In order to deal with various environmental conditions, most living organisms adapt and respond to environmental cues through nucleotide-based second-messenger signaling. Such signals regulate various endogenous factors required for environmental adaptation. In bacteria, there are five kinds of nucleotide-based second messengers, one of which is cyclic di-guanosine monophosphate (c-di-GMP). The molecule is known to regulate many cellular functions including growth, motility, biofilm formation, and virulence. Various environmental cues cause changes in the intracellular concentration of c-di-GMP, depending on the activity of specific c-di-GMP synthases and hydrolases in cells. In this review, we provide insights into nucleotide signaling in bacteria, emphasizing its impact on basic metabolism, its association with other signaling mechanisms, and its role in regulating the virulence of a wide range of bacteria. Moreover, we discuss recent studies suggesting a role for the implicated signaling molecules in bacterial persistence and antibiotic resistance.

This study examined the historical changes of and dietitians’ needs for the Life Cycle-based Dietary Guidelines for Koreans. Content analysis of relevant documents, a survey of 307 dietitians, and in-depth interviews with eight dietitians were conducted. The dietary guidelines published between 2003 and 2004 included one set of common guidelines and several sets of dietary action guides corresponding to six target groups: pregnant and lactating women, infants and toddlers, children, adolescents, adults, and the elderly. The guidelines were revised between 2008 and 2011 and consisted of six sets of guidelines for the target groups without common guidelines. The dietitians considered five or six as appropriate numbers of guidelines for each group. Needs for separate guidelines for women of child-bearing age and male workers were reported. The dietitians preferred one set of common guidelines with specific action guides for each target group and wanted easier and more specific messages to be included in the new guidelines. It is suggested that the Life Cycle-based Dietary Guidelines for Koreans should be revised to reflect such dietitians’ needs.

The purpose of this study was to assess cross-generational effects of bisphenol A exposure in benthic copepods, Tigriopus west. Nauplii (<24 hours old) were exposed to graded concentrations of bisphenol A, and toxicity end-points such as survival, development, sex ratio, and fecundity were measured. F1 generations were grown under innoxious conditions, and similarly assessed. Significant differences were observed in development of nauplii and copepodites, between exposed and non-exposed copepods; however, there were no differences in survival of nauplii or copepodites, sex ratio, or brooding rate in parental generation. In contrast, in the F1 generation, there were significant differences between the control group and exposed group in survival and development of nauplii. Length, width, and biomass of parental and F1 generations were reduced in the exposed group compared to the control group. In addition, some deformities, such as swelling of the prosome, abnormally shaped egg sac, and dwarfism were observed after exposure to bisphenol A. So, our study demonstrates that a cross-generation toxicity test and monitoring of morphological deformities in harpacticoid copepods, can be useful for development of potential bioindicators for environmental monitoring, and assessment of chemical impact.

We investigated primary ecological characters, such as life cycle and morphology of the lawn cutworm, Spodoptera depravata (Lepidoptera: Noctuidae), which is one of the most economically damaging pests to grasses. For larval culture the turfgrass, Zoysia japonica, was provided as a feed source at 25℃ and 60±5% humidity. Development period of each stage was as follows: 4.11±0.19 days for eggs, 25.17±3.02 for larvae, 8.80±0.28 for pupae and 7.57±0.95 for adults. Larval stages continued to 7th instar and this result contrasts to pre-existing data, which indicate 6th instar in S. depravata. Developmental period of each instar of S. depravata ranged from the minimum of 2.1 days to the maximum of 4.81 days, with the 7th instar longest. Correlation analysis between body length and head capsule width of each instar showed a significant correlation between the two measures. Pupal colors were changed from the light brown and green right after pupation to dark brown as pupal cuticle hardens. Wing length of adults in both sexes was similar, but forewing of male had obvious outer line and eyespot with dark gray-brown background, whereas that of female had less obvious in these characters, with light gray-brown background. Pre-period of eggs deposition was 2 days, oviposition period was 4.6 days, average fecundity per female was about 419 eggs, and rate of hatching was about 83%.

흑백알락나비 (Hestina persimilis (Westwood, 1850))는 한반도의 평안남도 이남의 내륙지역에 넓게 분포하고, 국외의 경우 일본, 중국, 히말라야 일대에 서식하는 것으로 알려져 있다. 본 종에 대한 생활사 연구는 김과 서(2011)에 의해 월동유충, 종령, 번데기 등에 대한 일부 보고가 있을 뿐 자세한 생활사에 대한 기록은 전무하다. 본 연구를 통해 한국산 흑백알락나비의 생태적 습성 및 미성숙단계 (알, 유충, 번데기)의 형태적 특징 등 자세한 생활사 정보를 보고하고자 한다.

In the second half of the twentieth century, climate scientists have observed significant climate change events. Climate change scenarios characterized by increased temperature and precipitation in urban areas have resulted in disasters such as the urban heat island effect or street flooding. In response to these extreme climate scenarios, engineers have proposed permeable pavement technology. Permeable pavement is a type of pavement that allows water to flow through existing cavities into the pavement. The benefits of permeable pavement include reducing storm water runoff, reducing the heat island effect, and improving water quality, and reducing noise. In this study, a mechanistic-empirical analysis was performed to model the performance of permeable pavement in a subtropical climate with two variations of base and soil materials under both low and high traffic scenarios. The performance criteria for fatigue cracking and rutting were used to determine the service life of the permeable pavements. Furthermore, the estimated pavement performance was used to perform the life cycle analysis of the permeable pavements. Economic, environmental, and social sustainability aspects during the construction, maintenance, and operation periods were modelled for a 20 year analysis.

PURPOSES : So far, aged cement concrete pavement on express highways has been rehabilitated mainly with asphalt concrete inlay. However, potholes were the major problem, and they shortened the life of the inlay mainly owing to the poor drainage of water once it infiltrated the interface of the concrete and asphalt. The purpose of this study is to compare the performance and economic efficiency of asphalt overlay and inlayMETHODS: Overlay and inlay were compared through accelerated pavement testing, and a life-cycle cost analysis was conducted in this study using the CA4PRS program.RESULTS and CONCLUSIONS : It was found from accelerated pavement testing that the overlay exhibited reflective crack resistance that was more than twice as effective as that of inlay. The total cost (construction cost + user cost) within the analysis period (20 years) of the overlay was 37% lower than that of the inlay.

This research studies on the demand forecasting for service parts considering parts life cycle, that gets relatively less attentions in the field of forecasting. Our goal is to develop forecasting method robust across many situations, not necessarily optimal for a limited number of specific situations. For this purpose, we first extensively analyze the drawbacks of the existing forecasting methods, then we propose the new demand forecasting method by using these findings and reinforcement leaning technique. Using simulation experiments, we proved that the proposed forecasting method is better than the existing methods under various experimental environments.

본 연구는 해양에서 1차 소비자 단계인 윤충류 Brachionus plicatilis와 저서성 요각류 Tigriopus japonicus의 초기생활사에 미치는 탈인슬래그와 제강슬래그 추출액의 생태 영향을 평가하기 위하여 해양생태독성평가를 실시하였다. 슬래그 추출액에 대한 스크린 테스트 결과, 추출액의 pH는 높은 알칼리성(pH 8.89-12.16)이었으며, 숙성 전과 후 추출액에 대한 독성 반응은 실험생물에 따라 뚜렷하게 구분되었다. 숙성 전 슬래그의 경우, pH 비제어 시료에 대한 B. plicatilis 신생개체의 반수치사농도는 제강슬래그(63.8 %)가 탈인슬래그(20.8 %)보다 높은 것으로 나타났으며, T. japonicus 유생의 반수치사농도는 탈인슬래그와 제강슬래그에서 각각 35.3 %와 36.0 %로 비슷하였다. 그러나 pH를 제어한 경우, 숙성 전과 후 추출한 시료에 대한 T. japonicus 유생의 독성은 B. plicatilis 신생개체와는 다르게 노출물질 특성에 따라 뚜렷하게 구분되었다. 결론적으로 숙성 후 슬래그는 상대적으로 안정된 상태를 유지할 수 있으며, pH 비제어 환경조건 하에서도 반복 추출을 통해 해양환경에 미치는 영향이 적은 것으로 판단된다. 본 연구를 통해 슬래그와 같이 기계적으로 활성화 된 시료의 해양생태독성평가방법은 강우나 풍화로 인한 유해물질의 해양 유입을 차단할 수 있는 아이디어를 제공할 수 있을 것이다.

Since Taejongdae Resort Park’s designation as the first tourist area in 1969, a total of 230 domestic tourist areas have been designated, constructed, and operated thus far. Forty-seven years after the first tourist area designation, 38.8% of domestic tourist areas are now in a stage of stagnation/decline. As these declining domestic tourist areas only play their role as normal tourist areas during peak season, this study examined the causes of decline in tourist areas in general and of each tourist area in particular, so that the analysis could be used as basic data for the regeneration/revitalization of tourist areas. In order to understand the causes of decline, an index of cause of decline in tourist areas was drawn up. Data were collected based on this index, with tourist areas in the stagnation/decline stage as the target, which was drawn from previous research. Based on the results, factor analysis was conducted on both decline cause and discriminant analysis to understand the causes of decline in each tourist area. The results demonstrate that the diverse uses for tourists, sustainability, and preservation of tourism resources have a huge influence as internal factors, while the external capital investment and competitiveness of tourism resources have a huge influence as external factors. As this study only analyzed the quantitative index in accordance with physical characteristics, it is necessary to conduct additional research based on qualitative indices. In this case, this study could be used as basic data. This study is expected to be applied as basic research to seek solutions for each cause of stagnation/ decline in tourist areas, and also to establish measures to regenerate/revitalize those areas.

PURPOSES: Concrete pavement has been used in the construction of the Jungbu expressway in 1987. More than 60% of the pavement on the expressway is currently made of concrete, but most has been used far beyond their design life. Pavement life has been extended through routine maintenance or overlay. However, the structural capacity of the pavement has reached its limit, and extensive rehabilitation/reconstruction with long time traffic blocking should be considered. The three following issues on concrete rehabilitation/reconstruction will be discussed: (1) economic comparison of asphalt inlay and asphalt overlay, (2) economic comparison preventive overlay on a section which is currently good and routine overlay on the section which will be poor, and (3) economic analysis of early-strength concrete when it is used in concrete reconstruction. METHODS: First, various life cycle cost analysis tools were compared, and the proper tool for the extensive rehabilitation/reconstruction was selected. Second, a sensitivity analysis of the selected tool was performed to find the influential input variables, which should be carefully selected in the analysis. Third, three case studies, which can be issues in the rehabilitation/reconstruction of the expressway concrete pavement in Korea, were performed. RESULTS: Asphalt overlay without milling the deteriorated concrete showed 18~25% lower life cycle cost than the current asphalt inlay with milling. The good current preventive overlay on the section was economically justified within the scope of this study. The construction cost limit of the early strength concrete was suggested to be economical for 1, 3, and 7 days of construction alternative opening. CONCLUSIONS: CA4PRS was a viable tool for comparing various rehabilitation/reconstruction issue alternatives. Several concrete issues associated with the rehabilitation/reconstruction of the deteriorated concrete pavement were discussed as mentioned above.

PURPOSES : The authors set out to estimate the related carbon emissions, energy use, and costs of the national freeways and highways in Korea. To achieve this goal, a macro-level methodology for estimating those amounts by road type, road structure type, and road life cycle was developed. METHODS : The carbon emissions, energy use, and costs associated with roads vary according to the road type, road structure type, and road life cycle. Therefore, in this study, the road type, road structure type, and road life cycle were classified into two or three categories based on criteria determined by the authors. The unit amounts of carbon emissions and energy use per unit road length by classification were estimated using data gathered from actual road samples. The unit amounts of cost per unit road length by classification were acquired from the standard cost values provided in the 2013 road business manual. The total carbon emissions, energy use, and cost of the national freeways and highways were calculated by multiplying the road length by the corresponding unit amounts. RESULTS: The total carbon emissions, energy use, and costs associated with the national freeways and highways in Korea were estimated by applying the estimated unit amounts and the developed method. CONCLUSIONS: The developed method can be employed in the road planning and design stage when decision makers need to consider the impact of road construction from an environmental and economic point of view.

When designing Water Distribution System (WDS), determination of life cycle for WDS needs to be preceded. And designer should conduct comprehensive design including maintenance and management strategies based on the determined life cycle. However, there are only a few studies carried out until now, and criteria to determine life cycle of WDS are insufficient. Therefore, methodology to determine life cycle of WDS is introduced in this study by using Life Cycle Energy Analysis (LCEA). LCEA adapts energy as an environmental impact criterion and calculates all required energy through the whole life cycle. The model is build up based on the LCEA methodology and model itself can simulate the aging and breakage of pipes through the target life cycle. In addition the hydraulic analysis program EPANET2.0 is linked to developed model to analyze hydraulic factors. Developed model is applied to two WDSs which are A WDS and B WDS. Model runs for 1yr to maximum 100yr target life cycle for both WDSs to check the energy tendency as well as to determine optimal life cycle. Results show that 40yr and 54yr as optimal life cycle for each WDS, and tendency shows the effective energy is keep changing according to the target life cycle. Introduced methodology is expected to use as an alternative option for determining life cycle of WDS.

This study attempts to utilize the economic efficiency analysis results focused on the break-even point as an indicator for the decision making of commanders and staff. We suggested a method of determining economic life by utilizing logistics information system and commercial program Minitab with a focus on the equipment’s operational environment and performance data, whereas previously the equipment’s retirement period was simply determined by the current equipment prices and sustainable period.

The enterprise life cycle derived from the product life cycle consists of introduction, growth, maturity and decline. The enterprise tries to reach the growth stage early and stay at the maturity stage stably through expanding its businesses and investing for the new technology. The public enterprise is not different but its life cycle is more prone to be affected by the national development and policy. A typical example can be found in the case of the quasi market SOC public enterprise which spends massive amount of fund to provide social infrastructure. After the fulfillment of its mandated mission it is exposed to the pressure of a merger or a closure usually because large portion of the debt is directly linked to the national financial stability and credit ratings. This research is focused on the variables that influence the life cycle of the quasi market SOC public Enterprise for its future competitiveness is in connection with its normalization, advancement and rationalization. In this respect, categorical variables system centering on public characteristics and profitability drew eight categorical variables such as policy outcomes, public benefit, finance and business values etc.