• 한국재료학회지
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• 제22권11호
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• pp.620-625
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• 2012

A general synthetic method to make $Fe_3O_{4-{\delta}}$ (activated magnetite) is the reduction of $Fe_3O_4$ by $H_2$ atmosphere. However, this process has an explosion risk. Therefore, we studied the process of synthesis of $Fe_3O_{4-{\delta}}$ depending on heat-treatment conditions using $FeC_2O_4{\cdot}2H_2O$ in Ar atmosphere. The thermal decomposition characteristics of $FeC_2O_4{\cdot}2H_2O$ and the ${\delta}$-value of $Fe_3O_{4-{\delta}}$ were analyzed with TG/DTA in Ar atmosphere. ${\beta}-FeC_2O_4{\cdot}2H_2O$ was synthesized by precipitation method using $FeSO_4{\cdot}7H_2O$ and $(NH_4)_2C_2O_4{\cdot}H_2O$. The concentration of the solution was 0.1 M and the equivalent ratio was 1.0. ${\beta}-FeC_2O_4{\cdot}2H_2O$ was decomposed to $H_2O$ and $FeC_2O$4 from $150^{\circ}C$ to $200^{\circ}C$. $FeC_2O4$ was decomposed to CO, $CO_2$, and $Fe_3O_4$ from $200^{\circ}C$ to $250^{\circ}C$. Single phase $Fe_3O_4$ was formed by the decomposition of ${\beta}-FeC_2O_4{\cdot}2H_2O$ in Ar atmosphere. However, $Fe_3C$, Fe and $Fe_4N$ were formed as minor phases when ${\beta}-FeC_2O_4{\cdot}2H_2O$ was decomposed in $N_2$ atmosphere. Then, $Fe_3O_4$ was reduced to $Fe_3O_{4-{\delta}}$ by decomposion of CO. The reduction of $Fe_3O_4$ to $Fe_3O_{4-{\delta}}$ progressed from $320^{\circ}C$ to $400^{\circ}C$; the reaction was exothermic. The degree of exothermal reaction was varied with heat treatment temperature, heating rate, Ar flow rate, and holding time. The ${\delta}$-value of $Fe_3O_{4-{\delta}}$ was greatly influenced by the heat treatment temperature and the heating rate. However, Ar flow rate and holding time had a minor effect on ${\delta}$-value.

• 한국농공학회지
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• 제37권3_4호
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• pp.34-47
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• 1995

It is experienced fact as a regular annual event that the structure to he designed on unreasonable flood for the agricultural structures including reservoirs have been brought not only loss of lives, but also enormous property damage. For the solution of this problem at issue, this study was conducted to develop an optimal runoff hydrograph model by comparison of the peak flows and time to peak between observed and simulated flows derived by linear time-invariant and linear time-variant models under the condition of having a short duration of heavy rainfall with uniform rainfall intensity at nine small watersheds which are within the range of 55.9 to 140.7 square kilometers in area in Han, Geum, Nagdong and Yeongsan Rivers. The results obtained through this study can be summarized as follows. 1. Storage constants and Gamma function arguments were calculated within the range of 1.2 to 6.42 and of 1.28 to 8.05 respectively by the moment method as the parameters for the analysis of runoff hydrograph based on linear time-invariant model. 2. Parameters for both linear time-invariant and linear time-variant models were calibrated with nine gaged watershed data, using a trial and error method. The resulting parameters including Gamma function argument, N and storage constant, K for linear time-invariant model were related statistically to watershed characteristic variables such as area, slope, length of main stream and the centroid length of the basin. 3. Average relative errors of the simulated peak discharge of calibrated runoff hydrographs by using linear time-variant and linear time-invariant models were shown to be 0.75 and 5.42 percent respectively to the peak of observed runoff hydrographs. Correlation coefficients for the statistical analysis in the same condition were shown to be 0.999 and 0.978 with a high significance respectively. Therefore, it can be concluded that the accuracy of a linear time-variant model is approaching more closely to the observed runoff hydrograph than that of a linear time-invariant model in the applied watersheds. 4. Average relative errors of the time to peak of calibrated runoff hydrographs by using linear time-variant and linear time-invariant models were shown to be 16.44 and 19.89 percent respectively to the time to peak of observed runoff hydrographs. Correlation coefficients in the same condition were also shown to be 0.999 and 0.886 with a high significance respectively. 5. It can be seen that the shape of simulated hydrograph based on a linear time- variant model is getting closer to the observed runoff hydrograph than that of a linear time-invariant model in the applied watersheds. 6. Two different models were verified with different rainfall-runoff events from data for the calibration by relative error and correlation analysis. Consequently, it can be generally concluded that verification results for the peak discharge and time to peak of simulated runoff hydrographs were in good agreement with those of calibrated runoff hydrographs.

• 유통과학연구
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• 제13권12호
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• pp.53-63
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• 2015

Purpose - Recently, creating shared value (CSV) has attracted attention through plan sustainability and the growth of corporate management. Porter and Kramer (2011) defined the core concept of CSV as social value, economic profits, improvements in the economic social condition, and reinforcing competitiveness. The purpose of CSV, which is to pursue economic profits through a social solution to the problem, agrees with managing the objective of a social enterprise that prioritizes the pursuit of profits through the realization of a social purpose. Today, CSV studies focus on CSR and sustainability and reinforce competitiveness. However, few studies focused on the social economy. Precedent studies examined CSV using a company example, and few studies exist from the perspective of consumers and the point of view of a market society. Research design, data, and methodology - Therefore, this study examines CSV in comparison to a background of the social economy. This study also investigates and analyzes the concept of social value from the point of view of consumers, social problems, consumption value, corporate value, and the influence of consumers. This article develops three hypotheses. Hypothesis 1 investigates the correlation with social innovation that consumers thought as being necessary for social innovation by a company. Hypothesis 2 is used to confirm the influence of consumers in CSV. Therefore, this article investigates the influence of consumers on consumption action for companies that are indifferent to social problems. Hypothesis 3 is used to verify the correlation between the value that consumers demand through consumption and the corporate value that companies pursue other than profits. The three hypotheses were adopted and met the standard for suitability. Results - The importance of the CSV study from the consumer perspective was confirmed using the influence of consumers on CSV. Because the objective of company activities is either the consumer or the market, the influence that extends to interactions between the company and consumers to ensure the success of a business is significant. Regarding the CSV study, because it was an initial study, various approaches are subsequently developed. However, conceptual and practical case studies on CSV currently exist that may be used to verify the factors that comprise CSV. Therefore, the company example may enable verification of the factors that influence the composition of CSV through identification from the consumer perspective. In addition, studying CSV as an action result (of consumer satisfaction, of a company's profits and competitiveness, and of society's cancellation of a social problem) may enable the realization of a practice paradigm as opposed to simply thought and faith. Conclusions - First, this study confirms the social value of a business through the feasible and common pursuit of consumers by corporations. Second, customer influence accounts for an important part of CSV. Third, shared value commonly provides a necessary advantage to consumers, corporates, and society, and contributes to the economy and healthy social development. Fourth, corporates can conduct a business, generate profits, and realize value through improvements in social problems and by addressing their competitive strengths and weaknesses.

• 유통과학연구
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• 제12권6호
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• pp.41-48
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• 2014

Purpose - This study aims to investigate a solution to reduce the negative reactions arising from the performance of duties or the job distress of workers in the service industry, because human resource statistics regarding workers in the service sector have been unreported, while concerns regarding exposure to emotional exertion and poor working conditions have been continuously increasing. Research design, data, and methodology - This study specifically focused on workers in highway service areas. It differs from previous studies because it involves the perspective of the person-organization fit and regards workers' cognition of leaders through the psychological distance toward the leader and the contact frequency between workers and leaders within the framework of the leader-individual fit. Moreover, this study highlights the role of the self-leadership of workers as an important factor that becomes manifested in the individual-level fit to the organization. Hence, this study investigates whether the positive role of the above factors, in turn, could reduce job distress. Workers from highway service areas in Gyeonggi-do province provided data; 141 valid questionnaires are collected. SPSS 19.0 and AMOS 19.0 were used to test the reliability and validity of constructs. Simple regression, multiple regression, and 3 step mediation tests were used to test the hypotheses after the correlation tests. Results - Results indicated that leader-member contact frequency and psychological distance have negative effects on job distress but positive effects on self-leadership. A mediation test revealed that self-leadership, in the relationships between contact frequency and job distress and between psychological distance and job distress, resulted in partial mediation and full mediation, respectively. Conclusions - The result can be understood through two different possible explanations. First, service area workers generally possess a positive perspective toward their leaders. This can be interpreted to mean that increased contact frequency and psychological distance would be considered as supports from the leader, rather than intrusive controls or management schemes. Therefore, the management in highway service areas should invest efforts in increasing contact frequency as well as maximizing psychological similarities by adopting the viewpoints of workers in terms of moral and ethical management, to reduce the workers' job distress. The results relating to self-leadership also indicate that increased contact frequency must be accompanied by intentions for the effective promotion of workers' self-leadership. It also signifies the necessity of a strategic approach by leaders to induce workers to perceive "in-group"ness as suggested both by the similarity-attraction theory and by the social identity theory. In addition, the results of the mediation test of self-leadership indicate that because workers' self-leadership activates upon increased contact frequency by the leader, it should not be a means of control and should not be utilized only from the perspective of management. It is also suggested that strategies such as transfer of authority could have a positive effect in promoting the expansion of self-influence from workers.

• 유통과학연구
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• 제16권8호
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• pp.63-68
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• 2018

Purpose - Lettuce (Lactuca sativ L.) is one of the economically important vegetable crops, which worldwide market value is over 100 billion U.S. dollar. In Korea, about 89.7 kilo ton of lettuce was produced in 3400ha in 2016, recoded as No. 1 vegetable crop in domestic green house production. However, recently, domestic lettuce production and cultivation areas are all getting decreased. Thus, novel approaches are needed to be implemented to revive the production. Research design, data and methodology - In this review paper, we first prioritized the end-user traits which are imperative to positively stimulate the domestic lettuce market and discussed relevant genomics strategies. Especially, we assessed a possibility whether school meal program would be a potential niche market. Results - The genomics technologies, which become widely applied in the crop biotechnology since 2008 when next generation sequencing method was developed, may be a good solution in the crop improvement, efficiently gathering valuable information of agriculturally useful traits. Significantly, in lettuce, the high quality whole genome sequence, based on Lactuca sativa cv. Salinas, is publically available and this genomics platform, thus, would be implemented in lettuce breeding program to innovate relevant end-user traits both for the farmers and customers, including the disease resistance to the Fusarium wilt, productivity under hot weather conditions, various nutritional qualities and so forth. These improvements will boost domestic lettuce industries in the near future. Conclusions - Due to the nutritional distinctions comparing to the western style lettuces, domestic leaf lettuces could be one of the important vegetables in the school meal programs. To make it happen, we would better devise diverse recipes to make a salad with it, instead of only using as a wrap vegetable. Meanwhile, novel lettuce varieties need to be developed, which are favorable to the students and also easy to be handled with while processing. Overall, to achieve international competence in the lettuce industries, we need to create elite lettuce varieties that satisfies domestic farmers as well as customers, suitable to various niche markets, such as school meal program. Thus, efficient breeding programs using genomics approaches should be established in advance and careful monitoring on the preference of the related customers for a niche market be continued persistently.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제11권3호
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• pp.224-234
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• 2005

인터넷의 성장과 더불어 네트워크 관련 기술의 발전으로 인해 인터넷의 사용량 및 사용인구가 폭발적으로 증가하고 있는 추세이다. 이런 추세에 대학의 전산망도 노드 수의 급속한 증가와 다양한 서비스로 인해 네트워크에 대한 트래픽이 증가하고 있다. 이에 반해 사용자에 대한 서비스 품질은 낮아지고 있는 실정이다. 이에 따라, 대학 네트워크에 대한 네트워크 관리, 네트워크 설계 및 증설, 요금정책 등에 사용될 수 있는 매우 핵심적인 문제점이 나타나고 있다 이러한 문제점을 효율적으로 분석하여 관리를 하기 위해서는 많은 기술인력과 장비 및 예산이 소요된다. 그러나, 규모가 적은 대학 네트워크는 인력 부족과 네트워크 환경에 대한 지속적인 투자로 인해 실행하기 어려운 부분이다. 이러한 네트워크에 대한 투자 비용을 감소하고 최적화된 환경을 조성하기 위해서는 구성변경 및 장비의 대체나 용량계획에 대한 성능분석이 필수적이다. 따라서, 본 논문에서는 네트워크 관리와 분석을 위하석 관리 및 분석대상과 관련된 모든 항목을 프레임워크 기반 성능관리 도구를 이용하였다. 주요 연구방법으로는 세부 항목별로 현황 데이터를 수집, 가공, 분석하여 각 항목을 상세하게 분석하여 문제점에 대한 해결책을 제시하였다. 이러한 결과 네트워크, 서버, 애플리케이션 관리를 체계적으로 관리할 수 있었으며, 장애 및 성능저하 둥으로 업무영역에 미치는 영향을 파악하고 예방에 효과적으로 대응할 수 있었다. 또한, 과학적이고 체계적인 분석을 통해 전체 시스템의 운영관리비용을 최적화하여 관리의 효율성을 높여주었다.

• 융합정보논문지
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• 제10권7호
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• pp.153-159
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• 2020

본 연구에서는 실제 하수관로 내 흐름상태를 파악하기 위하여, 건기동안 처리구역 최상부에 위치한 관로의 수위, 유속, 유량의 값을 실제 측정하여 추정된 하수의 전단응력을 조사하였다. 수세분뇨 및 토사를 모사하기 위해 점착성 및 비점착성 고형물(두부와 모래)을 따로 또 함께 투입한 후 흐름의 상태를 촬영하였는데, 본 실험대상관로에서는 큰 방해없이 침전물이 하수와 함께 씻겨 내려가는 것을 관찰하였다. 경사가 0.00319인 관로에서 주중 하수의 최소전단응력을 초과하는 빈도는 0이었고 0.00603의 기울기의 경우 10회였다. 현장조사기간 중 최소전단력을 초과하는 이벤트는 1회 발생하여 하수도에서 악취가 증가될 가능성을 시사하였다. 경사가 가파른 관로의 최대전단응력은 2.9~3.1N/㎡이었지만, 완만한 경사에서는 1.6~1.7 N/㎡으로 감소하였다. 강우시 합류식 관로로 유입될 수 있는 비응집성 입자를 포함한 하수는 최소전단응력 기준 이하로 유지되는 시간 간격이 주중에 비해 주말동안 증가하였다. 설계기준에 따라 설계된 본 실험대상 관로에서는 수세분뇨가 직투입되어도 관로내 침전물이 오래 퇴적상태로 머물지 않고 하수와 함께 흘러갈 수 있음을 확인할 수 있었다.

• 한국인터넷방송통신학회논문지
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• 제16권2호
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• pp.189-199
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• 2016

현재의 국가기술자격제도가 당면한 여러 가지 현안에 대해서 원인과 개선사항을 다루고자 하였다. 국가기술자격의 문제점을 분석하기 위하여 국가기술자격의 주요현황에 대해 조사하였다. 취업 시 가산점 종목과 의무고용 형 법령이 적용되는 종목들의 취득분포를 조사한 결과 우대사항과 매우 밀접한 관계가 있음을 확인하였다. 지금까지 제기되었던 국가기술자격 제도에 대한 개선요소들을 엄선하여 AHP 분석을 하였다. AHP 분석을 통하여 가장 시급하게 개선되어야 할 요소들의 우선순위를 결정하였다. AHP 실증분석 결과를 기반으로 우선순위가 높은 항목 위주로 국가기술자격에 대한 개선사항을 제시하였다. 첫째로 전문가들의 의견을 수렴하여 국가기술자격 문제의 변별력을 높이기 위한 방안을 제시하였다. 두 번째로 현재의 우대정책이 의무고용 형 자격을 확대하는 방향으로 진행되어야 한다는 의견을 제시하였다. 세 번째로 기술자 경력수첩제도의 문제점을 개선하기 위한 의견 두 가지를 제시하였다. 기타 제안사항으로, 유사종목의 통폐합을 비롯한 3가지 개선방안을 제시하였다. 본 논문의 연구 결과가 국가기술자격의 미래설계에 유용한 데이터로 작용할 수 있을 것으로 기대된다.

• 한국결정성장학회지
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• 제27권3호
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• pp.143-147
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• 2017

PVT법으로 성장된 AlN 단결정의 표면 특성 및 결정성을 신뢰성 있게 평가하기 위해 $KOH/H_2O_2$ 혼합액을 이용한 화학적 습식 에칭을 통하여 AlN 단결정의 결함을 분석하였고, 고온 어닐링 공정을 통해 단결정의 결정성 변화를 관찰하였다. $300^{\circ}C$ 이상의 고온에서 강 염기성의 etchant를 사용하는 기존 에칭 방법에서는 재료의 결정성에 따라 쉽게 over etching이 일어난다. Over etching이 일어날 경우 면적당 정확한 에치 핏의 개수를 알 수 없기 때문에 전위 밀도의 신뢰성이 매우 떨어진다. 따라서 이러한 단점을 보완하기 위해 KOH 수용액에 $H_2O_2$를 산화제로 사용하여 $100^{\circ}C$ 이하의 저온에서 에칭을 성공하였으며, 주사전자현미경(SEM, scanning electron microscope)을 통해 에치 핏을 관찰하여 최적 에칭 조건 및 전위 밀도를 확인할 수 있었다. 또한, 성장된 AlN 단결정에 고온 어닐링 공정을 적용한 후, DC-XRD(double crystal X-ray diffraction)를 이용하여 결정성을 평가한 결과, 고온 어닐링 공정 후 FWHM(full with at half maximum) 값이 급격히 감소되는 것을 확인하였으며 이에 대한 메커니즘을 분석하였다.

• 대한전자공학회논문지SD
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• 제40권5호
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• pp.345-353
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• 2003

네트워크 프로세서를 설계하거나, 라우터와 같은 장비를 구현할 때, 가장 성능을 좌우하는 부분이 IP lookup 동작이라 할 수 있다. 어드레스 체계가 간단해지면 IP lookup 동작이 단순화될 수 있어 성능이 좋아질 수 있지만, 네트워크 사용자의 증가로 인하여 효율적인 어드레스 관리가 필요하게 됨으로써 어드레스 체계는 복잡해질 수밖에 없는 상황이 되었다. 따라서 IPv4나 IPv6에서나 마찬가지로 어드레스 체계의 복잡성에 의해 IP lookup 동작이 어렵고 시간이 오래 걸리는 작업이 되는 것은 받아들일 수밖에 없는 현실이 되었다 소프트웨어적으로나 하드웨어적으로 IP lookup 성능을 향상시킬 수 있는 방안들이 연구되어 왔지만, 아직까지 해결책이라고 단정지을 수 있을 만한 연구결과는 나오지 않고 있다. 소프트웨어적인 방법은 메모리 사용량을 줄일 수 있지만 IP lookup시 검색이 느리고, 하드웨어적인 방법은 빠르지만 하드웨어 오버헤드와 메모리 사용량이 크다는 문제가 있다 이에 이 논문은 지금까지의 IP lookup 동작을 향상시키기 위한 연구들을 정리해 보고, 이들의 장단점을 파악하도록 한다. 또한, 대표적인 소프트웨어와 하드웨어 구조를 혼합하고, 병렬적으로 구성하여 성능을 높일 수 있는 새로운 혼합 구조를 제안한다. 성능 평가 결과는 제안된 구조가 lookup 속도를 향상시키면서도, 메모리 사용량도 줄일 수 있다는 것을 보여준다.