• 대한수학회보
• /
• 제58권2호
• /
• pp.461-479
• /
• 2021

This paper includes a general version of Bessel multipliers in Hilbert C∗-modules. In fact, by combining analysis, an operator on the standard Hilbert C∗-module and synthesis, we reach so-called generalized Bessel multipliers. Because of their importance for applications, we are interested to determine cases when generalized multipliers are invertible. We investigate some necessary or sufficient conditions for the invertibility of such operators and also we look at which perturbation of parameters preserve the invertibility of them. Subsequently, our attention is on how to express the inverse of an invertible generalized frame multiplier as a multiplier. In fact, we show that for all frames, the inverse of any invertible frame multiplier with an invertible symbol can always be represented as a multiplier with an invertible symbol and appropriate dual frames of the given ones.

• 핵의학기술
• /
• 제14권1호
• /
• pp.115-121
• /
• 2010

방사성핵종과 방사능을 측정하는 dose calibrator의 서로 다른 두개의 기기에서 F-18 FDG을 각각 측정하고, 이 측정값에 의한 인체 내 SUV (Standard Uptake Value)에 미치는 영향은 없는지에 대하여 알아보고자 하였다. 이 연구에서 두개의 다른 dose calibrator는 CRC-15 Dual PET, CRC-15R을 사용하였다. 각 dose calibrator에서 F-18 FDG를 2 mL 주사기 3개에 볼륨 1 mL, 2 mL, 3 mL를 만들어 각각 초기 radio activity를 측정한 후 4시간 30분(270분)까지 30분 간격으로 radio activity를 각각 측정하고 기록한다. 초기 radio activity 값을 기준으로 방사선붕괴 공식으로 산출된 값(decay factor)과 dose calibrator로 측정된 값 간의 직선성을 단순선형을 통하여 분석하였다. CRC-15 Dual PET에서 가장 이상적인 값에 가까운 측정값을 볼륨을 기준으로 하여, CRC-15R에서 측정된 값을 최적화하기 위한 선형회귀식을 회귀분석을 통하여 구한다. 선형회귀식의 산출값을 적용하여 PET/CT 검사를 시행한 50명을 대상으로 lung, liver, region 부위에 ROI을 그려 SUV를 구한다. CRC-15 Dual PET, CRC-15R에서 측정한 radio activity와 그 값을 이용한 SUV를 paired t-test로 통계적으로 유의한 차이가 있는지 알아보았다. CRC-15 Dual PET과 CRC-15R에서 측정한 radio activity의 상관분석결과 1 mL의 경우 상관성을 보여주는 r값은 r=0.999이었으며, 회귀분석에 위한 선형식은 y=1.0345x+ 0.2601이었다. 2 mL의 경우 r=0.999이며, 선형회귀식은 y=1.0226x+0.1669이었다. 3 mL의 경우 r=0.999이며, 선형회귀식은 y=1.0094x+0.1577이었다. 각 세 가지 볼륨에서 얻어진 선형회귀식의 산출 값을 이용하여 구한 lung, liver, region 부위에 ROI의 SUV에서의 차이는 1 mL의 경우, lung, liver, region은 (p<0.0001)로 t-test 결과 모두 유의한 차이가 있었다. 2mL의 경우, lung (p<0.002), liver, region은 ROI의 SUV에서 유의한 차이(p<0.0001)를 보였다. 또한 3 mL의 경우, lung(p<0.044), liver, region의 유의한 차이(p<0.0001)가 있었다. F-18 FDG 검사에서 사용되는 두 개의 dose calibrator CRC-15 Dual PET, CRC-15R의 radioactivity에 대한 측정치에서는 상관관계의 차이가 없다는 것을 알 수 있었다. 그러나 이 두 값을 통해 SUV는 인체 내의 uptake 정도에 있어서는 유의한 차이를 보인다는 것을 알 수 있었다. 따라서 이 두개의 dose calibrator를 사용함에 있어서, 이 두 값이 인체 내 SUV의 차이를 고려하여 사용하여야 할 필요성이 요구된다.

• 상하수도학회지
• /
• 제28권3호
• /
• pp.287-297
• /
• 2014

It is important to predict chlorine decay with different water purification processes and distribution pipeline materials, especially because chlorine decay is in direct relationship with the stability of water quality. The degree of chlorine decay may affect the water quality at the end of the pipeline: it may produce disinfection by-products or cause unpleasant odor and taste. Sand filtrate and dual media filtrate were used as influents in this study, and cast iron (CI), polyvinyl chloride (PVC), and stainless steel (SS) were used as pipeline materials. The results were analyzed via chlorine decay models by comparing the experimental and model parameters. The models were then used to estimate rechlorination time and chlorine decay time. The results indicated that water quality (e.g. organic matter and alkalinity) and pipeline materials were important factors influencing bulk decay and sand filtrate exhibited greater chlorine decay than dual media filtrate. The two-component second-order model was more applicable than the first decay model, and it enabled the estimation of chlorine decay time. These results are expected to provide the basis for modeling chlorine decay of different water purification processes and pipeline materials.

• 한국경영과학회지
• /
• 제3권1호
• /
• pp.31-46
• /
• 1978

Consider a time interval during which the demand for trips is fixed (e.g. the rush hour period). The traveller has a choice between various public modes, whose travel times and fares are fixed, and the automobile mode, for which travel time and cost depend on the volume of traffic flow on those roads, which are subject to congestion. We consider the equilibrium in terms of a representative travellerm, who choses for any trip the mode and route with the least combined money and time cost. When several (parallel) model or routes are chosen, then the combined cost of money and time must be equal among these. Our problem is first, to find the optimal flows of cars and of public mode carriers on the various links of their networks and second the optimal fares for trips by the variousmodes. The object is to minimize the total operating costs of the carriers and car plus the total time costs to travellers. The optimal fares are related to, but not identical with the dual variables of the underlying Nonlinear Program. They are equal to these dual variables only in the case, when congestion tolls on trips or on the use of specific roads are collected from automobile users. When such tolls are not collected, they must be passed on as subsidies to travellers using competing modes. The optimal fares of public modes are then reduced by the amounts of these subsidies. Note that subsidies are not a flat payment to public carriers, but are calculated on the basis of tickets sold. Fares and subsidies depend in general on tile period considered. They will be higher during periods of higher demand. When the assumption of fixed trip demand is relaxed, this tare system is no longer best, but only second best since too much traffic will, in general, be generated. The Free Rider Theorem states the following : Suppose road tolls can be charged, so that a best pricing system for public modes is posssible. Then there may exist free rides on some routes and modes, but never on a complete round trip.

• 한국항공우주학회지
• /
• 제35권9호
• /
• pp.799-804
• /
• 2007

액체추진제 추력기 연소실의 인젝터로부터 발생하는 분무 거동을 파악하기 위하여 광학계측 기법을 사용한다. 실험에 사용된 인젝터는 지름이 0.406 mm이며 중심축으로부터 30 의 경사각을 이루는 8 개의 노즐 구멍으로 구성된다. 분무생성의 초기조건과 분무발달에 따른 미립화 과정을 분석하기 위해, 이중모드 위상도플러속도계(DPDA)로 측정된 액적의 속도 및 입경 등의 변이 거동을 제시하고 Nd:Yag 레이저평면광에 의해 획득된 순간평면이미지와 함께 고찰한다. 분무액적의 초기 분사속도에 근거한 Re 수와 We 수 등의 무차원 변수를 도출하여 인젝터 발생 분무의 미립화 및 난류성질 등에 대한 분무유동 양식의 범주를 결정한다. 이러한 분무분열에 대한 정성적, 정량적 결과는 향후 새로운 추력기 개발에 확실한 설계 기반을 제공할 것이다.

• 대한한의학회지
• /
• 제36권1호
• /
• pp.61-74
• /
• 2015

Objectives: The main purpose of this study is to find a solution for modernized classification of herbal medicinal preparations in dual medical systems. Through this study, we expect to provide a reasonable foundation of herbal medicine for public health. Methods: We studied legal or technical terms of herbal medicinal preparations from the past regulations, and through this procedure, we could suggest clear definitions of terms for herbal medicinal preparations. We also investigated documents for approval of herbal medicinal preparation from US, EU(European union), The People's Republic of China, Japan, so that we can refer to them to revise regulation for appropriate use of herbal preparations. Results: In Korea pharmaceutical affairs act, any basis of 'Crude drugs' does not exist. But in some subordinary notifications, the way that they use the 'Natural product medicine' is used as a means of limiting basic rights of doctor or pharmacist of Korean medicine compared to doctor or pharmacist. At the same time, in subordinary notifications, provisions are vague and not enough for scientific evidence of Korean medicine. Thus, we re-categorized herbal medicinal preparations into new drugs, drugs made from herbal medicinal preparations and suggested requirements for drug approval. Conclusions: Instead of using the term 'Crude drug preparations', and we should use term 'Herbal medicinal preparations' in related act and notification. And also we suggest to amend subordinary regulations and documents for approval of herbal medicinal preparations. Through this, we can make herbal medicinal preparations be more industrialized.

• 콘크리트학회논문집
• /
• 제25권2호
• /
• pp.175-185
• /
• 2013

최근 다른 압축강도로 타설된 프리캐스트 콘크리트(PC)와 현장타설 콘크리트(CIP)의 복합 부재의 사용이 증가하고 있지만 현행 기준에는 서로 다른 강도로 복합화된 부재의 전단강도에 대한 설계 기준이 없다. 그래서 이번 연구에서 서로 다른 압축강도(24 MPa, 60 MPa)로 분리 타설된 보의 전단강도 실험을 수행하여 복합 부재의 전단강도에 대해 알아보았다. 변수로는 단면형상, 휨철근비, 그리고 전단경간비를 고려하였다. 실험 결과 값과 현행 전단 기준식과 단면적비로 계산한 유효 콘크리트 강도를 이용한 예측 값을 비교하였다. 실험 결과를 분석해보면 철근비가 낮고 압축대에 60 MPa가 사용된 실험체들에 대해 설계 기준식을 과대평가하였다. 실험 결과를 기준으로 PC와 CIP 복합부재의 전단설계 기준을 제안하였다.

• 한국지진공학회논문집
• /
• 제15권1호
• /
• pp.39-48
• /
• 2011

본 연구에서는 복강판-모듈러 시스템과 같이 구조 기준에 명시되지 않은 새로운 시스템의 반응수정계수를 산정하는 절차를 제안하였다. 기본 개념은 구조성능 실험결과를 바탕으로 모델링 된 시스템의 비선형 정적 해석 곡선으로부터 세부 구성요소인 초과강도계수와 연성계수의 도출하고, 단자유도 시스템으로 간주하고 평가된 반응수정계수를 다자유도 동적 거동을 고려한 다자유도 밑면전단 수정계수로 수정하여 시스템의 최종적인 반응수정계수를 결정하는 것이다. 제안한 절차에 따라 이중골조시스템으로 설계된 2층부터 5층까지의 복강판-모듈러 시스템에 대해 평가한 결과, 최종적인 반응수정계수는 5층(층고 4m기준)을 복강판-모듈러 시스템의 적용 가능한 층수의 상한으로 하여 4로 결정하는 것이 타당할 것으로 판단하였다.

• Safety and Health at Work
• /
• 제8권1호
• /
• pp.77-83
• /
• 2017

Background: In contemporary China, most parents are dual-earner couples and there is only one child in the family. We aimed to examine the associations of parents' work stress with suicidal ideation among the corresponding adolescent. We further hypothesized that low parental support experienced by adolescents may mediate the associations. Methods: Cross-sectional data from school students and their working parents were used, with 907 families from Kunming City, China. Stress at work was measured by the effort-reward imbalance questionnaire. Perceived parental support was assessed by an item on parental empathy and their willingness to communicate with the adolescent. Suicidal ideation was considered positive if students reported thoughts about suicide every month or more frequently during the previous 6 months. Logistic regression was used to examine the associations. Results: We observed that parents' work stress was positively associated with low parental support, which was in turn associated with adolescent suicidal ideation. The odds ratio for parents' work stress and adolescent suicidal ideation was 2.91 (95% confidence interval: 1.53-5.53), and this association was markedly attenuated to 2.24 (95% confidence interval: 1.15-4.36) after additional adjustment for parental support. Notably, mothers' work stress levels exerted stronger effects on children's suicidal ideation than those of fathers. Conclusion: Parents' work stress (particularly mother's work stress) was strongly associated with adolescent's suicidal ideation, and the association was partially mediated by low parental support. These results need to be replicated and extended in prospective investigations within and beyond China, in order to explore potential causal pathways as a basis of preventive action.

• Journal of Electrical Engineering and Technology
• /
• 제13권5호
• /
• pp.1778-1790
• /
• 2018

Based on the requirements and characteristics of multi-zone autonomous decision-making in modern power system, fully distributed computing methods are needed to optimize the economic dispatch (ED) problem coordination of multi-regional power system on the basis of constructing decomposition and interaction mechanism. In this paper, four fully distributed methods based on alternating direction method of multipliers (ADMM) are used for solving the ED problem in distributed manner. By duplicating variables, the 2-block classical ADMM can be directly used to solve ED problem fully distributed. The second method is employing ADMM to solve the dual problem of ED in fully distributed manner. N-block methods based on ADMM including Alternating Direction Method with Gaussian back substitution (ADM_G) and Exchange ADMM (E_ADMM) are employed also. These two methods all can solve ED problem in distributed manner. However, the former one cannot be carried out in parallel. In this paper, four fully distributed methods solve the ED problem in distributed collaborative manner. And we also discussed the difference of four algorithms from the aspects of algorithm convergence, calculation speed and parameter change. Some simulation results are reported to test the performance of these distributed algorithms in serial and parallel.