• Fire Science and Engineering
• /
• v.13 no.3
• /
• pp.3-17
• /
• 1999

Smoldering is a non-flaming combustion mode, characterized by thermal degradation and c charring of the virgin material, evolution of smoke and emission of visible glow. A big fire may @ occur even in a confined environment having a limited amount of oxygen, due to smoldering c combustion through a porous solid material. This paper presents a theoretical analysis on the effect of smoldering combustion on fire occurrence based on a report about fire investigation of a real f fire accident. It is assumed that the propagation of the smolder wave is one-dimensional, d downward, opposing an upward forced flow and steady in a frame of reference moving with the s smolder wave. Smoldering combustion is modeled by a one-step reaction mechanism, without c considering pyrolysis. It is found that dominant parameters controlling smoldering combustion i include mass flux of oxidizer entering the reaction zone and void fraction of solid fuel. It is also found that the mechanism of transition to flaming is critically influenced by these two parameters.

• Radiation Oncology Journal
• /
• v.27 no.2
• /
• pp.84-90
• /
• 2009

Purpose: The effect of concurrent chemoradiotherapy was analyzed in elderly patients when used in the treatment of locally advanced esophageal cancer. Materials and Methods: The retrospective analysis included 28 elderly patients aged 65 or older, with histopathologically confirmed squamous cell carcinoma of the esophagus, underwent concurrent chemoradiotherapy from January 2001 to July 2007. The squamous cell carcinoma disease stages included 8 patients (28.8%) in stage IIa, 10 patients (35.7%) in stage IIb, and 10 patients (35.7%) in stage III. Fractionated radiotherapy was performed with a 6 MV or 10 MV X-ray for 45~63 Gy (median: 59.4 Gy). Chemotherapy was applied concurrently with the initiation of radiotherapy. A 75 mg/$m^2$ dose of Cisplatin was intravenously administered on day 1. Further, 5-FU 1,000 mg/$m^2$ was continuously administered intravenously from days 1 to 4. This regimen was performed twice at 3-week intervals during radiotherapy. Two cycles of consolidation chemotherapy was performed after radiotherapy. Results: The follow-up period was 3~72 months (median: 19 months). The treatment responses after concurrent chemoradiotherapy included a complete response in 11 patients (39.3%), a partial response in 14 patients (50.0%), and no response in 3 patients (10.7%). The overall response rate was 89.3% (25 patients). The overall 1-, 2- and 3-year survival rates were 55.9%, 34.6% and 24.2%, respectively. The median survival time was 15 months. Two-year survival rates of patients with a complete response, partial response, and no response were 46.2%, 33.0%, and 0%, respectively. The stage and tumor response after concurrent chemoradiotherapy were statistically significant prognostic factors related with survival. No treatment-related deaths occurred in this study. Conclusion: Concurrent chemoradiotherapy is a relatively effective treatment without serious complications in elderly patients with locally-advanced esophageal cancer.

• Applied Chemistry for Engineering
• /
• v.10 no.2
• /
• pp.259-262
• /
• 1999

The copper-catalyzed reaction of silicon with methanol was carried out in a mixed bed reactor to obtain tetramethyl orthosilicate (TMOS). In order to determine the kinetics of the reaction per active site on the silicon surface, a flow rate transition technique was employed. A kinetic study showed the reaction was in Linear relationship with the amount of contact mass and independent on the concentration of methanol. This result indicated that the rate-determining step was not the chemical process involving methanol, but the formation of silicon intermediate on the contact mass. On the basis of optimum experimental conditions, the maximum TMOS formation rate per g-silicon is 0.030 (g/min) at $210^{\circ}C$, in which activation energy was 8.5 kcal/mol and reaction rate equation was $k=4.09{\times}10^4\;exp$ ($-4.73{\times}10^3/T$).

• Radiation Oncology Journal
• /
• v.25 no.4
• /
• pp.193-200
• /
• 2007

Purpose: This study evaluated the pretreatment expression patterns of MDM2, p53, and pRb proteins to determine if the expression patterns could predict the outcome of concurrent chemoradiotherapy (CCRT) for esophageal squamous cell carcinoma and aid in the decisions for the selection of treatment modalities. Materials and Methods: Fifty-one patients that were treated with definitive chemoradiotherapy for stage $I{\sim}IVa$ esophageal squamous cell carcinoma were selected for this study. Radiotherapy was administered with daily $1.8{\sim}2\;Gy$ fractions up to a median dose of 54 Gy for primary tumors, and with four cycles of cisplatin/5-fluorouracil chemotherapy that was administered every 4 weeks, the first two cycles of which were administered concurrently with radiotherapy. Expression of MDM2, p53, and pRb was investigated by immunohistochemical analysis using pretreatment biopsy specimens. Results: MDM2, p53, and pRb were detected with high immunoreactivity in 19.6%, 27.5%, and 66.7% of the patients, respectively. However, there was no significant correlation between expression of these factors and clinical outcome. By the use of multivariate analysis with nine covariates-age, tumor location, tumor length, stage, pathological response, clinical response, MDM2 expression, p53 expression, and pRb expression, only pathological response and stage were significant factors for cause-specific survival. Conclusion: Expression of MDM2, p53, and pRb was not found to be clinically significant for predicting outcomes after CCRT in this study. Further studies with a larger patient population and longer follow-up periods are needed to re-evaluate the expression pattern and to identify new predictors for CCRT response.

• Tuberculosis and Respiratory Diseases
• /
• v.41 no.4
• /
• pp.363-371
• /
• 1994

Background: DNA content analysis of human solid tumor is now widely performed by flow cytometric study. One of the most interesting and potentially important observation in this field is that proliferative activity(S-Phase fraction of cell cycle) may profoundly affect the prognosis. Method: S-Phase fraction(SPF) have been measured by flow cytometric method using tumor cells isolated from paraffin embedded tissue. To evaluate the prognostic significance, SPF of small lung cancer cell was assessed in 42 patients who died after receiving anticancer chemotherapy. Results: 1) Mean survival time of patients with small cell lung cancer was 190(${\pm}156$) days. Survival time were shortened, when TNM stage and PS scale were advanced. 2) Mean value of SPF of patients with small cell lung cancer was 27.4(${\pm}8.5$)%. SPF had nothing to do with advance of TNM stage and PS scale. 3) In each identical TNM stage, there were not statistic significance between SPF and survival times. 4) There was a tendency like that higher SPF, better chemotherapeutic response. Conclusion: We could not find statistic significance between SPF and survival times, but SPF was a good predictive factor for chemotherapeutic response.

• Applied Chemistry for Engineering
• /
• v.29 no.5
• /
• pp.565-570
• /
• 2018

In this study, the antioxidant was extracted from Broussonetia kazinokii using ultrasound-assisted extraction (UAE) and optimized by using a response surface methodology. The response value of the central composite design model establishes the extraction yield and the DPPH radical scavenging activity. The extraction time and temperature and volume ratio of ethanol/ultrapure water were selected as quantitative factors. When considering both the main and interaction effects, the factor having the greatest influence on the extraction yield and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was the volume ratio of ethanol/ultrapure water. The results of optimal extraction conditions were the extraction time (19.92 min), volume ratio of ethanol/ultrapure water (54.23%), and ultrasonic irradiation power (557.65 W). We could also obtained expected results of the yield = 38.93 wt% and DPPH radical scavenging activity = 55.33% under these conditions.

• Tuberculosis and Respiratory Diseases
• /
• v.43 no.4
• /
• pp.536-546
• /
• 1996

Background : The survival benefit of combination chemotherapy comparing supportive care to patients with advanced non-small cell lung cancel, especially stage IV non-small cell lung cancer patients with metastatic disease, is controversial. The main goal of this study was to evaluate the difference in survival between patients treated with chemotherapy and those who were not and to identify prognostic factors in the patients with stage IV non-small cell lung cancer. Methods : From January 1989 to December 1994, total 67 patients including 20 patients treated with combination chemotherapy and 47 patients treated with only supportive care in stage IV non-small cell lung cancer patients with metastatic disease were enrolled in this study. Combination chemotherapy consisted of etoposide $120mg/m^2$ iv for 3 days and cis-platin iv day 1 every 4 weeks. The treatment groups were retrospectively analyzed by age, sex, histologic cell type, weight loss, serum LDH level, ECOG performance status and major organ metastasis. Results : The significant prognostic factors influencing survival on this study were ECOG performance status and histologic subtype. Overall response rate by combination chemotherapy was 30%(complete response 0%, partial response 30%). Median survival of overall patients was 13.6 weeks and median survival of Chemotherapy group, 20 weeks, was significantly longer than that of supportive care group, 11.7 week(p<0.01). Median survival of responded in patients receiving chemotherapy, 45.5 weeks, was significantly longer than that of non-responder, 17.3 weeks(p<0.05). 1 year-survival rate of chemotherapy group and supportive care group was 15N and 8%, respectively. Nausea or vomiting, alopecia and anemia were seen in nearly most cases after this combination chemotherapy. Toxicities above grade 3 included neutropenia, anemia, thrombocytopenia, infection, fever, nausea, vomiting and alopecia. But this combination chemotherapy was relatively well tolerated except one treatment-related death from sepsis associated with severe granulocytopenia. Conclusion : These results suggest that systemic chemotherapy might be helpful to the stage IV non-small cell lung cancer patients with good performance status and large scale randomized prospective trials should be performed.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.283-283
• /
• 2021

혼합대는 지표수와 지하수의 수리적 교환이 일어나는 경계부로써 1) 수문학적 관점에서는 하도와 하상간의 물교환이 이루어지는 공간으로 다양한 물리적·화학적 작용이 발생, 2) 생지화학적인 관점에서는 하상 간극수 흐름에 의한 전이대(ecotone)를 형성하여 용존산소·영양물질·용존유기탄소의 이동뿐만이 아니라 지하수로부터 열에너지·무기염류의 공급을 유도하면서 높은 생지화학적 활동과 변환을 야기하는 산화·환원 반응구역, 3) 생태적인 관점에서는 저서생물과 지하 유기체종을 특징으로 하는 서식지이나 잠재적인 레퓨지움(refugium) 등의 관점에서 해석될 수 있다. 국내 하천환경의 생태학적 지속가능성을 위한 지표수-지하수 혼합대 관리에 대한 중요성이 점차 증대되고 있지만 우리나라는 여전히 지하수의 이용 및 보전과 지하수의 안정적인 수량·수질 확보를 목표로 관리를 추진하고 있다. 따라서, 실질적인 지표수-지하수 혼합대에서 발생하는 다양한 현상의 이해나 관리방안에 관한 연구는 아직 미비한 상황이다. 지표수-지하수 혼합대에 관한 보고서, 논문 등을 종합하여 혼합대의 영향인자를 살펴보면 1) 수리수문 특성에는 수리전도도·하천 수위·하천 유속·하천수 수온, 2) 수질 특성에는 유기오염물질·영양염류, 3) 수생태 특성에는 대형무척추동물 등으로 분류할 수 있다. 지금까지 단일 연구분야의 접근방법으로 다양한 현장측정기법 및 모델링을 통한 혼합대 연구가 수행되고 있지만, 혼합대가 가지는 환경적 중요성에 대한 이해와 인식이 부족하고, 혼합대 내부에서 발생하는 복합적인 프로세스로 인해 전문가들조차 연구에 어려움을 가질 것이다. 지표수-지하수 혼합대의 효율적인 관리를 위해서는 수리수문·수질·수생태 등 다양한 시각에서 접근하여 학제간 융합연구를 통해 기초 데이터를 상호교환하고, 기존의 혼합대 조사에 부족한 부분을 해결할 필요가 있다. 향후 하천 기저유출 및 혼합대 기초자료 구축, 혼합대 흐름 정량화, 하천복원사업에 의한 혼합대 영향 규명 등의 연구를 수행함으로써 혼합대를 체계적으로 관리할 수 있는 기술 방안을 제시할 필요가 있다.

• Microbiology and Biotechnology Letters
• /
• v.44 no.1
• /
• pp.48-54
• /
• 2016

In this study, biosugar production by the red-algae Eucheuma cottonii was investigated using dilute sulfuric acid-catalyzed hydrolysis and data analysis by response surface methodology. This approach yielded 25.8 g/l total reducing sugar under the conditions of $160.1^{\circ}C$, 1% (v/v) sulfuric acid, and 13.1 min. The sugar concentration showed a linear inverse correlation with the combined severity factor (CSF) of the reaction conditions. CSF was calculated as $log(t{\cdot}e{xp}[(T_H-T_R)/14.75])-pH$, where t is the coupling reaction time, $T_H$ is the target temperature, and $T_R$ is the reference temperature ($100^{\circ}C$). In addition, levulinic acid production showed a linear positive correlation with CSF. E. cottonii may represent a useful feedstock for sugar production in the field of bioenergy.

• Applied Chemistry for Engineering
• /
• v.7 no.1
• /
• pp.177-185
• /
• 1996

The optimum conditions for the removal of hydrogen sulfide by Fe-EDTA complex in the bubble column reactor were investigated. As the concentrations of the complex increased, the conversion rate of hydrogen sulfide increased, while Fe concentration and pH were stably decreased and the amount of elemental sulfur produced was also increased. Hydrogen sulfide was removed efficiently when the concentration of Fe-EDTA complex was maintained more than 0.05M. pH acts as an important factor for the stability of complex in the oxidation of hydrogen sulfide and optimum pH range was 8.5~9.5. As the molar ratio of EDTA : Fe was increased, the conversion rate of hydrogen sulfide became stable. However, the rate was decreased due to the precipitation of FeS when the concentration of EDTA was decreased. As the concentration of EDTA increased, the conversion rate of hydrogen sulfide increased due to the high stability of Fe-EDTA complex.