• Environmental Engineering Research
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• 제12권5호
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• pp.238-243
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• 2007

The Fenton reaction, which refers to the reaction between ferrous ions and hydrogen peroxide to produce the OH radical, has not been widely applied to the disinfection of microorganisms despite being economic and environmentally friendly. Cho et al. have previously proposed the neutral photo ferrioxalate system as a solution to the problems posed by the Fenton reaction in acidic conditions, but this system still requires an external hydrogen peroxide supply. In the present study, we developed a simple disinfection technology using the photo or solar ferrioxalate reaction without the need for an external hydrogen peroxide supply. E. coli was employed as the indicating microorganism. The study results demonstrated the effectiveness of the photo ferrioxalate system in inactivating E. coli without any external hydrogen peroxide supply, as long as dissolved oxygen is supplied. Furthermore, the solar ferrioxalate system achieved faster inactivation of E. coli than an artificial light source at similar irradiance.

• 한국전기전자재료학회논문지
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• 제28권10호
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• pp.630-635
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• 2015

A vacuum Interrupter (VI), a core part that composes the breaking part of medium-voltage vacuum circuit breaker (VCB), has the excellent insulation performance and arc-extinguishing capability. $SF_6$ gas had been used for the external insulation of VIs since the dielectric strength of $SF_6$ gas is superior to that of other insulation gases. However, because of environmental problems related with global warming, a solid-insulated technology was recently researched. The functionally graded material (FGM), as changing spatially the distribution of the relative permittivity inside an insulator, can reduce the electric field stress at the specific region. Especially, the external insulation performance of the VI with the molded FGM insulator is greatly improved as compared with that of the existing VI or the VI with a new external shield. In this paper, the effectiveness of this FGM insulator is verified by the numerical simulation.

• 정보처리학회논문지A
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• 제15A권4호
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• pp.239-242
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• 2008

외부 메모리 계산 모델에서 스트링의 최대서픽스를 찾는 문제를 고려한다. 외부메모리 모델에서는 디스크와 내부메모리 사이의 디스크 입출력 횟수를 줄이는 알고리즘을 설계하는 것이 중요 사항이다. 길이가 N인 스트링은 N개의 서픽스를 가지는데, 이중에서 사전 순서에 따라 가장 큰 것을 최대 서픽스라 부른다. 최대서픽스를 구하는 것은 여러 스트링 문제를 해결하는 데 중요한 역할을 한다. 본 논문에서는 길이가 N인 스트링의 최대 서픽스를 구하는 외부메모리 알고리즘을 제시한다. 이 알고리즘은 네 개의 내부 메모리 블록을 사용하고 최대 4(N/L)번의 디스크 입출력을 한다. 여기서 L은 블록의 크기이다.

• 한국유통학회지:유통연구
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• 제1권1호
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• pp.83-107
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• 1996

The concern of external environment is growing up in the field of channel distribution. In the former channel distribution, the channel distribution environment is little bit unmoveable owing to a powerful manufacture control against poor distributor. Therefore intra-efficiency is channel member's core interest. The structure of channel governance, however, come to be changable because of the mature distributor power against manufacturer such as a Price Break, JIT of channel governance, and a serial of change. Accordingly, it is acceptable that the interest of external-environment of channel members' is more and more enlarged, and external-environment change in the channel distribution make the serious problems in intraorganizational system. Thus, it is meaningful that this study try to discover the consumer power as external environment factor and to find the best strategy to overcome this consumer power. Resource dependence theory, Transaction cost theory, Political Economic Approach, and Working partnership Approach are the theory foundation of the reasearch. Apparel franchise is a sample to analyse the hypothesis and correlation and multi-regression are a chief tools to estimate the hypothesis. Thus, the above results imply that a flexible governance is appropriate to consumer power, conflict is not intervening value between consumer power and channel governance, and the channel member's satisfaction can be confirmed in the flexible governance better than control governance.

• 문화기술의 융합
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• 제9권2호
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• pp.399-405
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• 2023

코로나블루 발생 원인을 분석해 우리 사회의 정신건강 증진 방안을 찾아보았다. 여성이 남성보다 코로나블루가 더 심했으며, 연령에 따른 차이는 없었다. 코로나19 이후 외부활동이 줄고, 가계경제는 어려워져 코로나블루가 늘었다. 늘어난 미디어이용량과 부정적인 미디어정보문제는 코로나블루를 증가시켰다. 온라인활동은 코로나블루에 영향을 주지 않았다. 미디어이용으로 증가한 사회문제관심은 미디어이용이 코로나블루에 영향을 주는 과정에서 부분매개효과를 갖고 있었다. 우울증을 줄이기 위해서는 개인의 외부활동을 늘리고, 여성과 경제적 약자의 사회 경제적인 여건을 더 개선하고, 미디어의 재난정보 품질을 높이고, 수용자는 미디어를 적정하게 이용해야 한다고 강조했다.

• 한국수학교육학회지시리즈A:수학교육
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• 제48권2호
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• pp.149-167
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• 2009

This study was aimed to examine problem-solving ability of fifth graders on two types of mathematical essay problems, and to analyze the process of mathematical justification in solving the essay problems. For this purpose, a total of 14 mathematical essay problems were developed, in which half of the items were single tasks and the other half were data-provided tasks. Sixteen students with higher academic achievements in mathematics and the Korean language were chosen, and were given to solve the mathematical essay problems individually. They then were asked to justify their solution methods in groups of 4 and to reach a consensus through negotiation among group members. Students were good at understanding the given single tasks but they often revealed lack of logical thinking and representation. They also tended to use everyday language rather than mathematical language in explaining their solution processes. Some students experienced difficulty in understanding the meaning of data in the essay problems. With regard to mathematical justification, students employed more internal justification by experience or mathematical logic than external justification by authority. Given this, this paper includes implications for teachers on how they need to teach mathematics in order to foster students' logical thinking and communication.

• 구강회복응용과학지
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• 제18권2호
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• pp.81-91
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• 2002

Dental implant systems have shown many post-surgical problems and One of the most frequent problem is screw loosening. To reduce screw loosening, a number of methods have been tried and recently fundamental modification of fixture-abutment connection structure was developed and used the most frequently. Former implant system structure, such as Br${\aa}$nemark, had external hex with the height of 0.7 mm and later, fixture with external hex of 1.0 mm height and internal hex structure were developed. In addition, the method of morse taper application was introduced to reduce screw loosening. In this study, the level of screw loosening of each implant systems was compared based on the vibration loosening measurement of abutment screw of each implant systems. Analysis of measured value was performed using 3 kinds of methods, (i) Percentage of average of initial 3 times loosening-torque value(initial loosening value) to tightening-torque of 30 Ncm, (ii) Percentage of loosening-torque value after 200 N strength loaded(experimental value) to initial loosening value and (iii) Percentage of experimental value to 30 Ncm of tightening-torque. Each result of analyses shows the value of initial loosening, loosening by repetitive load and final loosening level. The results of this study were as follows. (1) Percentage of initial loosening value to tightening-torque was increased in order of 0.7 mm external hex, 1.0 mm external hex, internal hex and internal taper and all values between each groups showed statistical significance (p<0.05). (2) Percentage of experimental value to initial loosening value was increased in order of internal hex, 0.7 mm external hex, 1.0 mm external hex and internal taper. Value of internal taper showed significant difference with that of 0.7 mm external hex and internal hex (p<0.05). (3) Percentage of experimental value to tightening torque was increased in order of 0.7 mm external hex, 1.0 mm external hex, internal hex and internal taper. Values of all groups showed statistical significance (p<0.05) except between the groups of 1.0 mm external hex and internal hex. Based on those results, there was no significant difference of loosening-torque by repetitive loading except internal taper. It is supposed that implant system with high resistant capability against initial loosening could be recommended for clinical use. In addition, in case of single implant restoration, 1.0 mm external hex or internal hex could be recommended rather than 0.7 mm external hex, and the use of internal taper would be the most useful way to reduce screw loosening.

• 경영과학
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• 제31권2호
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• pp.49-63
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• 2014

With the huge concerns on the inefficiency of public enterprises, particularly a significant amount of debt, an increasing number of studies have been carried out to analyze the levels of inefficiency and investigate the causes of that inefficiency. However, very limited range of analytical methodologies have been used in the efficiency analysis and moreover, the effects of external factors have been little addressed. This study explores the efficiency of urban railway corporations in Korea by utilizing a method of stochastic frontier analysis (SFA). In particular, the potential effects of external factors including residential and floating populations of a station were statistically analyzed. A total of seven Korean urban railway corporations were selected to compare each other in terms of operational efficiency. The results present three important findings. First, the Cobb-Douglas model was found to be more valid for SFA compared to the Translog model. Second, the efficiencies of urban railway corporations in Seoul and Busan are relatively high whereas those of Daejeon and Gwangju are very low in efficiency in the area of sales revenue. In an aspect of number of transport of passengers, Gwangju Metro also showed the lowest efficiency. Third, the external factors are significantly associated with the efficiency, indicating that the efficiencies of Daejeon Metro and Gwangju Metro would increase while the efficiency of Seoul Metro would decreases when the external variables are excluded in the efficiency analysis. The results provide several meaningful implications for managers of the urban railway corporations as well as policy makers who are attempting to resolve the inefficiency problems of public enterprises.

• Archives of Plastic Surgery
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• 제47권1호
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• pp.54-61
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• 2020

Background Conventional methods of external bleeding for congested fingertip replants exhibit notable problems, including uncontrollable bleeding and unpredictable survival of the replant. We have added a local injection of heparin calcium to the routine use of systemic heparinization for inducing external bleeding. We retrospectively examined patients who underwent external bleeding using our method. Methods Local subcutaneous injections of heparin calcium were made in 15 congested replants in addition to systemic heparinization. Each injection ranged from 500 to 5,000 U. The average duration of the injections was 4.1 days. Surgical outcomes were analyzed and compared with a control group of patients who underwent external bleeding without heparin calcium. Results The overall survival rate was 93.3%, which was higher than that of the control group (83.3%), but the difference was not statistically significant (P=0.569). The survival rate for subzones I and II by the Ishikawa subzone classification was 100%, whereas it was 87.5% in subzones III and IV. No statistically significant difference was observed. The rate of partial necrosis was 0% in subzones I and II, whereas it was significantly higher (66.7%) in subzones III and IV (P=0.015). The mean total blood loss via external bleeding was 588 g in 10 fingers. No patients required blood transfusion. Conclusions Congestion of a replanted fingertip can be successfully managed without blood transfusion by our method. Although complete relief from congestion in replants in subzones I and II is achievable, there is a higher risk of partial necrosis in subzones III and IV.

• 한국항해항만학회지
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• 제48권1호
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• pp.27-33
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• 2024

코로나 팬데믹 이후 컨테이너 터미널 내 혼잡도 증가에 따라 반출입 차량 작업 대기 및 체류시간이 급증하여 반출입 작업 비효율이 극심한 실정이다. 이에 항만 당국은 반출입예약시스템(Vehicle Booking System; VBS)을 구축하여 시범운영 중에 있으나 이해관계자 간 정보공유 문제 및 컨테이너 운송 주체의 미온적 참여 등으로 인해 개선효과가 뚜렷하지 않다. 따라서 본 연구에서는 반출입 차량의 작업 대기 및 체류시간 문제의 해결을 위한 기초자료로써, 딥러닝 기반의 반출입 차량 체류시간 예측 모형을 제시하였다. 실제 컨테이너 터미널의 반출입 운영 데이터를 통해 제시한 예측 모형을 실험하고 실제 데이터와 비교하여 예측 정확도를 검증한 결과 제시한 예측 모형이 높은 예측 정확도를 보이는 것을 확인하였다.