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다품종 소량 판매 환경의 수요 예측을 위한 빅데이터 분석-전자부품 판매 사례를 중심으로
차현철 한국멀티미디어학회 2022 멀티미디어학회논문지 Vol.25 No.12
It is very important for companies to find insights that can be used in making strategic decisions through big data analysis. In this paper, we perform an analysis for demand forecasting focusing on the retail industry that handles multi-variety small-volume in an online environment, especially the sales of electronic parts. Through this, we seek the ways to maintain adequate inventory. We propose the introduction of the concept of risk value and risk index to evaluate the impact of each item according to the prediction error. The risk index proposed in this paper is an easy way to evaluate the degree of risk of error and to accurately select items with a high risk index. In addition, we develop a risk index that can be used in the pre-processing. If the risk index is used, a significant improvement in the average error amount can be expected. Our method is expected to be applicable to other multi-variety small-volume environments as well.
센서 네트워크를 위한 가변 간격 센싱 기능을 가진 안전존 관리 알고리즘의 설계
차현철(Hyun-Chul Cha) 한국컴퓨터정보학회 2016 韓國컴퓨터情報學會論文誌 Vol.21 No.10
In this paper, we propose a scheme to prolong the lifetime of the sensor network by reducing the power consumption of the sensor node. The proposed algorithm reduces the number of transmissions and sensing at the application layer. We combine the VIS scheme with the MSZ algorithm and call it as the SZM/VIS algorithm. The actual temperature data was collected using the sensor nodes to assess the performance of the proposed algorithm. The proposed algorithm was implemented through the programming and was evaluated under various setting values. Experimental results show that the SZM/VIS has a slightly improved transmission ratio than that of the MSZ while has the periodic transmission capability like as the MSZ. Also the SZM/VIS can significantly reduces the sensing ratio like that of the VIS. Our algorithm has the advantages of instantaneous, simplicity, small overhead and robustness. Our algorithm has just negligible side effects by controlling the parameter properly depending on the application types. The SZM/VIS algorithm will be able to be used effectively for the applications that need to be managed within a certain range of specific properties, such like crop management.
센서 네트워크에서 에너지 효율적인 응용 프로토콜의 설계
차현철(Hyun-Chul Cha) 한국산업정보학회 2014 한국산업정보학회논문지 Vol.19 No.2
센서 네트워크의 활용 중 농작물 관리 등의 응용에서는 온도 등의 속성이 적정한 범위 내에서 관리되어야 하며 이를 위한 에너지 효율적인 응용 프로토콜이 반드시 필요하다 하겠다. 본 논문에서는 이런 요구를 충족시킬 수 있는 에너지 효율적인 응용 프로토콜을 제안하였다. 속성을 적정 범위 내에서 관리하기 위해 존 이라는 개념을 사용하는 MSZ 알고리즘을 제안하였다. 또 제안된 알고리즘의 성능을 평가하기 위해 실제 센서노드를 사용하여 온도 자료를 수집한 후 프로그래밍을 통해 알고리즘들을 구현하여 비교하였다. 실험결과 제안한 MSZ 알고리즘은 주기적 전송을 사용하여 센서노드의 상황을 주기적으로 파악할 수 있는 능력을 가지면서도 에너지 효율측면에서 APTEEN 보다 더 좋은 성능을 보여주었다. 본 논문에서 제안한 MSZ 알고리즘은 농작물이나 발효식품 관리처럼 특정 속성을 일정한 범위 내에서 관리하여야 하는 응용에 유용하게 사용될 수 있을 것이다. Some application of the sensor networks such as crop management must control the temperature within a proper range. The energy-efficient applications and protocols for them are needed. In this paper, we propose an energy efficient application protocol which can meet these needs. We use the concept of safety zone to manage the appropriate range of properties within our algorithm. We name our proposed algorithm "MSZ". To assess the performance of the proposed algorithm the actual temperature data was collected using the sensor node. The algorithm was implemented through programming and compared with the other algorithms. Experimental results show that the MSZ algorithm has a much better performance than that of APTEEN in terms of energy efficiency as well as has the ability of determining the status of sensor nodes with the periodical transmitting. Our MSZ algorithm can be useful in applications developments for the management of crops, fermented food and etc.
담배잎의 기내 배양에서 유기된 부정근 분열조직 및 캘러스 세포의 미세구조
차현철,박호일 한국연초학회 1995 한국연초학회지 Vol.17 No.1
Structures of the adventitious root meristem induced from callus culture of tobaco (Nicotiana tabacum cv. NC 82) leaves were investigated by light and transmission electron microscopy. Structural differences between in vitro root and callus cells were also examined by the microscopy. The submicroscopic features of the in vitro root cells were as follows. Intercellular spaces were not developed and nuclei with two nucleoli were observed occasionally. Plasmodesmate were found in groups or sing1y on transverse and longitudinal walls. Amyloplast solely filled with starch grains, with one to five electron - dense bands, was surrounded by single membrane. in the callus cells, vacuolization of central part in the cytoplasm having mitochondria with swollen cristae and starch grains like those of in vitro root cells was a distinct feature. Vesicles which were found between cell wall and plasma membrane may be arisen by a process of protoplasmic invagination. By comparing of ultrastructures between the cells of callus and in vitro roots we found that the distinct differences lied on thickened cell walls and hypertrophed vacuoles in the former, and less thickened cell walls and several small vacuoles in the later.