In this paper, a tidal power conversion system (PCS) using seawater level differences was presented.. To verify the presented PCS, an actual lab-scale tidal power generation system was constructed. The operation of the lab-scale PCS was first modeled mathematically and was analyzed through dynamic simulation and experimental tests.

금강 수계의 대형보가 2017년 6월부터 수문을 개방하기 시작하면서, 보의 상·하류에 다양한 모래톱이 드러나거나 새롭게 만들어지면서, 하천사주 지형의 생태계 가치를 파악하는 연구가 요구되었다. 본 연구는 세종보, 공주보, 백제보 구간을 대상으로, 광학 위성영상 공간분석을 통하여 보 건설 전, 보 건설 이후, 보 수문개방 후의 하천의 수변 서식처 지형 변화를 분석하였다. 위성영상은 물의 난반사로 인하여 수중공간을 구분할 수 없는 한계로 인하여, 수역은 단일 분류하고, 육상역인 하안사주와 하중도를 나지 부, 초본부, 목본부, 웅덩이 등으로 세분류하여 총 9개의 서식처로 분류하였다. 그리고 이러한 분류 기준을 적용하여 위성영상을 공간분석하여 단위서식처를 추출하고 그 면적비를 산출하였다. 보 건설 전·후를 비교한 결과, 보 건설 전에는 3개보 모두에서 전구간에서 사주가 폭넓게 발생하였지만, 보 건설 후에는 대부분의 사주면적이 급감하였으며, 특히 나지형 사주는 거의 사라졌다. 이러한 효과는 하류 공주보와 백제보로 갈수록 더욱 두드러진 경향을 보였다. 그러나, 수문개방 이후에는 다시 사주의 면적비는 증가하였고, 이 가운데 나지형 사주가 높은 비율을 차지하였다. 이는 상류 세종보에서 가장 효과가 크게 나타났다. 이러한 연구결과를 통해서 우리는 금강수계에서 보 건설에 의한 서식처 감소효과는 수계의 하류로 갈수록 크고, 보 개방에 따른 서식처 회복은 수계의 상류로 갈수록 효과가 크게 나타난 것을 발견하였다. 앞으로 서식처다양성과 생물다양성 간의 관계 연구를 통하여 조절하천의 자연성 회복과정을 체계적으로 규명할 수 있기를 기대한다.

본 연구는 탐진강 유역의 열린하구 강진만에서 하천과 해양 간의 성상별 탄소물질의 이동 특성을 파악하였다. 탐진강에서는 대부분의 탄소물질이 DOC 형태로 강하구로 유출되며, 하구로 오면서 조간대에 펼쳐진 갈대군락지에서 POC가 국지적으로 공급되고 있었다. 이에 반해 강진만에서는 DIC의 조성비가 탐진강에 비해 높게 나타났으며, 이러한 무기탄소는 주로 해양에서 공급되고 있는 것으로 나타났다. 이러한 결과를 종합해보면, 탐진강 열린하구는 하천과 바다의 영향이 상호 교차하는 지역으로 강에서는 유기탄소의 공급이 바다에서는 무기탄소의 공급이 주로 이루어져서, 탄소물질의 하구순환이 이루어지고 있음을 파악하였다. 이상과 같이 열린하구에서의 탄소조성 변화를 파악함으로써 하천과 하구, 해양 생태계 간의 환경특성에 따른 탄소공급원을 이해할 수 있었으며, 향후 보다 종합적인 연구를 위해 국내의 닫힌 하구와의 비교 자료로 활용될 수 있을 것이다.

본 연구는 대형 댐과 농업용 보가 공존하는 탐진강 유역을 대상으로 장흥다목적댐 건설 이후 탐진강의 서식처 지형변화를 정량적으로 분석하고, 이에 영향을 미치는 복합적인 환경요인 (대형 댐, 농업용 보, 조석, 하천정비)과의 인과관계를 유황변화, 하상재료, 항공사진 분석을 통해 파악하였다. 장흥댐 건설 후 유량변화를 분석한 결과, 유역에서 댐에 의한 유량 변화의 직접적인 영향 구간은 최대 지천이 합류되기 이전까지로 판단된다. 이 구간에서는 대규모 홍수는 발생하지 않았으며, 중소규모 홍수빈도 또한 절반 이하로 감소하는 등 하천의 유사이송 에너지가 감소하였다. 하상재료의 입도분포는 댐 직하류에서 모래가 급감하는 등 하상재료가 조립화되었지만, 금강천 합류 이후 하구까지는 다시 모래 비율이 높아지면서 하천의 자연성이 회복되고 있는 것으로 보여진다. 그렇지만, 지천 합류 이후의 이러한 유량 및 유사의 자연성 회복력은 본류 내 사주의 식생활착을 제어하기에는 부족해 보인다. 탐진강 하류에서 사주면적은 증가했지만 식생 피복율이 높은 원인은 지천에서 탐진강으로 공급된 유사가 장흥댐 건설에 따른 홍수 이송에너지의 감소와 더불어, 과밀화된 농업용 보에 의한 국지적인 지형변화, 그리고 감조역 구간에서 조석의 영향이 복합적으로 가져온 영향이라고 할 수 있다. 본 연구결과는 댐하류 서식처 지형의 자연성 회복을 위해서 유입지천의 중요성과 함께 본류의 환경 유량 복원과 유사 이송을 반영한 고도화된 수생태계 관리전략 수립의 필요성을 제시하고 있다.

In this paper, a new Co10Fe10Mn35Ni35Zn10 high entropy alloy (HEA) is identified as a strong candidate for the single face-centered cubic (FCC) structure screened using the upgraded TCFE2000 thermodynamic CALPHAD database. The Co10Fe10Mn35Ni35Zn10 HEA is fabricated using the mechanical (MA) procedure and pressure-less sintering method. The Co10Fe10Mn35Ni35Zn10 HEA, which consists of elements with a large difference in melting point and atomic size, is successfully fabricated using powder metallurgy techniques. The MA behavior, microstructure, and mechanical properties of the Co10Fe10Mn35Ni35Zn10 HEA are systematically studied to understand the MA behavior and develop advanced techniques for fabricating HEA products. After MA, a single FCC phase is found. After sintering at 900℃, the microstructure has an FCC single phase with an average grain size of 18 μm. Finally, the Co10Fe10Mn35Ni35Zn10 HEA has a compressive yield strength of 302 MPa.

Rivers continuously transport terrestrial organic carbon matter to the estuary and the ocean, and they play a critical role in productivity and biodiversity in the marine ecosystem as well as the global carbon cycle. The amount of terrestrial organic carbon transporting from the rivers to ocean is an essential piece of information, not only for the marine ecosystem management but also the carbon budget within catchment. However, this phenomenon is still not well understood. Most large rivers in Korea have a well-established national monitoring system of the river flow and the TOC (Total Organic Carbon) concentration from the mountain to the river mouth, which are fundamental for estimating the amount of the TOC flux. We estimated the flux of the total terrestrial organic carbon of five large rivers which flow out to the Yellow Sea, using the data of the national monitoring system (the monthly mean TOC concentration and the monthly runoff of river flow). We quantified the annual TOC flux of the five rivers, showing their results in the following order: the Han River (18.0×109 gC yr-1)>>Geum River (5.9×109 gC yr-1)>Yeongsan River (2.6×109 gC yr-1)>Sumjin River (2.0×109 gC yr-1)>>Tamjin River (0.2×109 gC yr-1). The amount of the Han River, which is the highest in the Korean rivers, corresponds to be 4% of the annual total TOC flux of in the Yellow River, and moreover, to be 0.6% of Yangtze River.

The biogeochemical information of riverine organic matter gives a detailed and integrated recording of natural and anthropogenic activity within a watershed. To investigate the changes in quality and quantity of organic carbon transporting from mountain to ocean via river channels, we estimated the concentrations of dissolved (DOC) and particulate organic carbon (POC), and then traced the source origin of POC using stable carbon isotopes ratio before and after summer rainfalls in the Tamjin River and Ganjin Bay, Korea. Along the small watershed, a total of 13 sites including headwaters, dam reservoir, river and estuary were established for the study. We found some interesting findings in the aspect of distribution of DOC/POC concentration changing their origin sources dynamically flowing downstream. In particular, the river channel transport downstream mainly DOC to river mouth, although upper dam reservoir increased POC concentration by phytoplankton production in summer. Whereas, in the river mouth and estuary, POC was dominated not only by local supply from nearby reed saltmarsh, but also by marine phytoplankton production, respectively. The findings can contribute to increasing the understanding of riverine organic carbon transport in upper large dam and lower open estuary system.

As a result of the increasingly serious air pollution worldwide, there are many social costs in the country. In general, there are legal measures to improve air quality such as investment projects, input of public funds, attraction of private capital, and regulation of air pollution prevention. In this study, we propose future legislative policies through the following analysis on the status of various researches in domestic and foreign countries for the improvement of air quality and related legal system. The domestic indoor air quality is getting better through ongoing management. From a legal perspective, The air quality law, such as indoor air quality law and environmental law, has been continuously revised to improve indoor air quality. However, contrary to the air quality law, indoor air quality management is carried out by various related departments under current law. Due to the different management facilities and management standards of each ministry, the effectiveness of relevant laws is deteriorated in organically managing multi-use facilities. This may lead to confusion and may be an impediment to the effective achievement of the institution's objectives. The pollutants of interior space are one of the main causes not only building materials, but also office equipment such as computers. however, The pollutants to be managed under the current legislation are mainly limited to building materials. In addition, the criteria set for each pollutant have a problem that it depends on the after-regulation standard that is made after the pollutant is released from the pollutant source. There is a need for systematic analysis and research to prevent adverse effects that may occur due to pollution sources through the prevention system. It is time to change the direction of regulation-oriented policies and to make policy changes that can improve air quality through systems such as emission trading system..

Among the information technology and automation that have rapidly developed in the manufacturing industries recently, tens of thousands of quality variables are estimated and categorized in database every day. The former existing statistical methods, or variable selection and interpretation by experts, place limits on proper judgment. Accordingly, various data mining methods, including decision tree analysis, have been developed in recent years. Cart and C5.0 are representative algorithms for decision tree analysis, but these algorithms have limits in defining the tolerance of continuous explanatory variables. Also, target variables are restricted by the information that indicates only the quality of the products like the rate of defective products. Therefore it is essential to develop an algorithm that improves upon Cart and C5.0 and allows access to new quality information such as loss cost. In this study, a new algorithm was developed not only to find the major variables which minimize the target variable, loss cost, but also to overcome the limits of Cart and C5.0. The new algorithm is one that defines tolerance of variables systematically by adopting 3 categories of the continuous explanatory variables. The characteristics of larger-the-better was presumed in the environment of programming R to compare the performance among the new algorithm and existing ones, and 10 simulations were performed with 1,000 data sets for each variable. The performance of the new algorithm was verified through a mean test of loss cost. As a result of the verification show, the new algorithm found that the tolerance of continuous explanatory variables lowered loss cost more than existing ones in the larger is better characteristics. In a conclusion, the new algorithm could be used to find the tolerance of continuous explanatory variables to minimize the loss in the process taking into account the loss cost of the products.1)

Harmonic structure materials are materials with a core–shell structure having a shell with a small grain size and a core with a relatively large grain size. They are in the spotlight because their mechanical properties reportedly feature strength similar to that of a sintered powder with a fine grain size and elongation similar to that of a sintered powder with a coarse grain size at the same time. In this study, the tensile properties, microstructure, and stretchflangeability of harmonic structure SUS304L made using powder metallurgy are investigated to check its suitability for automotive applications. The harmonic powders are made by mechanical milling and sintered using a spark plasma sintering method at 1173 K and a pressure of 50 MPa in a cylindrical die. The sintered powders of SUS304L having harmonic structure (harmonic SUS304L) exhibit excellent tensile properties compared with sintered powders of SUS304L having homogeneous microstructure. In addition, the harmonic SUS304L has excellent stretch-flangeability compared with commercial advanced high-strength steels (AHSSs) at a similar strength grade. Thus, the harmonic SUS304L is more suitable for automotive applications than conventional AHSSs because it exhibits both excellent tensile properties and stretch-flangeability.

In this study, we analyzed the factors affecting the concentration of airborne asbestos fiber in the indoor and outdoor environment of a slate roofing house, and performed a health risk assessment of residents living in houses with slate roofs. Sampling was conducted at ten houses with slate roofs on 3 different days under different weather conditions. A high flow rate pump was used for sampling. The specimen was assessed using a phase-contrast microscope. The degree of risk of exposure to asbestos was assessed using EPA’s carcinogen risk assessment method. Asbestos fiber concentrations for slate roofing houses were 2.43 fiber/L inside and 2.46 fiber/L outside, respectively. The correlation between the indoor and outdoor asbestos fiber concentration was 0.486. But on both sides, the asbestos fiber concentrations did not exceed the standard (10 fiber/L) for ambient air in Korea. The factors affecting the concentration of asbestos fiber were year of construction (p<0.05), total roof area (p<0.05) and average wind velocity (p<0.01). According to EPA’s ELCR (Excess Lifetime Cancer Risk) on air pollution substances, a level of 1.0E-04~1.0E-06 should be maintained. However, the ELCR level of 6 out of 10 houses was over 1.0E-04. Therefore, a risk management plan for residents of slate roofing houses must be prepared immediately.

본 연구에서는 볼텍스 세퍼레이터 내부의 밀폐된 영역 내에서 발생하는 회전에 의한 입자상 물질과 유체의 분리 특성 파악을 위하여 전산유체역학을 이용한 수치해석을 수행하였다. 볼텍스 세퍼레이터는 접선방향 운동량으로 인해 회전유동이 발생하여 원심력과 중력으로 인한 입자상 물질과 유체의 분리가 이루어지므로 비정상 상태의 복잡한 흐름을 갖는다. 본 연구에서는 유한체적법 기반의 3차원 점성 유동장의 비정상 해석을 수행하였으며 이상유동의 해석을 위하여 오일러-오일러 모델을 이용하였다. 효율적인 설계를 위하여 세 가지 형태의 볼텍스 세퍼레이터 내부 구조에 대한 분석을 수행하였으며, 입자상 체적비, 입자 직경의 변화에 따른 분리 효율을 비교하였다. 또한 전산해석을 통하여 얻어진 분리성능을 확인하였으며 실험을 통한 검증을 수행하였다.

기후변화 등으로 인해 폭풍해일의 피해가 증대하고 있어, 재현기간에 기초한 폭풍해일고의 추정은 새로운 연안 구조물의 설 계 및 개발 관점뿐만 아니라 기존 구조물의 안정성을 평가하는데 중요하다. 현재 우리나라의 설계해면은 과거 태풍을 이용한 극치 분 석을 이용하여 추정되지만, 이 경우 자료의 부족으로 재현기간이 큰 경우 오차의 원인이 될 수 있으며, 추계학적 접근은 하나의 대안 이 될 수 있다. 본 연구에서는 폭풍해일에 취약한 경기만 지역의 폭풍 해일고 추정을 위해 결정론적 수치 모형인 SLOSH 모형과 가상 태풍을 위한 몬테카를로 시뮬레이션의 결합을 통하여 추계학적 접근 방법을 제시하였다. 모멘트법에 의해 결정된 파라메터를 이용하 여 Weibull 분포를 통해 추계학적 해일고가 추정되었으며, 제시된 폭풍 해일고는 연안 지역 구조물 설계를 위한 대안이 될 수 있다.

Many enterprises have been adopting management systems good enough for them and operating the schemes to have competitive edge better than their competitor. One of the finest systems that most companies have been selecting is ISO 14001. ISO 14001, environment management system, is widely known as advancing internal efficiency and productivity in the various industries. As a result, the number of companies that have adopted ISO 14001’s certification have been increasing continuously year by year since ISO 14000 standard was called in 1994s from ISO 18000 standard that originally used. The purpose of this study is to present that ISO 14001’s requirement execution influences on management performance in the small manufacturer. In order to carry out this research, we obtained 96 survey sheets and inspected ten assumptions based on the reliability, validity of the questionnaires. The results of regression analysis are summarized as follows; First, the three factors of ISO 14001 requirement, plan, implementation and operation and management consideration, have an important effect on the operational performance. Second, the three elements of ISO 14001 requirement, environment policy, implementation and operation and management consideration, affect to the financial performance significantly. Based on the results, it is sure that the companies that execute the factors of implementation and operation and management policy have a good performance to achieve operational and financial performance so that it is important to clarify the member’s role, authority and follow the procedure by a company’s process. Also, the truth shows CEO’s continuous will and periodical review of ISO 14001 influence on management performance as well.

The purpose of this study is to present that the entrepreneurial orientation affects to management performance in the small manufacturer. In order to carry out this research, we obtained 171 survey sheets and inspected seven assumptions based on the reliability, validity of the questionnaires. The results of regression analysis are summarized as follows; First, the factor of entrepreneurial orientation, innovative-ness, influences on the technical innovation performance and financial performance significantly. Second, the element of entrepreneurial orientation, proactive-ness, has an important effect on the technical innovation performance and financial performance. Finally, the requisite of entrepreneurial orientation, risk taking, affects to the technical innovation performance significantly, but not the financial performance. Based on the results, the companies that achieve the technical innovation and financial performance have an atmosphere to encourage to perform the research and development works and find out innovative ideas and improvement points in processes. However, the entrepreneur is required to take careful judgement for determining the uncertain circumstance.

Process Capability Index (PCI) is useful Statistical Process Control (SPC) tool that is measure of process diagnostic and assessment tools widely use in industrial field. It has advantage of easy to calculate and easy to use in the field. Cp and Cpk are traditional PCIs. These are only considers of process variation. These are not given information about the characteristic value does not match the target value of the process. Studies of this process capability index by many scholars actively for supplement of its disadvantage. These studies to evaluate the capability of situation of various field has presented a new process capability index. Cpm is considers both the process variation and the process deviation from target value. And Cpm + is considers economic loss for the process deviation from target value. In this paper development of new process capability index that is Taguchi's quadratic loss function by applying the expected loss. And check the correlation between existing traditional process capability index (Cpk) and new one. Finally, we propose the criteria for classification about developed process capability index.

Process Capability Index(PCI) is useful Statistical Process Control(SPC) tool that is measure of process diagnostic and assessment tools widely use in industrial field. It has advantage of easy to calculate and easy to use in the field. Cp and Cpk are traditional PCIs. These are only considers of process variation. These are not given information about the characteristic value does not match the target value of the process. Studies of this process capability index by many scholars actively for supplement of its disadvantage. These studies to evaluate the capability of situation of various field has presented a new process capability index. Cpm is considers both the process variation and the process deviation from target value. And Cpm+ is considers economic loss for the process deviation from target value. In this paper development of new process capability index that is Taguchi's quadratic loss function by applying the expected loss. And check the correlation between existing traditional process capability index(Cpk) and new one. Finally, we propose the criteria for classification about developed process capability index.

This study is to identify the present condition and level of human resource administration in domestic profit and non-profit organizations, and to investigate on the relation between human resource management and management performance in enterprise. This