The objective of this study was to compare the feeding effects of imported timothy hay, domestic Italian ryegrass silage (IRGS) and IRG dried by hot-air dry system (IRGHDS) under basic total mixed ration (bTMR) on rumination activity, milk production, and milk composition in lactating dairy cows. Eighteen Holstein dairy cows were divided into three groups: control (bTMR + imported timothy hay), treatment 1 (bTMR + IRGS) and treatment 2 (TMR + IRGHDS) groups. The study was conducted over a total period of 24 days, including a 10 days adaptation period and a 14 days main experimental period. The results indicate body weight was not significantly different between the three groups (p>0.05), and rumination time was significantly higher in the treatment 1 group compared with the control group (p<0.001). Milk fat, protein, and lactose were not significantly different between the three groups (p>0.05), however, somatic cell counts were significantly lower in the treatment 1 group compared with the control group (p<0.001). As a result of the economic feasibility analysis, it is expected that feeding TMR using IRGS and IRGHDS will increase profit by 402.8 won/day and 331.4 won/day per cow compared to imported timothy hay. Therefore, IRGS and IRGHDS can be used as substitutes for imported timothy hay in feeding lactating dairy cows.

We compared the reproductive performance, non-productive performance, and milk composition performance of two groups of lactating cows that were either rice straw or tall fescue. We also compared and analyzed these parameters after the first parturition during the breeding period. The calving interval, artificial insemination, and duration from calving to conception were longer in the rice straw group than in the tall fescue group. The 305-day and peak milk yields were significantly higher in the tall fescue group than in the rice straw group (p<0.01). Milk fat content was significantly higher in the tall fescue group than in the rice straw group (p<0.001), but milk protein content was the same between the feeding groups. The difference in raw milk sales income between rice straw and tall fescue groups tended to increase as the number of lactations increased, but there was no effect of reduced feed costs. Analysis of the milk production and raw milk sales income of the surveyed farms revealed that the average milk production per head was significantly (p<0.05) higher in the tall fescue group than in the rice straw group, and raw milk sales income showed a similar tendency. Overall, these results provide important details to be considered when selecting feed as a way to reduce milk production and heifer raising costs. However, there remains a need for future follow-up studies exploring the relationship between feed choice and the management of heifers.

목적 : 본 연구는 보조공학의 경제성 분석을 국내에 적용하기 위한 방안을 제시하고자, 보조공학의 경제적 및 사회경제적 가치와 측정 도구를 중점적으로 알아보고자 하였다. 연구방법 : 2013년 1월부터 2023년 9월까지, 국외 데이터베이스인 CINAHL, MEDLINE, SCOPUS, Web of science를 이용하여 보조기기 및 서비스의 경제성을 분석한 문헌을 검색하였다. 선정 및 배제 기준에 따라 총 16편의 논문을 최종 선정하였으며, 질적 수준을 평가하였다. 결과 : 경제성 분석에는 사회적, 개인적, 지불자 및 의료 관점이 고려되었으며, 이 중 사회적 관점이 가장 일반적이었다. 연구는 주로 미국과 유럽에서 수행되었으며, 아시아에서는 제한적이었다. 문헌의 질적 수준은 Markov 모델을 사용한 연 구에서 높았으며, ‘우수’ 또는 ‘보통’ 수준이 각각 13편, 3편이었다. 보조공학은 이동, 청각, 정보통신 그리고 기타로 분류 되었으며, 삶의 질을 고려한 문헌은 13편이었고, 주로 사용된 도구는 EQ-5D, HUI, SF-36과 WTP였다. 결론 : 본 연구는 국외 문헌 고찰을 통해 보조공학의 경제성 연구에 기초를 제공한다는 점에서 의의가 있으며, 향후 국내 에서 보조공학의 경제성 분석이 활발히 이루어지길 기대한다.

Wastewater management is increasingly emphasizing economic and environmental sustainability. Traditional methods in sewage treatment plants have significant implications for the environment and the economy due to power and chemical consumption, and sludge generation. To address these challenges, a study was conducted to develop the Intermittent Cycle Extended Aeration System (ICEAS). This approach was implemented as the primary technique in a full-scale wastewater treatment facility, utilizing key operational factors within the standard Sequencing Batch Reactor (SBR) process. The optimal operational approach, identified in this study, was put into practice at the research facility from January 2020 to December 2022. By implementing management strategies within the biological reactor, it was shown that maintaining and reducing chemical quantities, sludge generation, power consumption, and related costs could yield economic benefits. Moreover, adapting operations to influent characteristics and seasonal conditions allowed for efficient blower operation, reducing unnecessary electricity consumption and ensuring proper dissolved oxygen levels. Despite annual increases in influent flow rate and concentration, this study demonstrated the ability to maintain and reduce sludge production, electricity consumption, and chemical usage. Additionally, systematic responses to emergencies and abnormal situations significantly contributed to economic, technical, and environmental benefits.

As an advanced study on the method of calculating the target revenue water ratio of local waterworks through the leakage component analysis method proposed by Kim et al. (2022), this study developed a model to calculate the achievable revenue water ratio within the specified project cost, the required project cost to achieve the specified target revenue water ratio, and the economically appropriate target revenue water ratio level by considering the leakage reduction cost and leakage reduction benefit for each revenue water ratio improvement strategy, and conducted an applicability evaluation of the developed model using actual field data. The procedure for calculating the target revenue water ratio of local waterworks considering economics proposed in this study consists of three stages: physical data linkage model construction, leakage component analysis, and economic analysis, and the applicability was evaluated for Zone H with branch type and the Zone M network type. As a result of the application, it was calculated that approximately 32.5 billion won would be required to achieve the target revenue water ratio of 70% in the Zone H, and approximately KRW 10.5 billion would be required to achieve the target revenue water ratio of 75% in the Zone M. If the business scale of Zones H and M was corrected to 10,000 ㎥/day of water usage, the required project cost for a 1% improvement in the revenue water ratio of Zone H was calculated to be 0.7642 billion won and 0.4715 billion won for Zone M.

This study attempted to analyze the comparative advantage in terms of disaster safety costs in verifying the effectiveness and economic feasibility of the high-performance water-bulwark system in the pole tunnel, which was recently promoted as a part of the acceleration of vehicles. The tunnel to be analyzed was divided into a short tunnel(Anyang, Cheonggye) and a long tunnel(Suraksan, Sapaesan). As a result, it was analyzed that 25% of the improvement effect would occur if one lane was secured by applying the Water-Bulwark System. It was analyzed that this is because the time value cost, which accounts for a large proportion of the traffic congestion cost of short tunnels and pole tunnels, differs depending on the congestion time and traffic volume, not the length of the tunnel.

Laver aquaculture, which occupies a large proportion in the aquaculture industry in Korea, is still highly dependent on human labor. Therefore, it is necessary to study the development of an automatic system to improve the working environment and increase the efficiency of aquaculture production systems. The purpose of this study is to evaluate the economic feasibility of an improved system in a study for the loading-unloading and automatic weighing systems in laver aquaculture industry. Economic analysis of the developed unloading and automatic weighing system were implemented under various conditions to calculate more accurate benefits and costs. As a result of this study, the economic feasibility was found to be very high in the three models: net present value (NPV), benefit-cost ratio (B/C), internal rate of return (IRR). Moreover, the results of sensitivity analysis showed that the economical efficiency of the automatic loading, unloading, and weighing system in laver aquaculture was very high.

교량 인프라는 국민의 경제와 사회적 활동에 반드시 필요한 물리적 기반시설이고, 국민의 안전과 편의성에 직결되는 시설이므로 국민의 입장에서 편익을 고려해야 한다. 교량의 구성요소 중 바닥판은 교량 전체의 생애주기 동안 필연적으로 교체 시기가 도래하고 파손 등으로 인한 부분 교체도 빈번하게 이루어지고 있다. 바닥판 교체공사 시 거더와 바닥판을 합성하는 기 존 용접 전단연결재의 문제점을 해결하기 위한 볼트 접합 전단연결재(DY볼트)는 바닥판 철거 공정에서 파쇄를 최소화하고 교 체공사를 위한 전단연결재 재시공이 용이하여 공사 기간을 기존 대비 단축할 수 있는 것으로 분석되었다. 공사기간 중 도로차 단으로 인해 발생하는 도로이용자비용을 산출하여 기존 공법과 비교하는 방법으로 볼트 접합 전단연결재를 적용한 강합성 교량 의 경제성을 도로이용자(국민) 입장에서 분석하였다.

As the environmental impacts of fossil fuel energy sources increase, the South Korean government has tried to change non-environmental- friendly enery sources to environmental-friendly energy sources in order to mitigate environmental effects, which lead to global warming and air pollution. With both a limited budget and limited time, it is essential to accurately evaluate the economic and environmental effects of renewable energy projects for the efficient and effective operation of renewable energy plants. Although the traditional economic evaluation methods are not ideal for evaluating the economic impacts of renewable energy projects, they can still be used for this purpose. Renewable energy projects involve many risks due to various uncertainties. For this reason, this study utilizes a real option method, the Geske compound model, to evaluate the renewable energy projects on Jeju Island in terms of economic and environmental values. This study has developed an economic evaluation model based on the Geske compound model to investigate the influences of flexibility and uncertainty factors on the evaluation process. This study further conducts a sensitivity analysis to examine how two uncertainty factors (namely, investment cost and wind energy production) influence the economic and environmental value of renewable energy projects.

PURPOSES : The objective of this study was to evaluate the effectiveness of dust removal by dust removal vehicles by the measuring dust load and PM10 concentrations on the sidewalks of block pavements. METHODS : Field experiments were conducted to determine a dust removal method suitable for the sidewalk conditions, as identified through a literature review. Data collection was followed by the evaluation of the sidewalk dust load with removal vehicles and analysis of the PM10 content within a service road. Moreover, an economic analysis was conducted based on the social costs of dust reduction. RESULTS : When cleaning a sidewalk block by spraying water, the contaminants in small gaps in the block pavement could be reduced, providing a potential solution to void clogging. The dust on the surface of the sidewalk was suspended from a paved road with a high level of traffic volume. Using sidewalk dust removal vehicles with sweeping, spraying water, and inhalation reduced the dust load and PM10 contents by more than 2 and 0.07g/m2, respectively. CONCLUSIONS : According to the economic analysis of the development of dust removal vehicles for sidewalks, the cost-benefit analysis method shows an input effect of 0.4, but if the reduction amount of fine particles such as PM2.5, further experiments are necessary to address the atmospheric fine dust concentrations resulting from cleaning sidewalk block pavements.

Heavy bitumen scattered in the underground sedimentary layer is a kind of unconventional energy source, and by extracting it, a production well is excavated in the sedimentary layer and high-temperature and high-pressure steam is injected to reduce the viscosity of bitumen and recover it to the ground steam assisted method is applied. As a recovery method that uses the steam effect of the dilution effect of solvent injection, it is a recovery method that can increase thermal efficiency. In this study, the process system of the central processing facility(CPF) of the hybrid steam-solvent recovery method that injects solvent into the existing steam assisted method was analyzed, and the core facilities for each process were identified, and hybrid steam-solvent recovery compared to the existing steam assisted method. In the case of the method, it was evaluated that the amount of steam supply and all utility costs decreased according to the solvent injection.

고품질의 작물을 재배하기 위해 광은 필수적인 환경조건이 다. 겨울철에는 다른 계절에 비해 일사량이 저조하므로 보광 처리를 이용해 작물의 생육과 수확량을 증대시킬 수 있다. 본 연구는 약광기 동안 고추 온실재배를 위한 경제적인 보광 광 원을 선발하기 위해 수행되었다. 풋고추(Capsicum annuum ‘Super Cheongyang’)는 2019년 9월 5일에 정식하였다. 보광 처리는 2020년 1월 1일부터 2020년 3월 31일까지 수행되었 다. White LED(R:G:B = 5:3:2, W LED), RB LED(red:blue = 7:3, RB LED), 고압나트륨등(high pressure sodium lamp, HPS)을 광원으로 사용하였다. 무처리를 대조구로 사용하였 다. 고추의 초장, SPAD, 마디 수는 보광 광원에 따른 유의적인 차이가 없었다. 그러나 분지 수는 RB LED 광원에서 가장 많 았다. 또한 보광은 고추의 광합성을 증가시켰으며, 특히 RB LED에서 보광기간 동안 가장 높은 광합성률을 보였다. 또한 고추의 수확량은 보광처리에서 증가하였고, RB LED는 다른 광원에 비해 가장 높은 수확량을 보였다. 소비전력은 W LED 가 가장 높았고 HPS 조명이 가장 낮았다. 경제적인 측면에서 RB LED를 이용한 보광처리는 다른 광원에 비해 높은 경제성 을 가졌다. 결론적으로 이러한 결과는 고추 온실에서 약광기 동안 보광 광원으로 RB LED를 사용하는 것이 수확량과 경제 성을 향상시킬 수 있을 것으로 판단된다.

In this study, In order to apply the U-flanged truss hybrid beam to the actual construction site, the structural design of the basic module of the middle and low-rise neighborhood living facilities was performed according to the Korea Design Standard, and the construction cost and construction period were compared with the traditional reinforced concrete structure system. As a result of analyzing the construction cost for the basic module, if the U-flanged truss hybrid beam and D-Deck slab system are used, the construction cost can be reduced by 86% compared to the traditional reinforced concrete structure system. In addition, as a result of analyzing the construction period for a floor area of 1,000m2, using the U-flanged truss hybrid beam and D-Deck slab system can save 2.0days in construction period compared to the traditional reinforced concrete structure system. Therefore, the U-flange truss hybrid beam can secure sufficient economic feasibility compared to the existing reinforced concrete method in terms of cost reduction and shortening of construction period.

The Korean Air-Force aircraft maintenance depot paints the exterior of various aircraft, including high-tech fighters. Aircraft exterior painting is a maintenance process for long-term life management by preventing damage to the aircraft surface due to corrosion. The de-painting process is essential to ensure the quality of aircraft exterior paints. However, because the Korean Air-Force’s de-painting process is currently done with sanding or Plastic Media Blasting (PMB) method, it is exposed to harmful dust and harmful compounds and consumes a lot of manpower. This study compares the de-painting process currently applied by the ROK Air-Force and the more improved process of the US Air Force, and performs economic analysis for the introduction of advanced equipment. It aims to provide information that can determine the optimal time to introduce new facilities through Cost-Volume-Profit (CVP) analysis. As a result of the analysis, it was confirmed that the sanding method had the most economical efficiency up to 2 units per year, the PMB method from 3 to 21 units, and the laser method from 22 units or more. In addition, in a situation where the amount of de-painting work is expected to increase significantly due to the increase in fighters in future, BEP analysis was conducted on the expansion of the existing PMB method and the introduction of a new laser method. As a result of the analysis, it was confirmed that it is more economical to introduce the laser method when the amount of work exceeds the PMB work capacity(18 units per year). The paper would helpful to improve the productivity and quality of the Korean Air Force Aircraft maintenance depot through timely changes of facilities in the workplace in preparation for expansion.