• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.191-195
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• 2005

Propellant remains as outage at engine shutdown contributes no useful impulse to the rocket and produces an unwanted increase in burnout weight. Minimization of outage, is therfore is a basic consideration in attaining the maximum performance capability of my bipropellant liquid rocket. This paper present the calculation procedures of outage and optimum loading propellant mass. And some control methods and measurement techniques for outage are presented.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.1-12
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• 2011

The error of onboard propellants mass which is mostly occupied in total mass of launch vehicle and The error of residual affect the performance of launch vehicle seriously. In other words, the errors directly cause the error of total impulse. Therefore, optimization of performance of launch vehicle can be achieved by the minimization of the residual. For minimizing the residuals, the active control for completely depleting the propellants and the calculation method using probability for minimizing the residuals have been researched. In this paper, the added fuel was calculated for minimizing the residual and the minimized residual was predicted by the presented method.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.463-470
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• 2011

This study was carried out to survey the residual characteristic of chlorpyrifos and estimate their residues in squash before harvest. The pesticide was sprayed onto the crop at the recommended and its double rates 10 days before the prearranged harvest and sampling was done at 0, 2, 3, 5, 6, 7 and 10 days after spraying. The amounts of the chlorpyrifos residue in the crop was analyzed by chromatographic method. Limit of detection (LOD) of chlorpyrifos was 0.005 mg/kg and its recovery ranged from 95.21 to 102.69%. The initial concentration of chlorpyrifos sprayed with recommended dose exceeded its MRL of 0.1 mg/kg but its concentration was less than its MRL 10 days after application. However its concentration in case of the double dose was over its MRL both immediately and 10 days after application. Biological half-lives of chlorpyrifos sprayed onto squash was 2.5 and 2.9 days at the recommended and double doses, respectively. Ten days later, the residual concentration of chlorpyrifos in squash was decreased substantially. The concentration of chlorpyrifos was estimated in squash at the given day using its regression equations. The estimated concentration of chlorpyrifos in case of application with recommended dose was below its MRL at 10 days after application but its concentration in case of application with double dose was over its MRL at 10 days of the prearranged harvest. The rate of the estimated daily intake (EDI) of chlorpyrifos to its acceptable daily intake (ADI) was 282% right after application but it decreased to less than 18% at 10 days of the prearranged harvest.

• Environmental Analysis Health and Toxicology
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• v.21 no.2 s.53
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• pp.185-195
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• 2006

환경오염물질로부터 수생태계 보호를 위한 표준적인 평가 및 관리 수단인 수질환경기준은 오염물질의 독성작용이 일어나는 표적기관에서의 오염물질의 농도에 대한 대체측정치로서 환경 내 오염물질의 농도를 이용해 왔다. 이러한 '외부환경농도에 기반한 접근방법'은 표적기관에서의 독성물질의 농도가 생물체내 농도에 비례하고, 결국 외부환경농도에도 비례할 것이라고 가정한다. 따라서 환경오염물질의 생물이용도나 생물축적 양상의 차이 때문에 고유 독성치를 비교 평가하는데 한계가 있다. 이와 달리 '생물체내 농도에 기반한 접근방법(이하 생체잔류량 접근법)'은 환경오염물질의 생물이용도나 종 특이적 생물축적 양상과 관련된 불확실성을 제거하고, 환경오염물질 고유의 독성을 비교 평가할 수 있게 해준다. 특히 생체잔류량 접근법을 독성동태학 및 독성역학 모델과 함께 사용하는 경우는 실제 현장에서 일어나는 복잡한 노출조건에서의 독성영향을 예측하는데 활용할 수 있다. '생체잔류량 접근법'은 독성기작별 임계잔류량(Critical Body Residue)을 결정함으로써 생물모니터링의 결과를 해석하는데 적용되고 있다. 또한 생태위해성평가를 위해서 필요한 '무영향예측농도(Predicted No-effect Concentration, PNEC)를 예측하기 위한 방법으로 생체 내 잔류량에 기반해서 농도-시간-반응관계를 기술하고, 예측할 수 있는 새로운 유형의 독성역학 및 독성동태학 모델을 제시하고, 생체내 '무영향농도(No Effect Concentration, NEC)'를 추정하게 해 준다. 특히 생체내 NEC는 '무영향관찰농도(No Observed Effect Concentration, NOEC)'와 '영향농도(Effect Concentration, EC)'처럼 분산분석이나 회귀분석모델과 같은 통계적 모델에 기반해서, 농도-반응관계만을 기술할 뿐인 기존 독성모델을 대체할 대안으로 최근에 OECD와 ISO에 의해서 추천되었다.분석을 시행한 결과 인지기능 장애정도 및 MMSEK 점수 증가에 따른 사망위험도는 어느 모형에서도 인지기능 장애정도가 사망에 미치는 위험도는 통계적으로 유의하지 않았다(표 6, 표 7). 이상 본 연구는 농촌지역 노인들에서 인지기능 장애정도가 사망에 미치는 영향을 알아보고자 하였지만, 인지기능 장애정도가 사망에 미치는 영향을 통계적으로 유의하게 고찰하지 못하였다.의한 차이를 보였다. (P<0.05, P<0.001) 5. Excelco로 부식처리된 도재가 5% HF 용액으로 부식처리된 도재보다 부식정도가 더 현저하였다.은 제언을 하고자 한다. 먼저, 학교급식에 대한 식단 작성 시 학생들이 학교에서 제공되기 원하는 식단에 대한 의견을 받고 그 의견에 대한 결과를 게시하여 학생들이 제공되기 원하는 식단을 급식 시 제공하여 학생들이 식단선택에 동참할 수 있는 기회를 주는 것이 바람직하겠다. 또한 영양사는 학급의 반대표와의 정기적인 모임을 가짐으로서 학생들의 불만사항 및 개선 요구사항에대해 서로 의견을 교환하여 설문지조사가 아닌 직접적인 대화를 하여 문제점을 파악하고자 하는 적극적인 자세가 필요하겠다. 특히 아침식사의 결식 빈도가 높았고 이는 급식성과에 부정적인 영향을 줄 뿐 아니라 학교에서 제공하는 음식의 섭취정도에도 영향을 주고 있으므로 학생들에게 학부모와 전담교사 및 학교영양사는 학생들에게 이상적인 아침식사에 대한 교육은 물론이고 아침식사를 실천할 수 있도록 다양한 방안에 대해 함께 연구해야 하겠다. 정부차원에서 학교급식에 아침식사 프로그램을 도입할 수 있는 방안을 연구하고, 아침을 결식하는 학생이 학교에서 수업시작 하기 전에 간단한 식사를 할 수 있는 정책 도입이 필요하다acid의 생성량(生成量)을 측정(測定)하였는데 periodate의 소비량(消費量)은 1.23 mole, formic acid의 생성량(生成量)은 0.78 mole이다.한 경우도 비교적 많이 먹고 있었다(24.3%). 남 여

• The Korean Journal of Pesticide Science
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• v.8 no.1
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• pp.30-37
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• 2004

This study estimated the correlation between surface area/weight ratios and pesticide residues in two varieties of tomato, mini tomato and tomato. The ratios of surface area/weight of mini tomato and tomato were $2.15cm^2g^{-1}$ and $1.00cm^2g^{-1}$ respectively. Pesticide residues were measured with four kinds of pesticide, chlorothalonil WP, chlorothalonil SC, oxadixyl WP, thiophanate-methyl WP. Ie residue amount of mini tomato was $1.4\sim2.4$ times higher than those in tomato regardless of the application date and frequency. The ratios of surface area/weight on tomato varieties played a key role for determining pesticide residue.

• Current Research on Agriculture and Life Sciences
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• v.31 no.4
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• pp.272-279
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• 2013

The dissipation patters of the triazole fungicides flusilazole and myclobutanil in apples were investigated to establish the biological half-lives and pre-harvest residue limits (PHRLs). The residual amounts of the fungicides sprayed with single or triple doses were below the maximum residue limits (MRL) for apples established by Ministry of Food and Drug Safety. The dissipation constants of the fungicides in the apples were 0.0513 for flusilazole and 0.0244 for myclobutanil meaning their biological half-lives were calculated as 6.2-6.7 days for flusilazole and 13.3-24.8 days for myclobutanil. The PHRLs calculated using the dissipation constants indicated that the residual amounts of flusilazole and myclobutanil in the apples at the harvesting date would be below the MRLs if their residual amounts were 0.43 and 0.59 mg/kg, respectively, at 7 days prior to harvesting the apples.

• The Korean Journal of Pesticide Science
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• v.18 no.2
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• pp.61-68
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• 2014

Dissipation constants and half-lives of acaricides etoxazole and flufenoxuron in apples were calculated to establish their pre-harvest residue limits (PHRLs). The acaricides were sprayed on apples with single and triple doses based on safe use guidelines, and their residual patterns in the apple were interpreted using first order kinetics equation. The residual amounts of acaricides during the experimental period were below their maximum residue limits (MRL) for apple. The dissipation constants of acaricides in the apples were calculated at 0.0788 for etoxazole and 0.0319 for flufenoxuron corresponding to their biological half-lives; 8.8~21.7 days for etoxazole and 21.7~23.1 days for flufenoxuron. The PHRLs of acaricides in the apple showed the residual amounts of etoxazole and flufenoxuron at the harvesting date would be below their MRLs if their residual amounts were less than 0.87 and 0.88 mg/kg, respectively, at 7 days prior to harvesting the apples.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.21-28
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• 2018

Despite a number of studies on consolidation behavior that have been carried out in the Nakdong River estuary in Busan, these are focused on the prediction of final settlement during ground improvement process, and there is almost no research on the long-term settlement occurring after that. For the practical study on the long-term settlement, the field monitored settlement data that measured over 10 years in the Busan new port facilities area were used, and the final settlement and predicted time-settlement line were constituted by hyperbolic function. As a result, the measured settlements depend on the thickness of clayey soils, and the pattern were similar to each other and good agreement with the predicted time-settlement line using hyperbolic method. Also, the settlement in the lower non-improved layer occupied 62-76% of total settlement. Information about above results would be quite helpful to understand the long-term settlement behaviors as well as the non-improved layer's settlement is more careful consideration needed at design phase.

• The Korean Journal of Pesticide Science
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• v.17 no.2
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• pp.77-83
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• 2013

This study was performed to investigate pre-harvest residue limit (PHRL) in amaranth, to estimate biological half-life of emamectin benzoate and identify the characteristics of the residue. Pesticides of standard and double appplication rate, were sprayed once on amaranth at 0, 1, 2, 3, 5, 7, 10, 14 days before harvest. Amaranth sample was extracted with acetonitrile and partitioned with dichloromethane, and pesticide residues were determined with LC/MS/MS. The limit of detection of emamectin benzoate was 0.01 mg/kg. Recoveries of emamectin benzoate ($B_{1a}$, $B_{1b}$) at two fortification levels of 0.1 and 0.5 mg/kg, $B_{1a}$ were $93.3{\pm}0.7%$ and $93.2{\pm}7.7%$, $B_{1b}$ were $106.6{\pm}1.9%$ and $80.5{\pm}6.6%$, respectively. The biological half-lives of emamectin benzoate were about 2.0 days at standard application rate and 1.7 days at double application rate, respectively. The PHRL of emamectin benzoate were recommended as 0.84 mg/kg for 10 days before harvest.

• Korean Journal of Environmental Agriculture
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• v.21 no.4
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• pp.231-236
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• 2002

We studied the residual patterns of two fungicides, dichlofluanid and iprodione, in cherry tomato greenhouse after applying with the recommended and double dose. Also, the degradation patterns during storage periods of up to ten days were compared between at room temperature (20$^{\circ}C$) and at cold temperature (4$^{\circ}C$). Removal rates of fungicides by washing with tap-water and detergent solution (0.1%, 0.2%) were measured. Half-lives of dichlofluanid and iprodione in greenhouse cherrytomato were 2.2$\sim$3.5 and 3.3$\sim$5.4 days, respectively. During the storage period, the residues were dissipated more slow. Removal rates were 62.8$\sim$80.3% by tap-water, 60.4$\sim$83.1% by 0.1% detergent solution, and 65.3$\sim$77.6% by 0.2% detergent solution. So, we can predict of terminal residues from cultivation period to marketing, storage and consuming.