• 정보처리학회논문지D
• /
• 제9D권2호
• /
• pp.259-266
• /
• 2002

소프트웨어 개발시 중요하게 제기되는 문제점으로 소프트웨어 생명주기의 초기단계에서 개발에 투입될 노력과 비용을 추정하는 능력이다. 측정된 소프트웨어 규모인 기능점수 (FP, Function Point)로부터 프로젝트 개발에 소요되는 노력과 비용을 추정하는 회귀모델들이 제안되었다. 그러나 이들 제안된 모델들은 사용한 표본의 크기가 작고, 과거에 개발된 프로젝트를 대상으로 하고 있다. 1990년대에 개발된 789개 소프트웨어 개발 프로젝트들에 투입된 개발노력에 이들 모델을 적용한 결과 결정계수 $R^2$가 0.53 이하로 데이터의 변동을 설명하였다. 본 논문은 프로젝트 인도율(PDR)을 이용하여 동질성을 갖는 그룹으로 분류하여 개발노력을 추정하는 모델을 제안하였다. 제안된 모델은 랜덤한 잔차 분포를 갖고 있고, 대부분의 PDR 범위에서 0.99이상의 결정계수로 데이터의 변동을 설명하였다.

• KSBB Journal
• /
• 제27권2호
• /
• pp.91-96
• /
• 2012

In this study, a newly synthesized thiazolidinedione derivative, TD49 with a highly selective algicide to red tide, was examined in order to evaluate the bioconcentration on aquatic organisms of coast. BAF (accumulation of TD49 by aquatic food chain) and BCF (accumulation of TD49 by sea water) were examined employing the shrimp (Fenneropenaeus chinensis) as the feed organism, and the olive flounder Paralichthys olivaceus as a consumer in marine ecosystem. Bioconcentration degree in sea water showed that the order in P. olivaceus was viscera > gill > muscle. The average BCF values of TD49 were 67.70, 63.32 and 20.25 at viscera, gill and muscle, respectively. Bioaccumulation degree using feed showed that the order in the organs of P. olivaceus was viscera > gill > muscle. The average BAF values of TD49 were 175.89, 114.88 and 32.59 at viscera, gill and muscle, respectively. When compared with two results, the accumulation by the food and water was higher than that by water. After the elimination experiment in sea water, the TD49 concentration was 2.81 nmole/g in the viscera and were not found in the gill and the muscle. More than 50% of the accumulated TD49 were eliminated from viscera in 7 days and all the accumulated TD49 were eliminated from gill and muscle in 7 days. On the other hand, the octanol/water partition coefficient (log $K_{ow}$) was measured to be 3.66 and experimental BCF of this study was 67.7.

• Bulletin of the Korean Chemical Society
• /
• 제35권12호
• /
• pp.3637-3641
• /
• 2014

In this study, we analyzed the toxicity of mixtures of dimethylformamide (DMF) and methyl ethyl ketone (MEK) or DMF and toluene (TOL) and predicted their toxicity using quantitative structure-activity relationships (QSAR). A QSAR model for single substances and mixtures was analyzed using multiple linear regression (MLR) by taking into account the statistical parameters between the observed and predicted $EC_{50}$. After preprocessing, the best subsets of descriptors in the learning methods were determined using a 5-fold cross-validation method. Significant differences in physico-chemical properties such as boiling point (BP), specific gravity (SG), Reid vapor pressure (rVP), flash point (FP), low explosion limit (LEL), and octanol/water partition coefficient (Pow) were observed between the single substances and the mixtures. The $EC_{50}$ of the mixture of DMF and TOL was significantly lower than that of DMF. The mixture toxicity was directly related to the mixing ratio of TOL and MEK (MLR $EC_{50}$ equation = $1.76997-1.12249{\times}TOL+1.21045{\times}MEK$), as well as to SG, VP, and LEL (MLR equation $EC_{50}=15.44388-19.84549{\times}SG+0.05091{\times}VP+1.85846{\times}LEL$). These results show that QSAR-based models can be used to quantitatively predict the toxicity of mixtures used in manufacturing industries.

• Archives of Pharmacal Research
• /
• 제26권4호
• /
• pp.258-263
• /
• 2003

Colon-specific delivery of glucocorticoids is highly desirable for the efficient treatment of inflammatory bowel disease. We synthesized prednisolone 21-sulfate sodium (PDS) as a colon-specific prodrug of prednisolone (PD) and investigated its properties using rats as test animals. We expected that introduction of sulfate ester as a sodium salt might increase the hydrophilicity and restrict the absorption in the GI tract. If PDS is stable and nonabsorbable in the upper intestine, it will be delivered to the colon as an intact form, where it hydrolyze by the sulfatase to release PD. Compared with PD, the solubility of PDS increased and the apparent partition coefficient decreased greatly. PDS was stable on incubation with pH 1.2 and 6.8 buffer solutions and with the contents of the stomach and small intestine. On incubation with the cecal contents, PDS decreased to 9.6％ of the dose in 10 h producing PD. The amount of PD increased to give a maximum 54％ of the dose and decreased. As a control, when PD was incubated with the cecal contents, it decreased to 29％ of the dose in 8 h, which implied that reduction of PD proceeded under such conditions. These results suggested that hydrolysis of PDS took place to produce and accumulate PD, which decreased by reduction as the incubation period extended. Our results suggested that PDS can be a promising colon-specific prodrug of PD, and sulfate ester group might serve as a potential colon-specific promoiety, especially for the drugs which are resistant to reduction in the colon.

• 대한토목학회논문집
• /
• 제8권3호
• /
• pp.119-128
• /
• 1988

본 연구의 목적은 불포화 토양내 유기독성물질의 삼계평형분포에 미치는 함수율(0.3~1.255%)과 온도 ($4{\sim}40^{\circ}C$)의 영향을 정량화 하는데 있다. 본 실험에 사용한 토양은 한국토양의 주종을 이루고 있는 마사토이며, 유기독성물질로써는 Dichlolomethane과 1, 1, 1-Trichloloethane을 사용하였다. 토양내 수분이 분포하는 모양에 따른 두가지 가정(가정 1. 토양수분이 토양입자의 표면을 완전히 둘러싸고 있다. 가정 2. 부분적으로 둘러싸고 있다.)에 기초하여 구한 두 모델과 실험결과를 비교하였다. 이 실험의 결과 함수율이 증가함에 따라 $K_{eff}$ 값은 급격히 감소하는 것을 알았다. 또한 온도가 증가함에 따라 $K_{eff}$ 값은 감소하였는데, 함수율이 낮을수록 이러한 온도의 영향은 더욱 크게 나타났다. $K_{eff}$ 값은, 모델II를 이용하여 구한 예측치와 더 잘 일치하였다. 이 결과로부터 토양의 함수율이 매우 낮을 경우, 토양수분은 부분적으로 토양입자를 둘려싸고 있다는 가정이 타당함을 실험적으로 증명할 수 있게 되었다.

• 한국환경독성학회:학술대회논문집
• /
• 한국환경독성학회 2002년도 추계국제학술대회
• /
• pp.154-154
• /
• 2002

Benzoyl peroxide is a High Production Volume Chemical, which is produced about 1,375 tons/year in Korea as of 2001 survey. The substance is mainly used as initiators in polymerization, catalysts in the plastics industry, bleaching agents for flour and medication for acne vulgaris. The substance is one of seven chemicals of which human health and environmental risks are being assessed by National Institute of Environmental Research (NIER) under the frame of OECD SIDS Program. In this study, Quantitative Structure-Activity Relationships (QSAR) is used for getting adequate information on the physical-chemical property and the environmental fate of this chemical. For the assessment of benzoyl peroxide, models such as MPBPWIN for vapor pressure, KOWWIN for octanol/water partition coefficient, HENRYWIN for Henry's Law constant, AOPWIN for photolysis and BCFWN for bioconcentration factor (BCF) were used. These (Q)SAR model programmes were worked by using the SHILES (Simplified Molecular Input Line Entry System) notations. The physical-chemical properties and the environmental fate of benzoyl peroxide were estimated as followed : vapor pressure =0.00929 Pa, Log Kow = 3.43, Henry's Law constant = 0.00000354 atm-㎥/mole at 25 $^{\circ}C$, the half-life of photodegradation = 3 days, bioconcentration factor (BCF) = 92

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제10권3호
• /
• pp.9-15
• /
• 2005

토양/대수층 처리(Soil Aquifer Treatment, SAT)는 하수처리장으로부터의 2차 또는 3차 처리수를 대수층으로 침투시켜, 토양 매질에서 일어나는 물리적/생화학적 반응에 의해 재처리하는 용수 재이용 기술이다. SAT에서의 주요 관심 대상은 유기물과 질소화합물의 제거와 이송에 있다. 본 연구에서는 암모늄의 질산화 반응, 질소산회물의 탈질 반응, 그리고 유기물의 산화반응을 고려하여 SAT에서 일어나는 반응 메커니즘을 규명하고 이를 지하수 흐름과 이송 모렐 에 접목시킴으로써 SAT 모델링 시스템을 구현하고자 하였다. 실험실 일차원 불포화 토양 컬럼 실험을 통한 모델 검증에서 암모늄, 질산성 질소, DOC, 용존산소 모두 일정한 농도 범위 안에서 일치하였다. 모델 변수에 대한 민감도 분석에서, 암모늄 분배계수는 유출부의 암모늄 농도에, 용존산소 저해상수는 유출부의 유기물 농도에, 그리고 미생물 감쇄계수는 유출부의 용존산소 농도에 영향을 주었다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제9권1호
• /
• pp.28-38
• /
• 2004

본 연구는 지하수로부터 유래한 벤젠이 실내공기에 휘발되어 호흡을 통하여 인체에 유입될때 각 장기에 분포하고 제거되는 것을 묘사하는 동적약리학 모델의 불확실성 및 중요도 분석의 결과를 제공하였다. 오염된 실내공기의 호흡을 통해 체내에 유입된 벤젠이 각 장기에 분포하는 비율과 농도를 모의하기 위해 기존의 동적약리학 모델을 적용하였으며 간에서의 분해대사를 포함하여 구성하였다. 본 연구는 동적약리학 모델의 각 장기의 혈류량, 분배계수, 분해상수, 부피 등과 같은 인자들에 대한 지식 및 측정의 부족에서 오는 고정된 단일 값의 사용이 야기하는 불확실성 문제에 대해 초점을 맞추었다. 이를 해결하기 위해서 동적약리학 모델과 불확실성 분석을 동시에 수행되었으며 앞으로 휘발성 유기화합물과 관련한 위해도 평가에서의 이해를 높일 수 있다고 생각된다.

• 한국물환경학회지
• /
• 제20권5호
• /
• pp.512-519
• /
• 2004

Hybrid barriers using reduction and immobilization were tested to remediate the groundwater contaminated with multi-pollutants in this study. Iron filings and HDTMA(hexadecyltrimethylammonium)-bentonite were simulated in columns to assess the performance of hybrid barriers for remediation of trichloroethylene(TCE)-contaminated water. TCE reduction rate for the mixture of iron filings and HDTMA-bentonite was about 7 times higher than that for iron filings, only suggesting the reduction of TCE was accelerated when HDTMA-bentonite was mixed with iron filings. TCE reduction rate for the two layers of iron and HDTMA-bentonite was nearly similar to that for iron filings alone, but the partition coefficient($K_d$) for the two layers was 4.5 times higher than for that iron filings only. TCE was immobilized in the first layer with HDTMA-bentonite, and then dechlorinated in the second layer with iron filings. HDTMA-bentonite may contribute to the increase in TCE concentration on iron surface so that more TCE can be reduced. Also, TCE removal in the hybrid barriers was not affected by chromate and naphthalene while the reduction rate of TCE with the co-existing contaminants by iron filings was significantly decreased. Significant TCE removal in this research indicates that the proposed hybrid barrier system has the potential to become the effective remediation alternative during the occurrence of oil shock. Also, if subsurface environments are contaminated with multi-pollutants that contain non-reducible compounds as well as reducible compounds such as TCE, the conventional reactive barriers cannot be applied to this subsurface environment, while the proposed hybrid system can be applied successfully.

• Journal of Pharmaceutical Investigation
• /
• 제22권3호
• /
• pp.185-196
• /
• 1992

To assess its suitability as a prodrug of 5-fluorouracil (5-FU), 1-glycyloxymethyl-5-FU HCl (GFU), a 5-fluorouracil derivative having a glycyloxymethyl group at the N-l position was synthetized. Its physicochemical properties and hydrolysis kinetics, in aqueous solution of pH $1{\sim}10$ and in the presence of human plasma or rat liver homogenate were studied. Its acute toxicity and antitumor activity against sarcoma 180 were also examined, GFU showed higher lipid/water partition coefficient than 5-FU. The calculated $pK_{\alpha}$ values of 5-FU and GFU were 8.02 and 7,20, respectively. The decomposition rates of GFU in aqueous solution showed a pH-dependence over the pH range used, which could be ascribed to solvent catalysed hydrolysis reaction at pH lower than 4,16 and to specific hydroxide ion hydrolysis reaction at pH higher than 4,16, The half-life of GFU was 6,9 min in 80% human plasma solution and less than 3 min in rat liver homogenate at $37^{\circ}C$, The $LD_{50}$ value of 5-FU was 240 mg/kg while that of GFU was 440.6 mg/kg (226 mg as 5-FU). Both of 5FU and GFU showed a strong antitumor activity, Therapeutic ratios of 5-FU and GFU were 3.07 and 3.55, respectively.