• Journal of the Korean Wood Science and Technology
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• 제33권3호통권131호
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• pp.64-71
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• 2005

본 실험에서는 초음파의 특성을 이용하여 목재를 방부처리하고 그 주입효과에 대해 검토하고자 하였다. 유용성 방부제인 NCU (나프텐산 구리)와 수용성 방부제 AAC (알킬암모늄 화합물)에 소나무 및 잣나무 시편을 침지한 후 40 kHz, 400 W 출력의 초음파를 발진시켰다. 초음파처리 이후 시편의 흡수율 및 침윤도는 시간 경과에 따라 지속적으로 증가하여 120시간 경과 후 AAC처리 잣나무, 소나무 모두에 대해 약 95%의 흡수율을 얻을 수 있었으며, 소나무 및 잣나무 각 시편 두께의 95, 83%에 해당하는 NCU의 침윤도를 얻을 수 있었다. 초음파 처리후의 시편을 SEM을 이용해 관찰하였으며, 초음파 발생에 의해 생성된 고온, 고압의 충격파가 목재 내 약액의 주입통로가 되는 벽공구를 파괴하고 초음파의 탈포작용과 목재내 추출물의 배출 등에 기인하여 약액의 주입성능이 향상된 것으로 판단된다. 초음파 처리에 의한 방부제의 주입은 가압방부처리의 적용이 어려운 소재, 단판 등에 적용이 가능할 것으로 판단된다.

• 공업화학
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• 제17권3호
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• pp.317-320
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• 2006

본 연구에서는 HCI프로그램을 이용하여 여섯 가지 퓨린 유도체(caffeine, guanine, hypoxanthine, purine, theobromine, and theophylline)의 최적 분석 조건을 결정하였다. 이동상으로 물과 메탄올을 사용하는 역상 HPLC를 사용하였다. 체류모델로는 Snyder, Langmuir, Binary polynomial 중에서 체류인자를 가장 잘 예측한 Binary polynomial을 사용하였고 용출곡선을 계산하기 위해서는 단 이론(plate theory)을 사용하였으며 모든 계산은 HCI 프로그램을 이용하여 계산하였다. 이동상의 조건은 일정용매조성법(isocratic mode)과 계단함수 구배용매조성법(step-gradient mode)을 이용하였다. 일정용매조성법에서 물과 메탄올의 조성비가 93/7 (v/v)일 때 최적 분석조건을 얻을 수 있었다. 분석시간의 단축을 위하여 계단함수 구배용매조성법을 사용하여 이동상의 조성을 물/메탄올 93/7 (v/v)에서 5 min 후에 75/25 (v/v)로 변경하는 최적조건을 계산했다. 위의 두 조건에서 실험을 수행하여 계산 용출 곡선과 실험값을 비교하였으며, 매우 잘 일치함을 보였다.

• 한국환경농학회지
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• 제22권4호
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• pp.251-254
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• 2003

Phosphorous removal rate and emergent plant growth were examined of a surface-flow constructed treatment wetland system, whose dimensions were 31 meter in length and 12 meter in width. The system was established on floodplain in the down reach of the Kwangju Stream in Korea in one and half months from May to June 2001. Cattails(Typha angustiflora) were transplanted in the system. They were dug out of natural wetlands and stems were cut at about 40 cm height from their bottom ends. Water of the Kwangju Stream were funneled into it via a pipe by gravity flow and its effluent were discharged back into it. The stems of cattails grew from 45.2 cm in July 2001 up to 186 cm in September 2001 and the number of cattail stems per square meter increased from 22 in July 2001 to 53 in September 2001. The early establishment of cattails was good. Volume and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Inflow averaged $40\;m^3/day$ and hydraulic retention time was about 1.5 days. The concentration of total phosphorous in influent and effluent was 0.85 mg/L, 0.41 mg/L, respectively. The average removal rate of total phosphorous in the system was about 52%. The retention efficiency was slightly lower, compared with that in surface-flow wetlands operating in North America, whose retention efficiency was reported to be about 57%. The lower abatement rate could result from the initial stage of the system and inclusion of two cold months into the six-month monitoring period. Root rhizosphere in wetland soils and litter-soil layers on bottoms were not properly developed. Increase of standing density of cattails within a few years will establish both root zones and substrates beneficial to the removal of phosphorous, which may lead to increase of the phosphorous retention rate. The system was submerged one time by heavy storm during the monitoring period. The inundation, however, scarcely disturb its environment.

• 여성건강간호학회지
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• 제25권3호
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• pp.329-344
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• 2019

Purpose: This study aimed to identify utilization of the work-family support policy (WFSP) and factors affecting retention intention among Korean female military officers. Methods: This cross-sectional survey recruited 103 married female officers from the Korean Army, Navy, and Air force with preschool-aged children through convenience and snowball sampling. Via online surveys from June to November, 2018, the participants self-reported retention intention, work-family conflict, job satisfaction, and utilization of the WFSP. The data were analyzed using descriptive statistics, independent t-tests, one-way analysis of variance, Pearson's correlation coefficient, and multiple linear regression. Results: Retention intention ($22.29{\pm}5.98$) was reported at the mid-level, lower than scores reported in the literature for female workers. Work-family conflict ($32.51{\pm}5.29$) and job satisfaction ($63.10{\pm}7.45$) were above the midpoint levels. Use of maternity leave (100.0%) and parental leave (92.2%) was high, especially compared to the rates of child-care day off (20.4%) and parenting time (20.4%). 'Noticeable increases in childcare services within the army' (22.8%) was reported as the supportive measure needed the most by female military officers. Job satisfaction (${\beta}=.43$, $p{\leq}.001$), the use of parenting time (${\beta}=-0.29$, p=.002), living type (${\beta}=-.18$, p=.043), and service type (${\beta}=-.16$, p=.035) significantly influenced retention intention. Conclusions: The findings highlight the priority areas of importance within the WFSP and suggest that a family-friendly culture can improve female officers' retention intention. Accordingly, policy changes at the Ministry of National Defense improving the system to enhance a family-friendly culture in the military is expected to strengthen the retention intention of female officers and contribute to excellence in the military workforce.

• 한국세라믹학회지
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• 제34권12호
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• pp.1261-1267
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• 1997

Four kids of powder admixtures(A, B, C, D) based on anhydrite were manufactured by mixing at a fixed rate of II-anhydrite, fly ash and active silica as an industrial by-product. Fluidity properties of cement paste such as mini-slump, apparent viscosity with elapsed time, as well as setting time of cement pastes of these admixtures substituted up to 11wt% of cement were compared to those of cement paste(SS) substisuted by marketed high-strength powder admixture(S). Among these powder admixtures, the fluidity of cement pastes(PA, PC) substituted by A and C powder admixtures manufactured from II-anhydrite and fly ash had an excellent property than that of cement paste substituted by marketed powder admixture and also a good fluidity-retention effect with elapsed time by adding of superplasticizer. The setting time of cement paste substituted by powder admixtures based on anhydrite slightly retarded than that of cement paste substituted by marketed powder admixture.

• Management Science and Financial Engineering
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• 제16권3호
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• pp.49-70
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• 2010

Customer population management models can be classified into three categories: the first category includes the models that analyze the customer population at cohort level; the second one deals with the customer population at aggregate level; the third one has interest in the interactions among the customer populations in the competitive market. Our study proposes a model that can analyze the dynamics of customer population in consumer-durables market at aggregate level. The dynamics of customer population includes the retention curves from the purchase or at a specific duration time, the duration time expectancy at a specific duration time, and customer population growth or decline including net replacement rate, intrinsic rate of increase, and the generation time of customer population. For this study, we adopt mathematical ecology models, redefine them, and restructure interdisciplinary models to analyze the dynamics of customer population at aggregate level. We use the data of previous research on dynamic customer population management at cohort level to compare its results with those of ours and to demonstrate the useful analytical effects which the precious research cannot provide for marketers.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.58-59
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• 2018

In this study, firing experiments were carried out to confirm the foamability of the expansive shale collected from the local area. When expansive shales are subjected to high temperature heat, gas is generated inside and voids are formed. Due to this phenomenon, shale is used as a raw material for lightweight aggregate. Experiments were carried out with different plastic temperature and residence time to find the appropriate plastic temperature for this expansive shale. As a result, the higher the plastic temperature, the more the surface viscosity increased and the gas generated inside were retained. Resulting in a number of internal voids. However, even if the plastic temperature or the medium temperature is high, it is confirmed that sufficient gas is not generated when the residence time is shortened.

• Asian-Australasian Journal of Animal Sciences
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• 제16권4호
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• pp.529-533
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• 2003

The intake, dry matter (DM) digestibility, total mean retention time (TMRT) and weight changes were investigated in four fat tailed and four Dorper sheep fed on a maize stover crop residue. Animals were subjected to five dietary treatments, which were: 90, 135 and $180g\;DM/kgBW^{0.75}/day$ of chopped maize stover offered with urea, and in subsequent dietary treatments $180g\;DM/kgBW^{0.75}/day$ of stover supplemented with either dried bean husks or poultry manure. Although not statistically different (p>0.05) fat tailed sheep had higher maize stover intake than the Dorper sheep when expressed per metabolic body weight. The DM intake and digestibility increased significantly (p<0.001) in both sheep breeds when the maize stover offer levels were increased from 90 to $135g/kgBW^{0.75}/day$. Dorper sheep had significantly (p<0.001) higher DM digestibility and longer total mean retention times for both the liquid and solid matter than the fat-tailed sheep. Fat-tailed sheep gained 4.75 kg while Dorper sheep gained 3.75 kg over the entire experimental period. The weight change per dietary treatment was affected by the amount of maize stover and the type and amount of supplement consumed. The higher DM digestibility and longer total mean retention time in Dorper sheep shows that the breed has adapted to utilize the low quality roughage diets. An indigenous fat tailed, has the potential to ingest high volumes of fibrous feed and has higher voluntary intakes relative to its body size. The two sheep breeds are a valuable genetic resource in sub Saharan Africa that is characterized by long dry season with no readily available and affordable conventional feeds for small ruminants.

• 유기물자원화
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• 제8권3호
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• pp.124-130
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• 2000

본 연구는 가솔린 휘발가스를 퇴비 바이오필터로 처리시 공정조절 인자인 체류시간과 충전깊이의 영향을 살펴보고 공정개선방안을 제시하고자 실시하였다. 체류시간을 4, 10, 그리고 20분으로 변화하여 실시한 결과 TPH의 효율적 제거를 위해서는 10분이상의 EBRT가 요구되었으며 $40g/m^3$(충전물질)/hr 미만의 부하로 운전하는 것이 효과적이었다. BTEX는 체류시간 4분에서는 부하량이 약 $1.5g/m^3$(충전물질)/hr 이상으로 증가하자 더 이상 제거 능력이 증가하지 않았으며, 체류시간 10분에서는 약 $5.3g/m^3$(충전물질)/hr의 부하량에서 $4.5g/m^3$(충전물질)/hr 이상이 제거되었다. 이로써 안정적인 제거를 위해서는 BTEX도 10분 이상의 체류시간이 필요하였다. 충전깊이는 25, 50, 75, 그리고 100cm로 하였다. TPH 제거량을 증가시키기 위해서는 단순히 충전깊이를 증가시키는 것보다 가스체류시간 및 유입부하량 등 다른 공정인자들을 제어하는 것이 더욱 효과적이었다. BTEX의 경우에는 다른 공정인자의 조절도 중요하지만 충전깊이를 1m 정도로 하면 다른 공정인자의 조절에 큰 어려움 없이도 제거효율을 향상시킬 수 있을 것이다.

• 한국식품과학회지
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• 제37권3호
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• pp.360-363
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• 2005

가시오가피에서 Polyacetylene 성분 중 falcarinol을 탐색하기 위해 TLC, HPLC/PDA, GC, GC/MS를 이용하여 falcarinol 표준품과 소분획물 사이의 비교 분석을 통하여 가시오가피에서 falcarinol을 동정하였다. 가시오가피 추출물을 silica gel column상에서 용매의 극성차이에 의해 6개의 분획물을 얻었고, 6개의 분획물과 falcarinol 표준품과의 TLC 상에서 전개시킨 결과 fraction 6 분획물에서 falcarinol과 동일 band의 물질을 분리하였다. Fraction 6의 분획물과 falcarinol 표준품을 HPLC/PDA로 분석한 결과 falcarinol 표준품의 peak와 동일 retention time의 peak를 fraction 6에서 분리하여 200-340nm 상에서 UV spectrum을 관찰한 결과 동일한 UV spectrum pattern을 보이는 것을 확인하였다. 이는 전형적인 polyacetylene 화합물의 UV spectrum pattern이었으며, 기존에 보고된 falcarinol의 UV spectrum과도 동일하였다. GC로 TMS 유도체화 전,후의 retention time을 확인한 결과 표준품과 fraction 6에서 동일한 결과를 보였다. TMS 유도체화 후에는 7.5분에서 8.5분으로 약 1분 정도 retention time이 증가하였고, detection 감도 또한 증가하였다. Falcarinol 표준품과 fiaction 6 분획물을 TMS 유도체화 후에 GC/MS로 mass fragment ion을 분석한 결과 표준품과 동일한 경향을 보였고 이는 기존의 보고와도 일치하였다(16). 본 실험결과들로 미루어 가시오가피에도 polyacetylene 성분인 falcarinol 존재하는 것으로 확인되었다.