• Journal of Digital Convergence
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• v.19 no.11
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• pp.351-357
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• 2021

IoT devices, which are used in various ways in distributed environments, are becoming more important in data transmitted and received from IoT devices as fields of use such as medical, environment, transportation, bio, and public places are diversified. In this paper, as a method to ensure the reliability of IoT data, an autoencoder-based IoT-linked processing technique is proposed to classify and process numerous data by various important attributes. The proposed technique uses correlation indices for each IoT data so that IoT data is grouped and processed by blockchain by characteristics for IoT linkage processing based on autoencoder. The proposed technique expands and operates into a blockchain-based n-layer structure applied to the correlation index to ensure the reliability of IoT data. In addition, the proposed technique can not only select IoT data by applying weights to IoT collection data according to the correlation index of IoT data, but also reduce the cost of verifying the integrity of IoT data in real time. The proposed technique maintains the processing cost of IoT data so that IoT data can be expanded to an n-layer structure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.663-668
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• 2010

In driving a car, turns such as left turns, right turns, or u-turns, make the speed of the car decrease considerably. A more straight path, therefore, is probably faster to arrive at the destination than zig-zag path with same distance. In this paper, we have newly proposed the turn heuristic to make more straight path. The path navigation algorithm with turn heuristic(called as TA* algorithm) could enhance the straightness of a path by putting the turned-edges to the turn cost. It requires higher cost to use TA* algorithm than traditional A* algorithm because the straight-edge first searching have increased the search space. We have improved the TA* algorithm into the variable TA* algorithm(called as VTA* algorithm) which adopt the turn-heuristic during the a portion of the whole path.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.11
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• pp.47-55
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• 2004

In this paper, an enhanced time-based registration method is proposed. The method reduces the registration cost when a mobile terminal stays in a cell for a long time. We also analyze the performance of the proposed method numerically. In the analysis, we assume Poisson call arrival distribution and exponential cell resident time. From the analysis we calculate the optimal time-interval. Additionally, limit cost analysis is made to investigate the behaviors in the limit conditions. To compare the performance of the proposed method with the original time-based registration method, we analyze the performance of the original time-based registration method. In the comparisons, we see that the proposed enhanced time-based registration method has better performance and is applicable to the PCS systems.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.1
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• pp.41-50
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• 2010

본 논문에서는 수명이 다한 제품이나 소비자가 더 이상 사용하지 않는 폐기품을 다시 재사용하거나 폐기하는데 필요한 일련의 활동을 위한 역방향 로지스틱스에서의 수거망 설계 문제를 다루고 있다. 수거망 설계 문제는 수거지점의 위치와 수요지의 폐기품을 수거 지점에 할당하는 것을 결정하는 문제로 정의할 수 있으며 수거지점은 재활용품이나 폐기품이 위치한 지점 근처에 위치하고 주어진 잠재적인 위치를 중에서 결정하게 된다. 여기서, 각 수거지점은 용량제약이 있어 수거 지점에 할당되는 폐기품의 양에는 제한이 있다. 본 논문에서 다루는 수거망 설계문제에서는 수거지점을 설치하는데 필요한 고정비용과 수요지와 수거지점간의 수송비용의 합을 최소화하는 것을 목적으로 한다. 또한 대상문제를 보다 명확히 설명하기 위하여 징수계획법을 이용한 수리적 모형을 제안하였으며 문제의 복잡도 인하여 타부 서치와 시뮬레이티드 어닐링 두 가지 형태의 탐색기법을 제안하였다. 이들 탐색기법에 대하여 최대 500개의 잠재적 위치를 가지는 문제에 대하여 실험을 수행하였고 실험결과를 제시하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.64-64
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• 2021

댐의 중요 구성요소 중 하나인 여수로 구조물은 관행적으로 단위길이당 100m³/s 정도의 유량이 흐를 수 있도록 설계를 하고, 이를 초과할 때는 여수로 구조물에 피해가 가지 않도록 공기혼입 장치를 설치하거나 콘크리트의 설계강도를 증가시키는 대책을 사용하는 것이 일반적이다(댐설계 기준·해설, 2011) 그러나 건설된 지 오래된 댐의 경우 여수로 콘크리트 구조물의 설계강도가 낮고(최저 16.7MPa) 수문방류 횟수가 많아 최근에 건설된 댐 여수로 보다 상대적으로 많은 손상이 발생되어 있어 잦은 보수보강이 요구되고, 점차 유지관리 비용이 증대되고 있어 노후된 여수로 구조물일수록 기능을 유지하면서도 유지관리 비용을 절감할 수 있는 방안의 수립이 요구되고 있다. 이에 본 연구에서는 𐩒𐩒𐩒댐 여수로를 대상으로 2020년 홍수기 전·후의 여수로 바닥슬래브의 손상상태를 3D드론 매핑, 육안조사 및 내구성 조사결과 등을 이용한 정밀분석을 통해 수문방류시 여수로 바닥슬래브에 가장 큰 손상을 일으키는 손상메커니즘으로 유수에 의한 부상(uplift)에 의한 파손 메커니즘(Flow-driven uplift failure mechanism)을 제시하였으며, 여수로 바닥슬래브의 가장 일반적 손상원인으로 간주되고 있는 공동현상(cavitation)이 공동지수(cavitation index)가 0.3이상인 경우에도 발생할 수 있음을 확인하였다. 이와 같은 관찰 및 분석결과는 보다 많은 사례를 통하여 보완될 경우 향후 여수로 구조물의 설계 뿐만 아니라 보수보강 방법이나 유지관리, 더나아가서는 종합적 댐시설물 자산관리 계획을 수립하는데 매우 유용한 자산이 될 수 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.181-181
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• 2022

상수도 관망은 비정상상황에서도 안전한 물을 안정적으로 공급하는 것을 목표로 한다. 따라서 상수도 관망의 최적 설계는 수리학적 제약조건 (i.e., 절점의 압력, 관의 유속)을 만족하는 설계안을 제시한다. 하지만 점차 커지는 도시 규모에 따라 수질적으로 안전한 물을 공급하지 못하는 문제가 발생하고 있다. 또한, 상수도시스템의 형식 (i.e., 수지상식, 혼합식, 순환식)에 따라 용수의 체류 시간, 절점의 압력 등이 상이하다. 따라서, 본 연구에서는 도시 규모 및 형식과 잔류염소 농도를 고려한 상수도시스템 최적 설계를 진행하였다. 절점의 개수에 따라 도시의 규모를 분류하였으며, BI(BI; Branch Index) 지수를 통해 상수도시스템의 형식을 분류하였다. 또한, 수리학적 제약조건(i.e., 절점의 압력)과 수질적 제약조건 (i.e., 잔류염소 농도)을 설정하여 수리-수질을 동시에 만족하는 최적 설계안을 도출하였다. 비상시에도 물을 안정하게 공급하기 위하여 시스템의 탄력성과 설계비용을 목적함수로 설정하여 다목적 최적 설계를 진행하였다. 이러한 연구는 압력만을 고려한 기존 설계단계에서 수질적 측면을 동시에 고려하여 수질 측면의 안전성을 향상할 수 있다. 또한, 시스템의 탄력성을 고려하여 비정상상황에서도 물을 공급하여 사용성을 향상하는 설계안을 도출하여 수리학적 안정성을 만족하며, 경제적 측면도 향상할 수 있다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.1-9
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• 2012

This study proposed a method to determine the number and location of bus information terminals (BIT), which is a device to provide passengers with bus arrival time at bus stops in a Bus Information System (BIS). In low-density area, it is not efficient to survey bus demands such as the number of passengers at all bus stops due to time and cost. This kind of a survey would, however, competently cover all bus stops if performed inside the bus. The number of riding-on and -off passengers is observed for every bus stop, and this data collection is repeated over all day. Data obtained from the survey are aggregated each bus stop. This study defines Utility Index (UI), an aggregate each bus stop. Bus stops are ranked according to UI and determined for a BIT within budget limitation. As a case study, a bus line in Jeju island, Korea, was dealt with. This case showed that the more aggregate the better data quality. This study is expected to contribute to solving a location problem of BITs in a BIS.

• Korean Journal of Construction Engineering and Management
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• v.1 no.3 s.3
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• pp.101-107
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• 2000

On 1 July, 2000, the Ministry of Construction and Transportation announced the Earned Value Management System(EVMS) will be applied in public sector soon. However the arguments over the EVMS applied to our unique construction environment still exist and create strong concerns and worries among some experts it would be another mistakes proposed by the government. We do know the EVMS comes from C/SCSC which was first released by the United States Department of Defense in December 1967, and proved very powerful and efficient project management tool from a lot of practices. Although it is an excellent tool, we can not ignore our many experienced failures appling foreign system due to the differences of construction culture and law between the Korean and US construction industries. The purpose of the EVMS's success in Korea, therefore, this paper tests and proves the EVMS's adaptability and credibility to our construction environment by EAC model, that is one of the most important functions in the EVMS, using very scare EV data of the Korean construction projects.

• Journal of Korean Society of Forest Science
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• v.98 no.6
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• pp.726-732
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• 2009

In order to compare and analyze the international competitiveness of Non-Timber Forest Products, the analyses of Revealed Comparative Advantage, Market Comparative Advantage, and Constant Market Share were performed in this study. From the result of data analysis from 2002 to 2006, most of items lost the international competitiveness. In the case of chestnut, however, the RCA and MCA indices recently has decreased, but still shows the competitiveness. As a Non-Timber Forest Products show a weak international competitiveness, Import is expected to increased according to the pending FTA and DDA negotiations of Korea/China. Therefore, In order to elevate the international competitiveness, reinforcement of policy support to durable technical development is required to lower the production cost and to heighten the added value.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.981-986
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• 2015

As the seriousness of global environment pollution is gaining increasing public attention, research into greenhouse gas emissions of ships is being carried out globally. At a domestic level, however, in a number of significant fields such research has not been conducted to date. This study examined countermeasures for the reduction of $CO_2$ emission in the fields of electronic control engines, trim optimization, propeller polishing, hull cleaning, and anti-fouling paint using an actual sea-going vessel. Selected countermeasures were applied during sea trials of the ship and the effect of specific fuel oil consumption analyzed. It was found that each countermeasure resulted in a decrease of fuel consumption of 1~5%. The energy efficiency operational indicator (EEOI) was calculated and found to also be improved by 1~5%. Further research into the EEOI of domestic shipping is planned to enhance conformance with international environmental regulations and improve global competitiveness.