• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.570-571
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• 2017

The manufacturing industry is evolving from the automation process to the intelligent process through ICT convergence As the spread of 3D printers, 3D printing technology is becoming a technology that leads the Industry4.0. In this paper, we propose and implement a multi-3D printer management structure and control method based on IoT optimized for personalized manufacturing services.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.995-1002
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• 2018

A Contention Access Period(: CAP) with high contention in priority-based MAC protocols can result in higher number of collisions and retransmissions. High-Priority traffic dominates low-priority traffic during CAP depleting low-priority traffic, adversely affecting WBAN throughput, delay, and energy consumption. This paper proposes a Emergency data-First-Priority MAC(: EFP-MAC) superframe structure that is able to reduce contention in the CAP period, and provides a fair chance for low-priority traffic. As a result, the proposed Emergency data-First Priority MAC(; EFP-MAC) The Simulation results show that the proposed MAC achieves lower energy consumption, higher throughput and low latency than the IEEE 802.15.4 standard.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.578-580
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• 2017

IoT technology poses a lot of security threats. Various algorithms are thus employed in ensuring security of transactions between IoT devices. Advanced Encryption Standard (AES) has gained huge popularity among many other symmetric key algorithms due to its robustness till date. This paper presents a hardware based implementation of the AES algorithm. We present a four-stage pipelined architecture of the encryption and key generation. This method allowed a total plain text size of 512 bits to be encrypted in 46 cycles. The proposed hardware design achieved a maximum frequency of 1.18GHz yielding a throughput of 13Gbps and 800MHz yielding a throughput of 8.9Gbps on the 65nm and 180nm processes respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1702-1710
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• 2009

In this paper, we propose a problem space based search(PSBS) algorithm to solve parallel machine scheduling problem considering rework probabilities. For each pair of a machine and a job type, rework probability of each job on a machine can be known through historical data acquisition. Neighborhoods are generated by perturbing four problem data vectors (processing times, due dates, setup times, and rework probabilities) and evaluated through the efficient dispatching heuristic (EDDR). The proposed algorithm is measured by maximum lateness and the number of reworked jobs. We show that the PSBS algorithm is considerably improved from the result obtained by EDDR.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.1
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• pp.58-67
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• 2021

This paper describes the development for the dual thrust rocket motor with two types of propellants with different combustion characteristics. We developed the composition of two kinds of propellant to be applied to a rocket motor, and improved a propellant charging process in a free grain type to improve the adhesion method and the problems of adhesion between different propellants. In addition, to meet the ignition phenomenon as a small rocket motor, the ignition delay was improved by applying a nozzle plug developed in a high density foam. The propulsion rocket motor reflecting this design and the improved manufacturing process was evaluated through a ground performance test.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.15-17
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• 2022

In order to minimize surplus parts in ball bearing selective assembly systems, it is necessary to optimize the selection probability by grasping the dimensional distribution of each part. But the use of a complex system causes delays in the production process. In this paper, we propose cluster priority selection algorithm that can quickly and simply determine the selection priority in ball bearing selective assembly system. In addition, we assume the simulated situation with the data collected in the actual ball bearing selective assembly process, and evaluate the incidence of surplus part and runtime by simulating the cluster priority selection algorithm and the exiting algorithm. As a result of the simulation, the cluster priority selection algorithm generated 83.8% less surplus parts, and 39.7% less runtime than the existing algorithm.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.11a
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• pp.106-109
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• 2005

확산형 시료 채취기와 직독식 기기(공정시험법, Nitrogen Oxides Analyzer Model; EC 9841, Ecotech, Australia)에 의한 $NO_2$, 농도를 비교하고, 능동시료채취기(공정시험법)와 확산형포집기에 의한 HCHO(포름알데히드) 농도를 비교하기 위해 서울 ${\cdot}$ 경기 또는 대전, 충남 ${\cdot}$ 북지역에 소재한 11개 시설(종합병원 4곳, 노인 병원 1곳, 보건소 1곳, 복지관 3곳, 보육시설 2곳)을 대상으로 수행하였다. 1. 포름알데히드의능동 포집법(공정시험법)에 의한 시료(n=87)의 평균농도는 $11.44{\pm}11.07ppb$이고, 확산형 시료 채취기 의한 시료(n=40)의 평균농도는 $11.91{\pm}7.37ppb$으로 비슷한 값이 나왔고, 통계적으로 유의하지 않았다(p=0.806). 2. 포름알데히드 능동 포집법에 의한 농도와 확산형 시료 채취기에 의한 농도와의 상관계수 r=0.404(p=0.037)로 나타나 이 두 가지의 방법은 특정시간 포름알데히드 측정에 사용하여도 어느 정도 비교하기에는 적합할 것으로 생각된다. 3. 이산화질소의 노출정도는 직독식 기기(공정시험방법)와 확산형 시료 채취기로 각각 1시간 (오전, 오후 각각 2회), 8시간 측정하였다. 공정시험방법(n=61)에 의한 1시간-시료 평균농도는$44.48{\pm}37.96ppb$이고, 확산형 시료 채취기(n=61)에 의한 1시간-시료 평균농도는 $3.58{\pm}2.07ppb$으로 통계적으로 유의하였다(p=0.000). 직독식 기기(n=61)에 의한 8시간-시료 평균농도는 $34.85{\pm}22.83ppb$이고, 확산형 시료 채취기(n=61)에 의한 8시간-시료 평균농도 $8.32{\pm}4.44ppb$으로 통계적으로도 유의하였다(p=0.000). 4. 이산화질소를 직독식 기기(공정시험방법)와 확산형 시료 채취기로 측정한 1시간-시료 농도의 상관계수 r=0.253(p=0.268)이고 8시간-시료 일 때 상관계수 r=0.367(p=0.102)로 나타나 확산형 시료 채취기를 직독식 기기(공정시험방법) 대체 사용방법으로 이용하기에는 적합하지 않다고 생각된다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.80-89
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• 2006

The rapid development of process technology and the introduction of new materials not only make it difficult for process control but also as a result increase process variations. These process variations are barriers to successful implementation of design circuits because there are disparities between data on layout and that on wafer. This paper proposes a new design environment to determine the interconnect worstcase with accuracy and speed so that the interconnect effects due to process-induced variations can be applied to designs of $0.13{\mu}m$ and below. Common Geometry and Maximum Probability methods have been developed and integrated into the new worstcase optimization algorithm. The delay time of the 31-stage Ring Oscillator, manufactured in UMC $0.13{\mu}m$ Logic, was measured, and the results proved the accuracy of the algorithm. When the algorithm was used to optimize worstcase determination, the relative error was less than 1.00%, two times more accurate than the conventional methods. Furthermore, the new worstcase design environment improved optimization speed by 32.01% compared to that of conventional worstcase optimizers. Moreover, the new worstcitse design environment accurately predicted the worstcase of non-normal distribution which conventional methods cannot do well.

• The Korean Journal of Petroleum Geology
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• v.14 no.1
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• pp.45-52
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• 2008

The GTL(Gas to Liquids) technology, manufacturing synthesized oil from natural gas, had been developed about 1920 for the military purpose by Fischer and Tropsch, German scientists. And 1960, Sasol company had started commercializing the FT(Fischer-Tropsch) synthesis technology, for the transport fuel in South Africa. Until a recent date, the commercialization of GTL technology had been delayed by low oil price. But concern about depletion of petroleum resources, and development in synthesizing technology lead to spotlight on the GTL businesses. Especially, Qatar, which has rich natural gas fields, aims at utilizing natural gas like conventional oil resources. Therefore, around this nation, GTL plants construction has been promoted. There are mainly 3 processes to make GTL products(Diesel, Naphtha, lube oil, etc) from natural gas. The first is synthesis gas generation unit reforming hydrogen and carbomonoxide from natural gas. The second is FT synthesis unit converting synthesized gas to polymeric chain-hydrocarbon. The third is product upgrading unit making oil products from the FT synthesized oil. There are quite a little sulfur, nitrogen, and aromatic compounds in GTL products. GTL product has environmental premium in discharging less harmful particles than refinery oil products from crude to the human body. In short, the GTL is a clean technology, easier transportation mean, and has higher stability comparing to LNG works.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.669-676
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• 2018

Schedule management in construction work is an important step for determining the construction period. On the other hand, there is a difference between the planned schedule and execution schedule because the estimation and calculation of Non-Working days, in which possible at the design stage is not performed properly. This paper proposes a method for estimating the working days by analyzing characteristics of the major work type and estimating the Non-Working days reflecting the Chuseok and New Year Holidays, which is the closest method to the actual work in the schedule planning. By applying the correction factor of the existing method and the improved method for the same construction in the same site, improved method was reduced by 22 days (9.1%) based on the actual working days. The importance of schedule management was confirmed as an example by comparing the data before and after the application of the standard (plan). These results show that the schedule delays, which are caused by the inconsistency between actual working days calculation that had been practiced conventionally and the working days on the schedule table, can be prevented. In addition, it will help to establish a schedule plan that is closer to reality.