• International conference on construction engineering and project management
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• 2022.06a
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• pp.484-491
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• 2022

A paradigm shift in teaching modular construction in higher education and K-12 is proposed as a means to increase the future adoption of the modular construction technique. To this effect, a new education module is presented to STEM educators. This education module is based on LEGOs and directed towards educators in the architecture, engineering, and construction (AEC) industry. The main objectives of the education module are to increase interest and knowledge of modular construction, acknowledge the benefits of using 3D design with 4D scheduling, and create a simulating hands-on educational opportunity. The education module is designed to allow participants to experience a hands-on simulation of modular construction and stick-built construction through building a LEGO project. Participants are challenged to find the advantages and disadvantages in both construction systems first-hand and record their findings. Results are presented from the preliminary testing of this education model on a group of construction management students at the University of Nevada, Las Vegas. Overall, the survey results showed that the LEGO education module was successful at achieving the project's three main objectives: 1) increasing the participants' interest and knowledge of modular construction through an interactive project; 2) increasing the participants' understanding of the benefits of 3D design with 4D scheduling over the use of 2D drawings; and 3) creating a simulating hands-on educational opportunity to help participants compare modular construction to stick-built construction. In the end, this proposed a new LEGO education module addressing the problems identified from this study with more participants.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.391-393
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• 2005

IEEE 802.16은 BWA (Broadband Wireless Access) 시스템의 표준으로 현재 많은 연구와 함께 상용 제품에 대한 연구가 진행중인 분야이다. IEEE 802.16에서는 QoS를 제공하기 위하여 BS (Base Station)와 SS(Subscriber Station)간의 QoS 협상 과정을 정의하고 있으며, BS 및 SS에서의 효율적인 QoS 보장을 위해 4가지의 서비스 클래스를 정의하고 있다. 이러한 서비스 클래스는 UGS, rtPS, nrtPS, 그리고 BE 이다. 하지만 표준에서는 이러한 서비스 클래스를 어떻게 이용할 것인지에 대한 언급이 없으며, 이에 따라 효율적인 packet scheduling에 관한 많은 연구가 진행되어 왔다. 기존의 연구에서는 주로 BS에서의 효율적인 Scheduling에 초점을 맞추어 연구가 진행되었으며, SS에서의 Scheduling에 대한 연구는 거의 되어 있지 않다. 하지만 BS에서 SS에게 대역폭을 할당할 때 GPSS (Grants per subscriber station) mode로 대역폭을 할당한다면 SS에서는 할당 받은 대역폭을 효율적으로 사용하기 위하여 scheduling이 필요하다. 본 논문에서는 SS에서의 scheduling architecture를 제안하고자 한다. 제안하는 scheduling architecture는 기존의 scheduling algorithm과는 달리 각 서비스 클래스에 대해서 효과적인 scheduling이 가능하도록 함으로써 시스템의 성능을 높이는데 기여할 것이다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.388-390
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• 2005

IEEE 802.16은 BWA (Broadband Wireless Access) 시스템의 표준으로 현재 많은 연구와 함께 상용 제품에 대한 연구가 진행중인 분야이다. IEEE 802.16에서는 QoS를 제공하기 위하여 BS (Base Station)와 SS(Subscriber Station)간의 QoS 협상 과정을 정의하고 있으며, BS 및 SS에서의 효율적인 QoS 보장을 위해 4가지의 서비스 클래스를 정의하고 있다. 이러한 서비스 클래스는 UGS, rtPS, nrtPS, 그리고 BE 이다. 하지만 표준에서는 이러한 서비스 클래스를 어떻게 이용할 것인지에 태한 언급이 없으며, 이에 따라 효율적인 packet scheduling에 관한 않은 연구가 진행되어 왔다. 기존 연구에서는 주로 BS에서의 효율적인 scheduling에 초점을 맞추어 연구가 진행되었으며, SS에서의 scheduling에 대한 연구는 거의 되어 있지 않다. 하지만 BS에서 SS에게 대역폭을 할당할 때 GPSS (Grants per subscriber station) mode로 대역폭을 할당한다면 SS에서는 할당 받은 대역폭을 효율적으로 사용하기 위하여 scheduling이 필요하다. 본 논문에서는 SS에서 효율적인 대역폭 사용을 가능하도록 하기 위한 scheduling 알고리즘을 제안하고자 한다. 제안하는 알고리즘은 SS의 상황에 맞추어서 주어진 대역폭을 보다 더 효과적으로 이용하는데 초점을 맞추고 있다. 성능 명가를 통하여 제안하는 알고리즘이 기존 알고리즘에 비해서 보다 더 효율적으로 대역폭을 사용함을 알 수 있다.

• The KIPS Transactions:PartC
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• v.18C no.6
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• pp.433-440
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• 2011

In this paper, we propose a new scheduling method that can guarantee reliable jitter by minimizing the queue length variation in the streaming service provisioning such as IPTV and VoD. The amount of traffic to be delivered within a certain time is very fluid because MPEG-4 and H.264 encoders use VBR(Variable Bit Rate) for delivering video streaming traffic. This VBR characteristic increases the end-to-end propagation delay variation when existing scheduling methods are used for delivering video frames. Therefore, we propose the new scheduling method that can minimize change rate of queue length by adaptively controling service rate taking into account the size of bulk incoming packets and arrival rate for bulk streaming traffic. Video frames can be more reliably transmitted through the minimization of the queue length variation using the proposed method. We use the queueing model and also carry out OPNET simulation to validate the proposed method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.12
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• pp.61-68
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• 2010

In this paper, we investigate the performance of ARQ-aided Time Switched Transmit Diversity (ARQ-TSTD) applying the multi-level control signaling in the WCDMA LCR-TDD system. Proposed ARQ-TSTD system applies the multi-level control signaling scheme in which the receiver sends the response signal (ACK or NACK signal) to the transmitter and defines NACK2 signal for multi-level control. Transmitter utilize the NACK2 control signal to the postponement of transmission and multi-user scheduling scheme proposed by this paper. Simulation results demonstrate that the proposed postponement of transmission and multi-user scheduling scheme yield about 1.3dB, 1.4dB performance gain respectively, compared with the conventional ARQ-TSTD with antenna switching scheme in tenn of the frame error rate (FER) for mobile speed of 3km/h and FER value of 10%. In addition, 14% and 11.5% of throughput gain respectively is shown when Eb/N0=-3dB.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.61-68
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• 2007

There has been a lot of research on and release of commercial systems that enable evaluation and visualization of construction methods. These have enabled the selection of good construction plans. However, the process in which engineers build 3D geometry, formulate a schedule and eventually synchronize them is still a time-consuming process. Changing any aspect of the geometry or the schedule and re-linking them is also time-consuming. Therefore, the engineers may compromise on getting the best solution. This paper describes a technique to automate the generation of multiple sets of schedules, quantity takeoffs and 4D visualization from a single 3D model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.12 no.19
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• pp.39-47
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• 1989

This paper considers a multi-stage flowshop scheduling Problem where the setup times of jots depend on immediately preceding jobs. Three heuristics algorithms, CAMPBELL, PEIDAN and CAMRING are proposed. The performance measure is a minimization of makespan. The parameters of simulation model are PS(ratio of the processing times to setup times), M(number of machines), and N(number of job). This simulation model for each algorithm is a 4$\times$3$\times$3 factorial design with 360 observations. The makespan of the proposed heuristic algorithms is compared with the optimal makespan obtained by the complete enumeration of schedules. This yardstick of comparison is defined as a relative error. The mean relative error of CAMPBELL, PEIDAN, and CAMRING algorithms are 4.353%, 7.908%, and 8.578% respectively. The SPSS, is used to analyse emphirical results. The experimental results show that the three factors are statistically significant at 5% level.

• IE interfaces
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• v.25 no.2
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• pp.216-228
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• 2012

BIM-based 4D simulation makes people easily understand complex construction process using 3D graphics model and helps them review and identify the construction schedule in each phase of the construction process. Moreover, 4D simulation can be used as reference data to determine the validity of the process in the design phase and will be utilized as a measure for checking the construction process. Therefore 4D simulation of construction improves efficiency of project management. However, current commercial applications available for 4D simulation do not provide sufficient functions for connection of 3D models and process information. In this paper, we propose an automated generation method through the definition of the process based on a work method template and developed the template based schedule generation system (TSGS).

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.21
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• pp.91-100
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• 1990

This paper is concerned with the development of optimal algorithms for multi-stage flowshop scheduling problems with sequence dependent setup times. In the previous researches the setup time of a job is considered to be able to begin at the earliest opportunity given a particular sequence at the start of operations. In this paper the setup time of a job is considered to be able to begin only at the completion of that job on the previous machine to reflect the effects of the setup time to the performance measure of sequence dependent setup time flowshop scheduling. The results of the study consist of two areas; first, a general integer programming(IP) model is formulated and a nixed integer linear programming(MILP) model is also formulated by introducing a new binary variable. Second a depth-first branch and bound algorithm is developed. To reduce the computational burdens we use the best heuristic schedule developed by Choi(1989) as the first trial. The experiments for developed algorithm are designed for a 4$\times$3$\times$3 factorial design with 360 observations. The experimental factors are PS(ratio of processing time to setup time), M(number of machines), N(number of jobs).

• ETRI Journal
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• v.31 no.4
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• pp.469-471
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• 2009

This letter proposes a weighted scheduling mechanism for Internet protocol television (IPTV) to improve the loss performance of multicast transmission over an Ethernet passive optical network (EPON). We propose a new weight policy from the number of multicast receivers to proportionally allocate the downstream bandwidth of IPTV traffic. The proposed mechanism is used in an optical line terminal to decrease lost packets of favorite IPTV services because the lost multicast packets are proportional to the number of receivers. The total proportion of lost multicast packets is reduced by up to 73% in an EPON.