• 한국CDE학회논문집
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• 제2권3호
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• pp.195-210
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• 1997

In Rapid Prototyping process, the time required to build multiple prototype parts can be reduced by packing several parts optimally in a work volume. Interactive arrangement of the multiple parts is a tedious process and does not guarantee the optimal placement of all the parts. In this case, packing is a kind of 3-D nesting problem because parts are represented by STL files with 3-D information. 3-D nesting is well known to be a problem requiring an intense computation and an efficient algorithm to solve the problem is still under investigation. This paper proposes that packing 3-D parts can be simplified into a 2-D irregular polygon nesting problem by using the characteristic of rapid prototyping process that the process uses 2-dimensional slicing data of the parts and that slice of the STL parts are composed of polygons. Our algorithm uses no-fit-polygon (NFP) to place each slice without overlapping other slices in the same z-level. The allowable position of one part at a fixed orientation for given parts already packed can be determined by obtaining the union of all NFP's that are obtained from each slice of the part. Genetic algorithm is used to determine the order of parts to be placed and orientations of each part for the optimal packing. Optimal orientation of a part is determined while rotating it about the axis normal to the slice by finite angles and flipping upside down. This algorithm can be applied to any rapid prototyping process that does not need support structures.

• Journal of Rhinology
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• 제25권2호
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• pp.86-90
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• 2018

Background and Objectives: Although polyvinyl acetate ($Merocel^{(R)}$) has been widely used as a packing material after septoplasty, removable nasal packing can increase patient discomfort, local pain, and pressure. Furthermore, the removal of nasal packing has been described as the most uncomfortable and distressing feature associated with septoplasty. The purpose of this study was to investigate the efficacy of polyvinyl acetate with carboxymethyl cellulose sheet ($Rhinocel^{(R)}$) nasal packing on patient subjective symptoms, degree of bleeding, hemostasis, and wound healing following septoplasty. Subjects and Method: Forty patients with nasal septum deviation requiring septoplasty were included. Following surgery, one nasal cavity was packed with $Rhinocel^{(R)}$ and the other one with $Merocel^{(R)}$. Patient subjective symptoms while the packing was in situ, hemostatic properties, pain on removal, degree of bleeding on removal, duration of hemostasis after removal, postoperative wound healing, and the cost of the pack were evaluated. Results: Although the two types of packing materials were equally effective in controlling postoperative bleeding after septoplasty, $Rhinocel^{(R)}$ was significantly more comfortable while in situ and less painful on removal than $Merocel^{(R)}$, which was associated with significantly more bleeding on removal and so more time was needed to control hemorrhage. There was no significant difference in postoperative wound healing or pack cost. Conclusion: The use of $Rhinocel^{(R)}$ after septoplasty has less discomfort, greater patient satisfaction, and less bleeding on removal with no adverse reactions compared to $Merocel^{(R)}$ packing. Therefore, $Rhinocel^{(R)}$ may be a useful packing material after septoplasty.

• 농업과학연구
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• 제40권2호
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• pp.93-99
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• 2013

The disease and insect were surveyed locally in greenhouse, fruit packing house and store house of 51 farms in 13 towns having purpose of paprika exportation. By analysis, various disease and insect were not only founded locally but more ones detected in farms having old facilities and no natural enemy. We found 15 pathogens such as Fusarium spp., Alternaria solani, Leveilluila taurica, PepMV (Pepino mosaic virus) and TMV (Tobacco mosaic virus) in greenhouse, Fusarium spp. in fruit packing house and Penicillium spp. in store house. We found 15 insects in greenhouse such as Bemisia tabaci, rialeurodes vaporariorum and Myzus persicae in greenhouse, Hylobitelus haroldi in fruit packing house. However, the problem quarantine disease and insect for importation and exportation were not detected in inspection time.

• 한국통신학회논문지
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• 제37권4B호
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• pp.278-287
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• 2012

본 논문에서는 NCW 환경에서 Link-16 전술데이터링크를 통해 이미지 정보를 신속 정확하게 전송하여 작전효율을 증대시키기 위한 메시지 패킹 기법을 제안한다. 제안하는 메시지 패킹구조는 기존의 Link-16 메시지와 호환성을 유지하면서 하나의 타임슬롯 내에서 데이터 전송율을 증가시킬 수 있도록 COC(Cyclic shifted Orthogonal Complementary) 웨이브폼의 가변 코드율을 적용하여 주파수 사용 효율을 향상시키고, 특히 동적 TDMA 환경에서 타임슬롯을 연속으로 전송 할 때, 시간 자원 이용률이 높은 패킹구조를 함께 사용하게 되면 동일한 타임슬롯내에 더 많은 데이터를 전송할 수 있도록 하였다. 모의실험을 통해 제안한 방식의 성능 및 우수성을 비교하고 제안 방식의 타당성을 보인다.

• 한국재난정보학회 논문집
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• 제7권1호
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• pp.12-20
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• 2011

본 연구는 군중집회 및 군중눌림 현상의 문헌조사 및 분석에 근거하여 군중집회 및 군중집회에서의 인명피해의 특성을 알아보고자 수행되었다. 대규모 군중집회 시 인명 피해의 특성은 참가자 수와 군중 밀도가 군중집회 종류와 특성에 따라 다른 영향을 미치고 있었다. 군중 집회에 영향을 주는 변수와 그 원인들은 상황에 따라 다양한 정 혹은 부의 영향을 미치고 있었으며 그 변수들은 날씨, 참가자 수, 행사 기간, 실외와 실내, 착석과 이동, 행사 유형, 군중 감정상태, 술 혹은 약물, 군중 밀도, 관련 시설, 참가자 연령 등이었다. 이 중 군중 눌림현상은 실험적으로도 연구가 가능하였고, 사고가 유발되는 물리적 기전으로 보아 군중 압력과 군중 밀도 및 압력의 지속 시간에 영향을 받았으나 사망에 이르는 구체적인 압력 수치를 도출하려면 인간 신체와 관련된 여러 외부적 영향으로 인하여 추가적 연구가 더 필요하다.

• 한국기계가공학회지
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• 제18권3호
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• pp.59-65
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• 2019

In many industries, particle packing is adopted quite frequently. In the particle packing process, the Discrete Element Method (DEM) can analyze the multi-collision of particles efficiently. Two types of contact models are frequently used for the DEM. One is the linear spring model, which has the fastest calculation time, and the other is the Hertz-Mindlin model, which is the most frequently used contact model employing the DEM. Meanwhile, very tiny particles in the micrometer order are used in modern industries. In the micro length order, surface force is important to decreased particle size. To consider the effect of surface force in this study, we performed a simulation with the Hertz-Mindlin model and added the Johnson-Kendall-Roberts (JKR) theory depicting surface force with surface energy. In addition, three contact models were compared with several parameters. As a result, it was found that the JKR model has larger residual stress than the general contact models because of the pull-off force. We also validated that surface force can influence particle behavior if the particles are small.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.443-450
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• 2016

This paper deals with a kind of packing problem of which the goal is to compose one or more templates which will be used to produce the items of different types. Each template consists of a fixed number of slots which are assigned to the different types of items and the production of the items is accomplished by printing the template repeatedly. The objective is to minimize the total number of produced items. This problem is known to be NP-hard. We present a polynomial time approximation algorithm which has a constant approximation ratio. The proposed algorithm is based on the well-known first-fit strategy.

• KSBB Journal
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• 제16권3호
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• pp.314-319
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• 2001

A nitrifier consortium immobilized in polyvinyl alcohol was used to remove ammonia nitrogen from synthetic wastewater in an airlift bioreactor. The minimum aeration rates were 0.4, 0.6, 0.8 and 1.0 vvm for 5, 10, 15 and 20% immobilized bead packing volume fraction, respectively. The efficient packing fraction and the aeration rate for ammonia nitrogen removal were 15% and 2.4 vvm, respectively. With a hydraulic retention time of 0.5hr, the removal rate and the efficiency of ammonia nitrogen removal were 1685 g/㎥$.$day and 48% at an influent ammonia nitrogen concentration of 75 g/㎥.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.311-314
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• 2004

The 2 DBPP(Two-Dimensional Bin Packing Problem) is a problem of packing each item into a bin so that no two items overlap and the number of required bins is minimized under the set of rectangular items which may not be rotated and an unlimited number of identical rectangular bins. The 2 DBPP is strongly NP-hard and finds many practical applications in industry. In this paper we discuss a tabu search approach which includes tabu list, intensifying and diversification strategies. The HNFDH(Hybrid Next Fit Decreasing Height) algorithm is used as an internal algorithm. We find that use of the proper parameter and function such as maximum number of tabu list and space utilization function yields a good solution in a reduced time. We present a tabu search algorithm and its performance through extensive computational experiments.

• ETRI Journal
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• 제28권4호
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• pp.475-485
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• 2006

Network-on-chip (NoC) is an emerging design paradigm intended to cope with future systems-on-chips (SoCs) containing numerous built-in cores. Since NoCs have some outstanding features regarding design complexity, timing, scalability, power dissipation and so on, widespread interest in this novel paradigm is likely to grow. The test strategy is a significant factor in the practicality and feasibility of NoC-based SoCs. Among the existing test issues for NoC-based SoCs, test access mechanism architecture and test scheduling particularly dominate the overall test performance. In this paper, we propose an efficient NoC-based SoC test scheduling algorithm based on a rectangle packing approach used for current SoC tests. In order to adopt the rectangle packing solution, we designed specific methods and configurations for testing NoC-based SoCs, such as test packet routing, test pattern generation, and absorption. Furthermore, we extended and improved the proposed algorithm using multiple test clocks. Experimental results using some ITC'02 benchmark circuits show that the proposed algorithm can reduce the overall test time by up to 55%, and 20% on average compared with previous works. In addition, the computation time of the algorithm is less than one second in most cases. Consequently, we expect the proposed scheduling algorithm to be a promising and competitive method for testing NoC-based SoCs.