• 한국수산과학회지
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• 제23권3호
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• pp.198-207
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• 1990

하천과 연안의 극심한 오염을 유발하고 있는 액상폐기물을 동해남부해역에 투기할 목적으로 용존산소분포에 기초하여 허용농도와 최적투기율을 결정하였다. 허용농도 산출은 Streeter-Phelps 모델을 이용하였으며 이 모델의 인자인 탈산소계수는 2개월 간격으로 1년동안 각 수심별 해수에 유기물을 주입한 후 산소소모양을 측정하여 Thomas slope method에 따라 구하였고, 재폭기계수는 Redfield의 폐쇄계모델을 적용, 1년간의 현장관측재료와 C. S. K 자료를 이용하여 산출하였다. 투기율은 Csanady의 초기희석 이론을 적용하였다. 연구결과 표층에서 각 수심까지의 탈산소계수는 하계 $0.24\~0.29/day$, 동계 $0.17\~0.20/day$였으며, 재폭기계수는 하계 $0.03\~0.39/day$, 동계 $0.04\~0.56/day$이었다. 이들 인자로써 초기희석수괴의 용존산소를 $5mg/{\iota}$ 이상으로 유지할 수 있는 각 수심까지의 허용농도는 하계 $2.83\~7.33mgBOD/\iota$, 동계 $4.37\~18.83mgBOD/\iota$이었다. 혼합수심(H)과의 관계를 이용하여 산출된 허용농도($mgBOD/\iota$)는 하계 $17.23\times(H)^{-0.37}$, 동계 $54.96\times(H)^{-0.62}$으로 표현할 수 있었다. 이 허용농도에 기초하여 최적투기율($m^3/sec$)은 이호의 폭(b, m), 흘수(h, m) 그리고 폐기물의 BOD($L_n$, $mg/\iota$)의 함수로 하계에는 $R=275{\times}bh^{0.63}/L_n$, 동계에는 $=745{\times}bh^{0.48}L_n$으로 산출되었다. 이러한 차리는 하계와 동계의 용존산소농도 분포와 이를 좌우하는 각 인자에 기인한 것이다.

• 환경위생공학
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• 제14권4호
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• pp.77-84
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• 1999

Most river quality problems are generated by pollutants which are discharged into the river as a consequence of human activities. And eutrophication occurs when water is over enriched with nutrients, principally nitrate and phosphate. Both these nutrients are found in many waste products, especially sewage even when the waste is treated. Eutrophication is concerned in lakes, but it also causes problems in river. Wide growth of Phytoplankton in rivers, leads to blockage of channels, but the main concern is deoxygenation because of the increase in plant life's demand for oxygen in revers. Fish, plant and animals die due to lack of oxygen. The increase of algae floating on the tops of water looks ugly and has attracted public attention and concern in recent years. One way of controlling eutrophication is to restrict the amount of waste carrying nitrate or phosphate from entering the water in the first place. another way is to remove it from the water after it has been entered. This study was carried out to investigate on the trophic state, nutrients and Chlorophyll-a concentration in the Han River. The results were as follows:1. Concentrations of total nitrogen were 2.208~9.221(5.133)mg/$\ell$2. Concentrations of total phosphate were 0.045~0.614(0.195)mg/$\ell$3. Chlorophyll-a concentration were $0.0-25.3(9.6)mg/m^3$.4. The correlation coefficient between T-P and Chlorophyll-a concentration was r=-0.856 at Sungsan sampling site.5. The correlation coefficient was r=-0.578~-0.767, between Paldang Dam outflow and Chlorophyll-a concentration at all sampling sites.

• 한국물환경학회지
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• 제28권2호
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• pp.178-184
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• 2012

BOD decay rate is a key parameter of BOD-DO models in streams and lakes. In the calibration of water quality modeling appropriate range of coefficient is required for guidance of parameter selection. In this study BOD decay rate was measured at 48 stream sites and 10 reservoir sites in 8 different river systems. The decay rate ranged from 0.09 to 0.25 $day^{-1}$ with a mean of 0.16 $day^{-1}$. Among river systems the decay rates showed significantly different ranges, with the Han River system showing higher values than other river systems. In comparing different types of water bodies, the decay rate was slightly higher in tributaries than in reservoirs and mainstreams. Our results can provide guidance to the selection of proper coefficient for various water bodies in the calibration of water quality models.

• 대한화학회지
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• 제26권5호
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• pp.340-348
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• 1982

술폭시화물을 보란으로 환원할 때 붕산트리페닐을 촉매량(10몰 퍼센트) 가하면 대응하는 황화물로 환원이 현저히 촉진됨이 관찰되어 이 환원계에 의해 구조적으로 서로 다른 몇가지 술폭시화물의 환원반응이 조사되었다. 술폭시화 테트라메틸렌은 5분 이내(보란만으로는 24시간 걸림) 술폭시화 디에틸, 술폭시화 디벤질, 술폭시화 벤질페닐은 1시간내에 정량적으로 환원이 완결되었으며 술폭시화 디페닐은 반응이 느려서 24시간에 90% 수율(보란만으로는 24시간에 18% 수율)로 환원되었다. 삼플루오르화붕소 에틸에테르 및 붕산트리에틸의 촉매효과는 붕산트리페닐보다 덜하였다.

• 대한화학회지
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• 제41권3호
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• pp.150-156
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• 1997

Bulgecinine의 선구물질인 (4S,5R)-1-acetyl-2-formyl-5-benzyloxymethyl-4-pyrrolidinol (15)을 diacetone-D-glucose로부터 합성하였다. Barton 탈산소화 반응, C-5에서의 반전, $-N_3$ 도입과 환원 및 C-2에서의 고리 형성을 통해 bulgecinine의 핵심 중간체인 두 고리 화합물 (6R)-6-Ο-benzyloxymethyl-(3R)-3-methoxy-2-oxa-5-azabicyclo-[2,2,1]heptane (13)을 합성하였다. 화합물 13을 N-아세틸화 후 산가수분해하여 얻은 bulgecinine 선구물질은 토토머화가 수반되어 (2S,4S,5R)-pyrrolidinol 유도체 15와 함께 (2S,4S,5R)-부분 입체 이성질체도 얻어졌다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.571-574
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• 1997

fMRI, functional MRI introduced recently appears based on the gradient echo technique which is sensitive to the field inhomogeneity developed due to the local susceptibility changes of blood oxygenation and deoxygenation. Common to all the gradient echo techniques is that the signal due to the susceptibility effects is generally decreased with increasing inhomogeneity due to the $T2^*$ effect or conventionally known as blood oxygenation level dependent (BOLD) effect. It is, also found that the BOLD sensitivity is also dependent on the imaging modes, namely whether the imaging is in axial, or coronal or sagittal mode as well as the directions of the vessels against the main magnetic field. We have, therefore, launched a systematic study of imaging mode dependent signal change or BOLD sensitivity as well as the signal changes due to the tilting angle of the imaging planes. Study has been made or both TRFGE sequence and CGE sequence to compare the distinctions of the each mode since each technique has different sensitivity against susceptibility effect. Method of computation and both the computer simulations and their corresponding experimental results are presented.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3269-3273
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• 2013

Graphene oxide (GO) has been of particular interest because it provides unique properties due to its high surface area, chemical functionality and ease of mass production. GO is produced by chemical exfoliation of graphite and is decorated with oxygen-containing groups such as phenol hydroxyl, epoxide groups and ionizable carboxylic acid groups. Due to the presence of those functional groups, GO can be utilized as a novel platform for hybrid nanocomposites in chemical synthetic approaches. In this work, GO-$SnO_2$ nanocomposites have been prepared through the spontaneous formation of molecular hybrids. When $SnO_2$ precursor solution and GO suspension were simply mixed, $Sn^{2+}$ was spontaneously formed into $SnO_2$ nanoparticles upon the deoxygenation of GO. Through further chemical reduction by adding hydrazine, reduced GO-$SnO_2$ hybrid was finally created. Our investigation for the electrocapacitive properties of hybrid electrode showed the enhanced performance (389 F/g), compared with rGO-only electrode (241 F/g). Our approach offers a scalable, robust synthetic route to prepare graphene-based nanocomposites for supercapacitor electrode via spontaneous hybridization.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2399-2402
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• 2013

The catalytic pyrolysis of cellulose was carried out over SAPO-11 for the first time. Pyrolyzer-gas chromatography/mass spectroscopy was used for the in-situ analysis of the pyrolysis products. The acid sites of SAPO-11 converted most levoglucosan produced from the non-catalytic pyrolysis of cellulose to furans. In particular, the selectivity toward light furans, such as furfural, furan and 2-methyl furan, was high. When the catalyst/cellulose ratio was increased from 1/1 to 3/1 and 5/1, the increase in the quantity of acid sites led to the promotion of deoxygenation and the resultant increase of the contents of light furan compounds. Because furans can be used as basic feedstock materials, the augmentation of the economical value of bio-oil through the catalytic upgrading over SAPO-11 is considerable.

• Investigative Magnetic Resonance Imaging
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• 제1권1호
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• pp.66-74
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• 1997

혈액의 산소화와 불 산소화에 따른 국부적인 자화율 효과의 변화에 의한 자장의 불 균일성에 민감한 경사 자장 에코 기법은 현재의 뇌기능 MR 영상의 기본이 되고 있다. 일반적으로 이러한 경사 자장 에코기법은 $T2^{*}$ 혹은 BOLD효과에 의한 자장의 불 균일성의 증가가 신호의 감소로 나타난다. BOLD 효과는 주자장에 대한 핏줄의 방향이나 영상 형식, 즉, 횡단면, 관상면, 또는 시상면에 따라 달라진다. 그래서 영상 형식과 영상면에 대한 기울임 각에 따른 신호의 변화와 BOLD 효과의 변화에 대한 정량적인 연구를 하였다. 연구는 자화율 효과에 대해 다른 민감도를 가지는 TRFGE 와 CGE 기법으로 이루어졌다. 컴퓨터 모의 실험과 실험 결과를 본 논문에 나타내었다.

• 한국물환경학회지
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• 제21권5호
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• pp.511-515
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• 2005

CBOD(carbonaceous BOD) decay rate was investigated for the execution of water quality model in Nakdong-Rive basin. Estimation of laboratory-derived CBOD decay rate, $k_l$ and CBOD decay rate in natural waters, $k_d$ were carried out. Hydraulic factors were applied for the calculation of $k_d$. Values of biochemical oxygen demand were investigated in Weagwan, Koreong, Jeokpo, Namgi and Mulgeom sites for the four times. The ranges of $k_l$ value were $0.04{\pm}0.01{\sim}0.14{\pm}0.03$. The values of $k_l$ in upstream sites were much larger than those in the downstream sites. The values of $k_d$ were 0.025, 0.036, 0.005 and 0.001 at Weagwan, Jeokpo, Namgi and Mulgeom, respectively, indicating that values of $k_d$ were generally larger than those of $k_l$.