zeolite mesolite ($Na_{5.33}Ca_{5.33}Al_{16}Si_{24}O_{80}{\cdot}21.33H_2O$), with a natrolite framework topology were measured as a function of pressure up to 5.0 GPa using a diamond-anvil cell and a $200{\mu}m$-focused monochromatic synchrotron X-ray. Under the hydrostatic conditions mediated by pore-penetrating alcohol and water mixture, the elastic behavior of mesolite is characterized by continuous volume expansion between ca. 0.5 and 1.5 GPa, which results from expansion in the ab-plane and contraction along the c-axis. Subsequent to this anomalous behavior, changes in the powder diffraction patterns suggest possible reentrant order-disorder transition. The ordered layers of sodium- and calcium-containing channels in a 1:2 ratio along the b-axis attribute to the $3b_{natrolite}$ cell below 1.5 GPa. When the volume expansion is completed above 1.5 GPa, such characteristic ordering reflections disappear and the $b_{natrolite}$ cell persists with marginal volume contraction up to ca. 2.5 GPa. Further increase in pressure leads to progressive volume contraction and appears to generate another set of superlattice reflections in the $3c_{natrolite}$ cell. This suggests that mesolite in the pressure-induced hydration state experiences order-disorder-order transition involving the motions of sodium and calcium cations either through cross-channel diffusion or within the respective channels.

• Economic and Environmental Geology
• /
• v.47 no.6
• /
• pp.635-643
• /
• 2014

Sustaiable development yield of groundwater in Korea has been determined according to 10 year drought frequency of groundwater recharge in the standard mid-sized watershed or relatively large area of district. Therefore, the evaluation of groundwater impact in a small watershed is hard to apply. Fot this purpose, a novel approach to estimate cell based sustainable development yield of groundwater (SDYG) is suggested and applied to Gyeongju region. Cell based groundwater recharge is computed using hydrological component analysis using the SWAT-MODFLOW which is an integrated surface water-groundwater model. To estimate the potential amount of groundwater development, the existing method which uses 10 year drought frequency rainfall multiplied by recharge coefficient is adopted. Cell based SDYGs are computed and summed for 143 sub-watersheds and administrative districts. When these SDYGs are combined with groundwater usage data, the groundwater usage rate (total usage / SDYG) shows wide local variations (7.1~108.8%) which are unseen when average rate (24%) is only evaluated. Also, it is expected that additional SDYGs in any small district could be estimated.

• Journal of Dairy Science and Biotechnology
• /
• v.21 no.2
• /
• pp.81-87
• /
• 2003

This study was conducted to correlate the quality depending upon sensory evaluation of ESL(extended shelf life) and non-ESL milk during the shelf life. The most important quality assurance is sensory evaluation for dairy products. ESL and non-ESL milk were stored at $5^{\circ}C$ and $10^{\circ}C$ for 14 days. In order to compare physicochemical and sensory properties, pH, TA(titratable acidity), protein, fat, lactose, FFA(free fatty acid), and other organoleptic characteristics were measured. The results showed that physicochemical properties were not significantly changed during storage. On the other hand, the freshness was affected by storage conditions. The most freshness depending upon sensory evaluation was monitored at 5 days storage. Descriptive and acceptability analysis showed that more acceptable milk was ESL milk than non-ESL milk because of off-flavor and after taste of non-ESL milk. According to these results, it was shown that the freshness of milk products depends on sensory. And ESL milk was fresher than non-ESL milk after storage.

• Korean Journal of Environmental Agriculture
• /
• v.30 no.4
• /
• pp.377-381
• /
• 2011

BACKGROUND: Ammonia emissions from field-applied livestock manure are considered a threat to the environment worldwide. In Korea, a large amount of liquid manure was applied in the rice field before rice transplanting in order to reduce chemical fertilizer use. This study was conducted to provide the optimal flooding time after liquid manure application in an attempt to minimize ammonia emission. METHODS AND RESULTS: Ammonia emission from paddy field applied with liquid pig manure following different flooding time was measured using the dynamic chamber method. The five treatments used were : application of liquid pig manure to paddy field in flooding condition (F0T); one day (F1T) and three days (F3T) after flooding; without flooding (NF), and flooding without the application of liquid pig manure (control). Among the treatment, the highest ammonia emission was observed in F0T. The cumulative ammonia emission of F1T and F3T for 12 days were very similar and were about 4.7 times less than that of the F0T treatment. CONCLUSIONS: Ammonia emission in paddy field could be significantly reduced by liquid pig manure application after flooding rather than application of liquid pig manure in flooding condition. Therefore, flooding after liquid pig manure application would provide much more nitrogen for rice growth due to the reduction of ammonia emission.

• Korean Journal of Environmental Agriculture
• /
• v.27 no.1
• /
• pp.72-79
• /
• 2008

Phytosociological study was carried out to investigate the structural characteristics of Humulus japonicus community in the Middle area of Korea. The vegetation data of total 67 $relev\acute{e}s$ were analyzed by the $Z\ddot{u}rich$-Montpellier school's method. Upper layer plant communities of Humulus japonicus were classified into four community groups : Humulus japonicus-Artemisia princeps community, Chenopodium album community, Setaria viridis-Echinochloa crus-galli community and Typical community. Lower layer plant communities were classified into five community groups : Galium spurium-Stellaria aquatica community, Equisetum arvense community, Persicaria theunbergii community, Echinochloa crus-galli-Digitaria ciliaris community and Typical community. According to the results of canonical correspondence analysis by vegetation and environmental factor, Setaria viridis-Echinochloa crus-galli community of upper layer was distributed throughout the soil with high relative light and soil hardness. Chenopodium album community appeared in the soil with high pH. Galium spurium-Stellaria aquatica community of lower layer was formed in the high soil pH. Persicaria theunbergii community and Echinochloa crus-galli-Digitaria ciliaris community were distributed in the soil with high moisture.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2002.02a
• /
• pp.558-563
• /
• 2002

시설원예에서 난방장치를 사용하는 겨울철 재배 농산물의 생산비 중 난방 연료비가 30%~37% 정도를 차지하여 비중이 가장 높다. 따라서 시설원예 농가에서는 난방비를 절감하는 것이 농가소득과 직결되므로, 난방장치의 선정이 대단히 중요하다. 본 연구에서는 겨울철 재배 농산물의 생산비 중 30%-37% 정도를 차지하는 연료비를 절감하기 위해 기존의 온풍난방기와 다른 새로운 방식의 열교환기와 원심식 송풍블로워를 사용하는 블로워 송풍방식의 온풍난방기를 개발하고 개발된 온풍난방기의 가동으로 인한 난방 연료비 절감효과와 온실내의 균일한 온도분포를 획득하기 위해 8연동 비닐온실에서의 시험을 실시하였으며 얻어진 결과를 요약하면 다음과 같다. 가. 저 정압용의 전동기 축직결식 송풍팬을 대신하여 고 정압용의 블로워 송풍팬을 장착하고 열교환 면적을 크게 한 지그재그식 환류의 열교환실을 채용한 온풍난방기를 개발하였다. 나. 공시한 온실에서 기존 온풍난방기의 2일 가동시 DH당 연료 사용량이 평균 1.082$\ell$/$^{\circ}C$.hr 이며, 블로워 송풍방식 온풍난방기의 3일 가동시 DH당 연료 사용량은 평균 0.854$\ell$/$^{\circ}C$.hr로써 21%의 난방 연료비 절감효과가 나타났다. 다. 블로워 송풍방식 온풍난방기는 동일시간대 3$^{\circ}C$의 경시적 온도변화가 발생하였고, 기존의 은풍난방기의 동일시간대 온도변화는 최대 6.1$^{\circ}C$로 나타나 개발된 블로워 송풍방식 온풍난방기가 동일시간대 온실내의 온도변화를 크게 줄일 수 있었고 온도분포를 비교적 균일하게 하는 효과가 있음을 확인하였다.도 33$^{\circ}C$를 기준으로 한 열 회수 시간은 유입공기 온도가 52$^{\circ}C$ 및 64$^{\circ}C$ 일 각각 120분 및 140분으로 나타났다. (3) 제 3종 자갈: 축열조로 공급되는 공기의 온도가 52$^{\circ}C$와 64$^{\circ}C$ 일 때, 축열조 출구의 공기온도가 33$^{\circ}C$에 도달될 때까지 가열되는데 소요된 시간은 가열공기의 온도가 52$^{\circ}C$와 64$^{\circ}C$ 일 때 각각 180분과 150분이었고, 방열에 소요된 시간은 각각 240분 및 270분으로 나타났다. 방열과정 동안 축열조 출구의 최고 공기온도는 가열 공급공기의 온도가 52$^{\circ}C$ 와 $65^{\circ}C$일 때 각각 35.5$^{\circ}C$ 및 39.5$^{\circ}C$였다. 출구 공기온도 33$^{\circ}C$이상을 기준으로 한 에너지 회수시간은 유입공기 온도가 52$^{\circ}C$ 및 64$^{\circ}C$일 때 각각 140분 및 160분으로 나타났다. 이와 같이 자갈이 작을수록 축열조 출구의 공기온도가 기준온도 33$^{\circ}C$에 도달되는 시간이 길었으며, 이것은 축열조내의 공극이 작고 비중량이 커 자갈층을 가열시키는 축열시간이 길어지기 때문인 것으로 사료된다. 또한 작은 자갈일수록 방열시간도 다소 길어져 회수 가능 열에너지가 큰 것으로 나타났다

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2002.02a
• /
• pp.564-572
• /
• 2002

본 연구에서는 크기가 서로 다른 자갈로 이루어진 3종류의 축열 매체에 대한 현열축열 특성을 조사하였으며, 그 연구 결과를 요약하면 다음과 같다. (1) 제 1 종 자갈: 축열조로 공급되는 공기의 온도가 5$0^{\circ}C$와 62$^{\circ}C$ 일 때, 축열조 출구의 공기온도가 33$^{\circ}C$에 도달될 때까지 가열되는 축열시간은 각각 170분과 130분이었으며, 방열시간은 각각 210분 및 250분으로 나타났다. 또한, 방열시 출열조 출구의 최고 공기 온도는 공급공기의 온도가 5$0^{\circ}C$와 62$^{\circ}C$ 일 때 각각 34.5$^{\circ}C$ 및 36.5$^{\circ}C$였으며, 출구 공기온도 33$^{\circ}C$이상을 기준으로 한 열 회수 시간은 각각 100분 및 115분으로 나타났다. (2) 제 2종 자갈: 축열조에 공급되는 공기의 온도가 52$^{\circ}C$와 64$^{\circ}C$ 일 때, 축열조 출구의 공기온도가 33$^{\circ}C$에 도달될 때까지 가열되는데 소요된 시간은 각각 175분과 140분이었고, 방열에 소요된 시간은 각각 215분 및 250분으로 나타났다. 방열과정 동안 축열조 출구의 최고 공기온도는 공급공기의 온도가 52$^{\circ}C$와 $65^{\circ}C$ 일 때 각각 35$^{\circ}C$ 및 38$^{\circ}C$였다. 축열조 출구의 공기온도 33$^{\circ}C$를 기준으로 한 열 회수 시간은 유입공기 온도가 52$^{\circ}C$ 및 64$^{\circ}C$ 일 각각 120분 및 140분으로 나타났다. (3) 제 3종 자갈: 축열조로 공급되는 공기의 온도가 52$^{\circ}C$와 64$^{\circ}C$ 일 때, 축열조 출구의 공기온도가 33$^{\circ}C$에 도달될 때까지 가열되는데 소요된 시간은 가열공기의 온도가 52$^{\circ}C$와 64$^{\circ}C$ 일 때 각각 180분과 150분이었고, 방열에 소요된 시간은 각각 240분 및 270분으로 나타났다. 방열과정 동안 축열조 출구의 최고 공기온도는 가열 공급공기의 온도가 52$^{\circ}C$ 와 $65^{\circ}C$일 때 각각 35.5$^{\circ}C$ 및 39.5$^{\circ}C$였다. 출구 공기온도 33$^{\circ}C$이상을 기준으로 한 에너지 회수시간은 유입공기 온도가 52$^{\circ}C$ 및 64$^{\circ}C$일 때 각각 140분 및 160분으로 나타났다. 이와 같이 자갈이 작을수록 축열조 출구의 공기온도가 기준온도 33$^{\circ}C$에 도달되는 시간이 길었으며, 이것은 축열조내의 공극이 작고 비중량이 커 자갈층을 가열시키는 축열시간이 길어지기 때문인 것으로 사료된다. 또한 작은 자갈일수록 방열시간도 다소 길어져 회수 가능 열에너지가 큰 것으로 나타났다.

• Analytical Science and Technology
• /
• v.17 no.1
• /
• pp.69-81
• /
• 2004

The formation pattern of DBPs (disinfection by-products) in raw water treated with hypochlorite, chlorine disinfectant was studied. TOC (total organic carbon), residual chlorine, turbidity and 14 DBPs in raw water from Han-river and Nakdong river during 1 ~ 14 days were determined. Total DBPs in Han river was 101.3 ng/mL (789.6 nM) after 7days and THMs (trihalomethanes) are the dominant portion of 68%. HAAs (haloacetic acids) and chloral hydrate were determined 19% and 10% respectively. In Nakdong river total DBPs was 98.4 ng/mL (678.6 nM) and dominant class was HAAs. (55.8 ng/mL, 57%) THMs(34%) and N-compounds like HANs (haloacetonitriles, 5%) and chloropicrin were increased. It may be explained that high concentration of NH4-N in Nakdong river react with chlorine produced chloramine and this formed different pattern of DBPs. As a result, total DBPs formation pattern depends on raw water and disinfectant and in generally the initial concentration of acidic HAAs was high and THMs was increased gradually.

• Analytical Science and Technology
• /
• v.17 no.6
• /
• pp.481-488
• /
• 2004

Solvent extraction of Ni(II) into a chloroform by using salen[N,N'-Bis (salicylidene)-ethylenediamine] as a ligand has been studied. Salen was synthesized from ethylenediamine and salicylaldehyde by simple condensation reaction in an ethanol. Salen formed a 1 : 1 complex with Ni(II) and its extraction constant was $10^{5.12}$. For the determination of Ni(II) in sea water samples, some experimental conditions such as pH of solution, amount of salen, acid type and concentration for back extraction, extraction time, and influence of foreign ions were optimized by using a synthetic sea water. The sea water of which the composition was similar to a natural sea water was synthesized in this laboratory. Trace Ni(II) was extracted into the chloroform in the weak basic solution above pH 8. And the nickel could be quantitatively extracted with the concentration of salen higher than $1.2{\times}10^{-4}mol/L$. This concentration was more than 180 times of Ni(II) in the solution with a mole ratio. Real samples of Korean coastal sea water were analyzed under optimized conditions. Even though Ni(II) was not detected in these samples. Recoveries more than 98% were obtained in the samples which 40 ng/mL of Ni(II) was spiked. And detection limit of proposed method was 1.3 ng/mL. From these results, it could be known that salen of this type would be applied for the determination of trace metals as an organic chelating reagent.

• Analytical Science and Technology
• /
• v.17 no.1
• /
• pp.1-7
• /
• 2004

The synergistic solvent extraction of Mn(II) by N-nitroso-N-phenylhydroxylamineammonium salt (cupferron) and tetrabutylammonium ion ($TBA^+$) has been studied. In the presence of $TBA^+$, over 95% Mn(II) was extracted from an aqueous solution into chloroform by the cupferron in the pH range of 4 to 10. But a part of Mn(II) was extracted with only cupferron. The ternary complex of Mn(II) was more efficiently extracted into $CH_2Cl_2$ and $CHCl_3$ than other nonpolar solvents. The extracted Mn(II) was determined in the back-extracted $HNO_3$ solution by GF-AAS. This fixed procedure was applied to the determination of trace Mn(II) in tap water samples of pH 5.0. The detection limit equivalent to 3 times standard deviation of the background absorption was 0.37 ng/mL and Mn(II) was determined with the range of 0.4 to 1.01 ng/mL in our laboratory's tap water. And the recovery was 94 to 107% in samples in which 2.0 ng/mL Mn(II) was spiked. The interferences of common concomitant elements such as Cu(II), Ca(II), Fe(III) and so on were not shown up to $10{\sim}20{\mu}g/mL$. From these results, this procedure could be concluded to be applied for the determination of trace Mn(II) in other environmental water samples.