• 유통과학연구
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• 제10권7호
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• pp.5-11
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• 2012

The core objective of this research article is to investigate different challenges and opportunities in management as well as start-ups of small businesses in India. The prudence behind this research is to examine various problems in front of the small businesses and to offer vital support and cooperation to overcome those with the support of concerned institutions through consultancy and training programs. The researchers have an intention to make available the research results to the governmental agencies, concerned small business institutions and also to the educational institutions which are continually design plans, programs, policies and strategies to upgrade the managerial and technical dexterities of the small business Indian operators. After thorough revision of relevant literature on small businesses and its management, the researchers used a well structured questionnaire and in-depth personal interviews with 586small business operators selected from manufacturing, trading (retailing and wholesaling), finance, servicing/repair businesses which are located in the coastal districts of Andhra Pradesh in India. The researchers have used convenience sampling and collected data was analyzed with the support of Microsoft Excel and frequency distribution. Noticeably, majority of the small businessmen in India are facing myriad number of challenges both in management and at the time of establishment of their business operations. In particular, 72.47 percent of small businesses operators' have substantiated their strong opinion towards the challenges they are facing particularly finance, marketing and other problems while managing their businesses. The researchers also attempted to get the opinions on problems of the various categories of small businesses while starting their operations. A staggering 68percent of respondents identified the problems related to preparation of business plan, location selection, marketing and other problems like lack of proper credit facilities, skilled manpower, and other infra related problems while setting up of their businesses. On an average, 64.62 and 63.51 percent of small businesses are facing various kinds of problems both at the time of day-to-day management as well as start-up of their businesses respectively. The present research confined with the opinions of only four categories of small business operators particularly from the manufacturing, finance, trading (retailing and wholesaling), and servicing/repair which are continuing their business operations from the nine coastal districts of Andhra Pradesh in India. The present study emphatically provides concrete information required to the business community for identifying an assortment of challenges faced by different small business operators in managing and at the time of their inception. This research paper is first of its kind from this part of the world by offering extensive and credible information required for prospective entrepreneurs in facing the dynamic challenges in managing their business. Furthermore, this research presents invaluable inputs to the stakeholders like all types of governments, policy makers, practitioners, researchers, and educators' about the various impediments faced by the small business community in India.

• 한국정보과학회논문지:데이타베이스
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• 제30권4호
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• pp.372-380
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• 2003

시간에 따라 변화하는 사건들을 저장하는 시간지원 데이타베이스에서 기존의 집계 처리 기법에 시간을 고려하여 처리하도록 확장해야 한다. 기존의 시간지원 집계 처리 기법들은 매번 질의의 대상이 되는 사건들이 다를 때마다 시간 구간을 반복해서 구하고 그 구간마다의 결과를 계산해야 한다는 문제점이 있다. 본 논문에서는 시간지원 데이타베이스에 저장된 사건의 시작 시간과 종료 시간만을 미리 읽어 들여서 구성한 시점 시퀀스를 이용하여 시간지원 집계를 처리하는 방법을 제안하였다. 또한 데이타베이스에서 저장된 사건의 삭제나 새로운 사건의 삽입에 따른 시점 시퀀스 갱신의 용이성에 대해서도 언급하였다. 시점 시퀀스는 시간 구간에 대한 정보를 미리 저장하고 있기 때문에, 질의의 대상이 되는 사건들이 다른 시간지원 집계 질의가 계속해서 들어올 때 기존의 방법에 비해 효율적으로 처리할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권8호
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• pp.2796-2813
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• 2014

This paper presents a new algorithm called the adaptive logarithmic increase and adaptive decrease algorithm (A-LIAD), which mainly addresses the Round-Trip Time (RTT) fairness problem in satellite networks with a very high propagation delay as an alternative to the current TCP congestion control algorithm. We defined a new increasing function in the fashion of a logarithm depending on the increasing factor ${\alpha}$, which is different from the other logarithmic increase algorithm adopting a fixed value of ${\alpha}$ = 2 leading to a binary increase. In A-LIAD, the ${\alpha}$ value is derived in the RTT function through the analysis. With the modification of the increasing function applied for the congestion avoidance phase, a hybrid scheme is also presented for the slow start phase. From this hybrid scheme, we can avoid an overshooting problem during a slow start phase even without a SACK option. To verify the feasibility of the algorithm for deployment in a high-speed and long-distance network, several aspects are evaluated through an NS-2 simulation. We performed simulations for intra- and interfairness as well as utilization in different conditions of varying RTT, bandwidth, and PER. From these simulations, we showed that although A-LIAD is not the best in all aspects, it provides a competitive performance in almost all aspects, especially in the start-up and packet loss impact, and thus can be an alternative TCP congestion control algorithm for high BDP networks including a satellite network.

• 대한기계학회논문집
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• 제17권5호
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• pp.1237-1245
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• 1993

본 연구에서는 그 동안 본 실험실에서 태양열 집열기용으로 개발한 에탄올 열파이프를 집열판에 설치하여 집열기 모델을 설계 제작하였다. 그리고 실제 태양 복사하에서 집열기의 집열과 열이송과정에 대한 특성을 검토함으로써 열파이프의 적 응성을 확인하였다. 특히 열파이프의 시동 및 작동상태, 집열판내의 열유동과정 그리고 집열기의 집열효율에 관하여 고찰하였다.

• 정보처리학회논문지C
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• 제11C권2호
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• pp.229-234
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• 2004

본 논문에서는 RFC 규격을 준수하는 정상적인 TCP와 속도를 제한하는 여러 제약을 무시한 TCP 간의 성능을 비교하였다. 이를 위하여, TCP의 속도에 영향을 미치는 주요 항목들을 결정하였으며, 리눅스 커널의 TCP 소스에서 결정된 항목들을 제거하고 정상적인 TCP와의 성능을 비교하였다. 본 연구 결과를 살펴보면, 목적지가 근거리인 경우 패킷 에러가 발생하지 않는다면 정상적인 TCP와 본 연구에서 수정된 TCP간의 파일 전송 시간의 차이가 그다지 크게 나지 않았다. 하지만, 원거리에 있는 목적지로 웹 페이지와 같은 작은 크기의 파일을 전송할 경우, 혼잡제어 메커니즘 중 저속 출발(slow start)을 적용하지 않았을 때는 전송 시간에서 매우 큰 차이를 나타냈다. 또한, 어느 정도의 패킷 에러가 발생되는 환경에서는 목적지가 근거리이건 원거리이건 혼잡제어를 하지 않도록 수정된 TCP가 RFC 규격을 준수하는 표준 TCP에 비해 빠른 전송 속도를 나타냈다.

• 한국도로학회논문집
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• 제19권4호
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• pp.69-78
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• 2017

PURPOSES : In this study, we analyzed the road crossing behavior of older pedestrians on a mid-block signalized crosswalk, and compared it to that of younger pedestrians. In addition, we analyzed the correlation between accidents involving older pedestrians while crossing roads and their behavioral characteristics. Finally, we confirmed the reasons for an increase in accidents involving older pedestrians. METHODS : First, 30 areas with the highest incidence of accidents involving older pedestrians while crossing roads were selected as target areas for analysis. Next, we measured the start-up delay (the time elapsed from the moment the signal turns green to the moment the pedestrian starts walking) and head movement (the number of head turns during crossing a road) of 900 (450 older and 450 younger) pedestrians. The next step was to conduct a survey and confirm the differences in judgment between older and younger pedestrians about approaching vehicles. Finally, we analyzed the correlation between the survey results and traffic accidents. RESULTS : The average start-up delay and head movement of the older pedestrians was 1.58 seconds and 3.15 times, respectively. A definite correlation was obtained between head movement and the frequency of pedestrian traffic accidents. The results of our survey indicate that 17.3% of the older pedestrians and 7.8% of the younger pedestrians have a high crash risk. CONCLUSIONS : Behavioral characteristics of older pedestrians were closely correlated with accidents involving older pedestrians while crossing roads in mid-block signalized crosswalks. Our study indicates that in order to reduce the number of accidents involving older pedestrians, it is necessary to develop an improvement plan including measures such as installation of safety facilities taking the behavioral characteristics of older pedestrians into consideration and their safety education.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.150-155
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• 2000

Exhaust emissions from vehicles are the main source of air pollution. Many researchers are trying to find the way of reducing vehicle emissions, especially in the cold transient period of the FTP-75 test. In this study, UEGI (Unburned Exhaust Gas Ignition) technology, warming up the close-coupled catalytic converter (CCC) by igniting the unburned exhaust mixture using two glow plugs installed in the upstream of the catalyst, was developed. It was applied to an exhaust system with a hydrocarbon adsorber to ensure an effective reduction of HC emission during the cold start period. Results showed that the CCC reaches the light-off temperature (LOT) in a shorter time compared with the baseline exhaust system, and HC and CO emissions are reduced significantly during the cold start.

• 대한교통학회지
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• 제20권5호
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• pp.23-31
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• 2002

교차로에 진입하는 차량의 차두시간은 포화교통류율과 밀접한 관계가 있으며, 포화차두시간과 출발손실시간을 구하기 위한 기본 파라메터이다. 이러한 차두시간은 운전자의 행태 및 교차로의 특성을 반영하는 것이므로 어느 교차로에서나 일정한 것이 아니라 교차로의 차로수 차로위치, 현시방법, 지역특성 및 시간대 등에 영향을 받는다. 본 논문에서는 각각에 대해 교차로의 특성을 고려하여 적절한 값을 제시하였다. 직진차로수는 1차로, 2차로, 3차로로 분류하고 차로위치는 상위차로, 중간차로, 하위차로로 분류하여 차두시간을 조사한 결과 직진1차로와 직진2차로-상위차로 및 직진3차로-하위차로의 경우 각각 1.73초, 1.71초, 1.93초로 나타났다. 또한 차두시간과 포화교통류율의 관계를 이용하여 주거지역을 1.00로 가정하고 지역특성계수를 산정한 결과 0.96으로 나타났다. 출발손실시간의 경우 방향보호좌회전이 1.41초, 직좌동시신호가 3.27초로 큰 차이가 있었으므로 현시방법에 따라 다른 출발손실시간이 적용되어야 하는 것으로 나타났다.

• 한국운동역학회지
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• 제17권4호
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• pp.149-156
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• 2007

The purpose of this study was to compare the world class women's hurdlers with kinematic variables Lee Yeon-Kyoung's in the 100m hurdle. Among korea elite female hurdler, Lee Yeon-Kyoung was participated as a subject. Eight JVC video cameras(GR-HD1KR) were used to film the performance of Lee Yeon-Kyoung at a frame rate of 60fields/s. The real-life three-dimensional coordinate data of digitized body landmarks were smoothed using a fourth order Butterworth low pass recursive digital filter with an estimated optimum cutoff frequency of 7.4Hz. After analyzing and comparing Lee Yeon Kyung's kinematic variables with the world top class hurdlers in the woman's 100m hurdle run, the following conclusions were obtained. 1. Lee should be able to increase the speed with over 5.4m/s from start to first hurdle and then maintain the speed range from 8.33m/s to 8.67m/s until 10th hurdle. Lee should have to maintain the speed with 8.51m/s from 10th hurdle to finish line. 2. Lee has to reach her maximum running speed at 5th hurdle and then has to shorten running time with 0.5sec between hurdles. 3. Lee should be able to run around 2.5sec from start to frist hurdle and then maintain under 1.00sec following phases. Lee should be able to maintain under 1.10sec from 10th hurdle to finish line. 4. Lee needs to control a consistent takeoff and landing distance pattern, Lee needs to lower the height of the center of gravity of the body with 0.33m when she clears the hurdles.

• 한국수소및신에너지학회논문집
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• 제32권5호
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• pp.315-323
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• 2021

The air-cooled proton exchange membrane fuel cells (PEMFC) stacks, which is widely used in small-sized PEMFC, have a problem in that durability is weaker than that of the water-cooled type. Because the cathode is open to the atmosphere and the structural problem of the air-cooled stack, which is difficult to maintain airtightness, is highly likely to form a hydrogen/air boundary during start-up/shut-down (SU/SD). Through the accelerated durability evaluation of the 20 W air-cooled PEMFC stack, the purpose of this study was to find out the cause of the degradation of the stack and to contribute to the improvement of the durability of the air-cooled PEMFC stack. In this study, it was possible to evaluate durability in a relatively short time by reducing 20-30% of initial performance by repeating SU/SD 1,000 to 1,200 times on an air-cooled PEMFC stack. After disassembling the stack, each cell was divided into two and the performance analysis showed that the electrode degradation was more severe in the anode outlet membrane electrode assembly (MEA), which facilitates air inflow as a whole, than in the inlet MEA. It was shown that the cathode Pt was dissolved/precipitated to deteriorate the polymer ionomer inside the membrane.