• 한국식품조리과학회지
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• 제8권3호
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• pp.323-332
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• 1992

This study was carried out to investigate work analysis by use of work sampling and productivity of school feeding at three elementary schools in Seoul. The results were as knows: 1. In the mean work percent of dietitians The direct work functions showed the highest, as the mean work percent was 40.4% for me direct work functions, 29.9% for me indirect work functions and 29.8% for me delays. Among the direct work functions, routine clerical was 30.9%, and receiving was 9.5%. 2. In the mean work percent of bakers The direct work functions (73.5%) marked the highest. Among those, cooking was 41.8%, transportation was 15.9%, and cleaning was 8.5%. 3. In the mean work percent of workers The direct work functions (781%) were me highest. Among those, the decreasing order was cooking (32.3%), cleaning (27.8%), and transportation (13.8%). 4. Work percent per labor hour The work percent per labor hour of dietitians was higher in the morning than in me afternoon, while they continued to work even during the lunch time. Bakers usually worked in me morning, but rarely worked in me afternoon. Workers had lunch and break time after their food service. In me school aided by parents volunteers, the total work time of workers was reduced by an hour and their work percent in me afternoon was high. 5. The number of mea1s served per labor hour was 32.6 meals, and me labor time spent per served mea1 was 1.8 minutes.

• 가정과삶의질연구
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• 제30권5호
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• pp.89-105
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• 2012

The purpose of this study is to analyze working mothers' demand for child care and housekeeping home services, and to investigate the present supply condition of home services in Korea. Data collection was implemented to examine the service demand of working mothers(n=700) in four areas. The data were analyzed with SPSS. The results were as follows: 1) For home-based child-care dispatch services social enterprises are superior to other private service suppliers in terms of the treatment of service workers, wages, and quality control. As for child care service contents, the provision of meals, and casual safeguards were mostly expected. The most important qualification for care providers was found to be in faithfulness, and the certification related with child care was required. An affordable wage range was perceived as ￦3,000~5,000 per hour, and part time services. For the time range, services which commenced before 9 am and terminated after between 5~6 pm were preferred. 2) For housekeeping dispatch services, standard services, including basic cleaning, preparation of meals and side dishes, special cleaning, and washing, were in demand. The required qualifications of housekeeping service providers were similar to those of child care service providers. Possessing certification was not considered as an important quality; however, personality and career type were important factors. An acceptable wage range was ￦3,000~5,000 per hour and part-time services were preferred. In terms of the service time range, services which commenced between 8~9 am and terminated between 5~7 pm were preferred.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제5권9호
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• pp.261-268
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• 2016

현대생활을 영위하는데 있어 자주 애용되는 교통수단인 버스는 실시간으로 정보를 제공해주고 있다. 이러한 BIS 정보 중 도착예정시간에 대한 신뢰성 높은 정보를 얻기 위해서는 교통 환경에 대한 주요 요인들에 대한 분석이 필요하다. 국내 지방자치단체별로 관리를 수행하는 만큼 지역별 정보 분석이 우선시 되어야 한다. 따라서 본 논문에서는 교육, 관광 및 배후도시에 대한 특성을 가지고 있는 순천시를 중심으로 출퇴근, 학교, 시장, 관광 및 기타 다른 영향에 의해 교통 환경에 영향을 미칠 것으로 예상되는 특징을 분석했다. 특징 분석을 위해 BIS에 수집되고 있는 DB 정보에 대한 데이터 정제를 수행했고, 요일별, 일별, 월별, 시간대별로 구분하여 교통흐름에 대한 주요요인에 대한 분석을 수행했다. 지방중소규모의 도시로서 버스전용차선이 운영되지 않는 지역인 순천은 교통흐름과 밀접한 관계를 갖는 버스에 대한 특징 분석을 통해 구간별 교통체증에 대한 분석이 가능할 것으로 예상된다. 또한, BIS의 실시간 정보 제공에 대한 주요요인을 적용하여 활용한다면 보다 신뢰성 있고 정밀한 정보를 제공할 수 있을 것으로 예상된다.

• 산업경영시스템학회지
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• 제44권4호
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• pp.32-42
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• 2021

The printing process can have to print various colors with a limited capacity of printing facility such as ink containers that are needed cleaning to change color. In each container, cleaning time exists to assign corresponding inks, and it is considered as the setup cost required to reduce the increasing productivity. The existing manual method, which is based on the worker's experience or intuition, is difficult to respond to the diversification of color requirements, mathematical modeling and algorithms are suggested for efficient scheduling. In this study, we propose a new type of scheduling problem for the printing process. First, we suggest a mathematical model that optimizes the color assignment and scheduling. Although the suggested model guarantees global optimality, it needs a lot of computational time to solve. Thus, we decompose the original problem into sequencing orders and allocating ink problems. An approximate function is used to compute the job scheduling, and local search heuristic based on 2-opt algorithm is suggested for reducing computational time. In order to verify the effectiveness of our method, we compared the algorithms' performance. The results show that the suggested decomposition structure can find acceptable solutions within a reasonable time. Also, we present schematized results for field application.

• 한국산업보건학회지
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• 제24권3호
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• pp.310-320
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• 2014

Backgrounds: Endotoxin, which found in the outer membrane of the gram-negative bacteria cell wall, makes up almost all of the lipopolysaccharide(LPS). When people are exposed to endotoxin,it can result in diverse health effects such as an airway irritation and inflammation, fever, malaise, bronchitis, allergic asthma, toxic pneumonitis, hypersensitivity lung disease. Cases among the elderly, children or pregnant can occur more frequently than a healthy adult if they are repeatedly exposed to the existing endotoxin. Therefore, we investigated and assessed the environmental characteristics associated with the airborne endotoxin concentration level in six hospital lobbies. Method: Endotoxin from indoor air in six hospital lobbies was measured by an area sampling method and analyzed according to American Society for Testing and Materials International(ASTM international) E2144-01. Total suspended particulate(TSP), carbon dioxide($CO_2$), temperature and humidity were also measured by using direct reading measurements or airborne sampling equipment at the same time. Environmental characteristics were appropriately divided into two or three groups for a statistics analysis. One-way analysis variable(one-way ANOVA) was used to examine a difference of the endotoxin concentration, depending on the environmental characteristics. In addition, only variables with p-value(p<0.25) were eventually designed to the best model by using multiple regression analysis. Results: The correlation analysis result indicated that TSP(p=0.003) and $CO_2$(p<0.0001) levels were significantly associated with endotoxin concentration levels. In contrast, temperature(p<0.068) and humidity(p<0.365) were not associated with endotoxin concentration. Levels of endotoxin concentration were statistically different among the environmental characteristics of Service time(p=0.01), Establishment of hospital(p<0.001), Scale of hospital(p=0.01), Day average people using hospital(p=0.03), Cleaning time of lobby(p=0.05), Season(p<0.001), and Cleaning of ventilation system(p<0.001) according to ANOVA. Finally, the best model(Adjusted R-square=72%) that we designed through a multiple regression test included environmental characteristics related to Service time, Area of lobby, Season, Cleaning of ventilation system, and Temperature. Conclusions: According to this study, our result showed a normal level of endotoxin concentration in the hospital lobbies and found environmental management methods to reduce the level of endotoxin concentration to a minimum. Consequently, this study recognized to be requirement for the management of ventilation systems and an indoor temperature in order to reduce the level of endotoxin concentration in the hospital lobbies.

• 보존과학회지
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• 제25권4호
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• pp.451-464
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• 2009

토기 및 도자기 유물의 표면 오염물을 제거하기 위해서는 경우에 따라 화학적 세척과정이 필요하며, 그 과정은 신중하게 이루어져야 한다. 본 연구에서는 화학적 세척제가 토기 및 도자기에 미치는 영향을 평가하기 위해 침적실험을 수행하여 주성분원소의 용출특성에 대해 정량적인 데이터를 제공하고자 하였다. 연질토기는 재질이 약하고 흡수율이 커서 짧은 침적 시간에도 큰 용출특성을 가졌고 강한 산성에 의해서 표면 박락과 색의 변화가 발생했다. 그러나 이러한 색의 변화는 물리적인 특성에는 영향을 미치지 않았다. 경질토기에서는 용출량이 미비하고 강한 산성에 의한 색차변화와 물리적인 변화가 없는 것으로 확인되어, 세척제에 대해 비교적 안정한 것으로 사료된다. 도자기(청자, 백자, 분청사기)에서는 용출량이 미비하여 시료의 안정성에는 영향을 미치지 않는 것으로 판단된다. 하지만 도자기 유물에서는 빙렬이 용출특성에 관여하는 것으로 확인되어 분청사기 같은 빙렬이 발달된 유물에 적용할 시에는 주의가 필요하다.

• 대한환경공학회지
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• 제28권2호
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• pp.197-206
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• 2006

본 연구에서는 최근 매립지 침출수 처리를 위해 많이 활용되고 있는 막분리 공정에 초음파를 적용하여 투과속도와 막의 세정효율 향상에 미치는 영향인자와 효과에 대하여 살펴보았다. 즉, 중공사 형태의 MF막과 관형의 UF막을 대상으로 초음파의 주파수($40{\sim}120$ kHz), 초음파의 세기($200{\sim}500$ W), 운전압력($0.1{\sim}2.3kg/cm^2$), 초음파 조사시간 등을 변화시키며 투과속도 향상에 미치는 영향을 평가하였다. 1차 처리된 침출수를 이용하여 초기 50 min 동안 막을 오염시킨 다음 70 min 동안 초음파를 조사하여 조사기간과 투과속도의 변화를 관찰하였다. 순수의 투과속도에 대한 투과속도의 회복률(recovery ratio)과 세정직전의 투과속도에 대한 초음파 조사 후 투과속도의 상승률(enhancement ratio)을 이용하여 영향인자를 분석하였다. 동일한 조건에서 막의 초음파 세정에 의한 투과속도 개선 효과는 주파수에 반비례적이며. 초음파의 조사강도에 비례적으로 나타났고, 막의 운전압력이 높으면 세정효과가 지연되며 투과속도의 개선효과도 감소하였다. 또한 10,000과 100,000 MWCO의 UF막에서의 회복율과 상승률은 각각 최대 75-98%와 40-50% 이었으나, $0.1{\mu}m$ MF막에서는 각각 10%와 500%였다. 1차 처리 침출수를 이용한 실험결과로부터 초음파에 의해 발생되는 기계적 진동을 활용한 막세정이 기존의 수세정과 약품세정 대신에 활용가능성이 확인되었다.

• 상하수도학회지
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• 제31권6호
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• pp.539-549
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• 2017

In water treatment process using microfiltration membranes, manganese is a substance that causes inorganic membrane fouling. As a result of analysis on the operation data taken from I WTP(Water Treatment Plant), it was confirmed that the increase of TMP was very severe during the period of manganese inflow. The membrane fouling fastened the increase of TMP and shortened the service time of filtration or the cleaning cycle. The TMP of the membrane increased to the maximum of $2.13kgf/cm^2$, but it was recovered to the initial level ($0.17kgf/cm^2$) by the 1st acid cleaning step. It was obvious that the main membrane fouling contaminants are due to inorganic substances. As a result of the analysis on the chemical waste, the concentrations of aluminum(146-164 mg/L) and manganese(110-126 mg/L) were very high. It is considered that aluminum was due to the residual unreacted during coagulation step as a pretreatment process. And manganese is thought to be due to the adsorption on the membrane surface as an adsorbate in feed water component during filtration step. For the efficient maintenance of the membrane filtration facilities, optimization of chemical concentration and CIP conditions is very important when finding the abnormal level of influent including foulants such as manganese.

• 대한치과교정학회지
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• 제47권4호
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• pp.238-247
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• 2017

Objective: The aim of this study was to compare recycled and unused orthodontic miniscrews to determine the feasibility of reuse. The comparisons included both miniscrews with machined surfaces (MS), and those with etched surfaces (ES). Methods: Retrieved MS and ES were further divided into three subgroups according to the assigned recycling procedure: group A, air-water spray; group B, mechanical cleaning; and group C, mechanical and chemical cleaning. Unused screws were used as controls. Scanning electron microscopy, energy-dispersive X-ray spectrometry, insertion time and maximum insertion torque measurements in artificial bone, and biological responses in the form of periotest values (PTV), bone-implant contact ratio (BIC), and bone volume ratio (BV) were assessed. Results: Morphological changes after recycling mainly occurred at the screw tip, and the cortical bone penetration success rate of recycled screws was lower than that of unused screws. Retrieved ES needed more thorough cleaning than retrieved MS to produce a surface composition similar to that of unused screws. There were no significant differences in PTV or BIC between recycled and unused screws, while the BV of the former was significantly lower than that of the latter (p < 0.05). Conclusions: These results indicate that reuse of recycled orthodontic miniscrews may not be feasible from the biomechanical aspect.

• Journal of Biosystems Engineering
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• 제40권2호
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• pp.145-152
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• 2015

Purpose: The inability to adequately judge the efficacy of cleaning and sanitation procedures in deli departments is a recognized food safety concern. In a prior study, our research group demonstrated that visual inspection of cleaned produce processing surfaces could be enhanced through the use of a portable fluorescence imaging device that detected residual produce residues. Methods: To explore the feasibility of using fluorescence imaging to similarly detect residual deli residues, spectra of American, Cheddar, Provolone, and Swiss cheeses and of processed chicken, ham, roast beef, and turkey were acquired using a laboratory hyperspectral imaging system. Circular punches of these commodities were placed onto stainless steel and high density polyethylene coupons for imaging. The coupon materials were selected to represent common surfaces found in deli departments. Results: Analysis of hyperspectral fluorescence images showed that cheeses exhibited peaks in the blue-green region and at around 675 nm. Meats exhibited peaks in the blue-green region with one of four ham and one of four chicken brands exhibiting peaks at around 675 nm, presumably due to use of plant-derived additives. When commodities were intermittently imaged over two weeks, locations of spectral peaks were preserved while intensity of peaks at shorter wavelengths increased with time. Conclusion: These results demonstrate that fluorescence imaging techniques have the potential to enhance surface hygiene inspection in deli departments and, given the immediate availability of imaging results, to help optimize routine cleaning procedures.