• 한국환경복원기술학회지
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• 제25권3호
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• pp.47-62
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• 2022

The Ministry of Environment has been working to reduce the impact on biodiversity, ecosystems, and social costs caused by soil runoff from highland Agricultural fields by setting up non-point pollution source management districts. To reduce soil loss, runoff path reduction technology has been applied, but it has been less cost effective. In addition, non-point pollution sources cause environmental conflicts in downstream areas, and recently highland Agricultural fields are becoming vulnerable to climate change. The Ministry of Environment is promoting the optimal management plan in earnest to convert arable land into forests and grasslands, but since non-point pollution is not a simple environmental problem, it is necessary to approach it from the aspect of NbS(Nature-Based Solution). In this study, a scenario for applying the nature-based solution was established for three subwatersheds west of Haean-myeon, Yanggu-gun, Gangwon-do. The soil loss distribution was spatialized through GeoWEPP and the amount of soil loss was compared for the non-point pollution reduction effect of mixed forests and grasslands. When cultivated land with a slope of 20% or more and ginseng fields were restored to perennial grasslands and mixed forests, non-point pollution reduction effects of about 32% and 29.000 tons compared to the current land use were shown. Also, it was confirmed that mixed forest rather than perennial grassland is an effective nature-based solution to reduce non-point pollution.

• 품질경영학회지
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• 제27권4호
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• pp.143-152
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• 1999

In Shewhart control chart, the average run length(ARL) is calculated using the mean of a conventional geometric distribution(CGD) assuming a sequence of identical and independent Bernoulli trials. In this, the success probability of CGB is the probability that any point exceeds the control limits. When the process is in-control state, there is no problem in the above assumption since the probability that any point exceeds the control limits does not change if the in-control state continues. However, if the out-of-control state begins and continues during the process, the probability of exceeding the control limits may take two forms. First, once the out-of-control state begins with exceeding probability p, it continues with the same exceeding probability p. Second, after the out-of-control state begins, the exceeding probabilities may very according to some pattern. In the first case, ARL is the mean of CGD with success probability p as usual. But in the second case, the assumption of a sequence of identical and independent Bernoulli trials is invalid and we can not use the mean of CGD as ARL. This paper concentrate on that point. By adopting one generalized binomial distribution(GBD) model that allows correlated Bernoulli trials, generalized geometric distribution(GGD) is defined and its mean is derived to find an alternative ARL when the process is in out-of-control state and the exceeding probabilities take the second form mentioned in the above. Small-scale simulation is performed to show how an alternative ARL works.

• 한국컴퓨터정보학회논문지
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• 제10권5호
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• pp.227-236
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• 2005

네트워크 이동성 기본 솔루션(NEMO basic solution)의 비 경로 최적화의 문제점을 해결하기 위한 방안 중 하나로 HPD(Hierarchical Prefix Delegation) 프로토콜이 있다. 그러나 HPD는 미시적 이동성에 대한 지원을 하지 못하므로 이동네트워크노드(MNN)가 접촉점을 변경할 때마다 MIPv6 프로토콜에서와 같이 HA(Home Agent)와 통신노드(CNs)로 BU(Binding Update) 메시지를 보내야하는 문제점을 갖는다. 본 논문은 HPD에 HMIPv6 프로토콜 개념을 적용하여 nested MEMO에서의 미시적 이동성을 효과적으로 지원하는 알고리즘을 제안하였다. 이동네트워크노드는 MAP(Mobility Anchor Point) 영역 안에서 위치변경 시 가까운 곳에 위치한 MAP으로만 BU를 보냄으로써 핸드오프 과정에서 발생하는 서비스 중단이나 신호 부하를 감소시켜 HPD에서의 한계를 극복하였다.

• 한국항공우주학회지
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• 제32권7호
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• pp.69-75
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• 2004

비행중인 다른 항공기를 회피하며 항공기를 목표점까지 유도하는 문제를 2차원 평면에서 고려하였다. 항공기는 속도의 크기가 일정한 질점이며, 제어입력으로 측가속도를 사용하는 것으로 가정하였다. 이동장애물에는 척력 포텐셜함수를 목적점에는 인력 포텐셜함수를 인공적으로 부여하여 항공기에 척력과 인력이 작용하도록 하였다. 유도/회피명령은 이들 포텐셜력과 상대속도를 사용하여 실시간으로 구현 가능한 유도/회피법칙을 구현하였다. Log 형태의 포텐셜함수를 사용하면 구현된 유도법칙은 잘 알려진 비례항법유도법칙이 되며, 회피법칙은 장애물까지 도달시간에 반비례하고 시선각 변화의 반대 방향으로 항공기를 회전시킨다. 제안된 유도/회피법칙은 시뮬레이션을 통하여 타당성을 검증하였다.

• 한국컴퓨터정보학회논문지
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• 제11권1호
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• pp.147-155
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• 2006

네트워크 이동성 기본 솔루션(NEMO basic solution)의 비 경로 최적화의 문제점을 해결하기 위한 방안 중 하나로 HPD(Hierarchical Prefix Delegation) 프로토콜이 있다. 그러나 HPD는 미시적 이동성에 대한 지원을 하지 못하므로 이동네트워크노드(MNN)가 접촉점을 변경할 때마다 MIPv6 프로토콜에서와 같이 HA(Home Agent)와 통신노드(CNs)로 BU(Binding Update) 메시지를 보내야하는 문제점을 갖는다. 본 논문은 HPD에 HMIPv6 프로토콜 개념을 적용하여 nested NEMO에서의 미시적 이동성을 효과적으로 지원하는 알고리즘을 제안하였다. 이동네트워크노드는 MAP(Mobility Anchor Point) 영역 안에서 위치변경 시 가까운 곳에 위치한 MAP으로만 BU를 보냄으로써 핸드오프 과정에서 발생하는 서비스 중단이나 신호 부하를 감소시켜 HPD에서의 한계를 극복하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권3호
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• pp.1047-1062
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• 2022

Differential power analysis (DPA) is disturbed by ghost peaks. There is a phenomenon that the mean absolute difference (MAD) value of the wrong key is higher than the correct key. We propose a compressed key guessing space (CKGS) scheme to solve this problem and analyze the AES algorithm. The DPA based on this scheme is named CKGS-DPA. Unlike traditional DPA, the CKGS-DPA uses two power leakage points for a combined attack. The first power leakage point is used to determine the key candidate interval, and the second is used for the final attack. First, we study the law of MAD values distribution when the attack point is AddRoundKey and explain why this point is not suitable for DPA. According to this law, we modify the selection function to change the distribution of MAD values. Then a key-related value screening algorithm is proposed to obtain key information. Finally, we construct two key candidate intervals of size 16 and reduce the key guessing space of the SubBytes attack from 256 to 32. Simulation experimental results show that CKGS-DPA reduces the power traces demand by 25% compared with DPA. Experiments performed on the ASCAD dataset show that CKGS-DPA reduces the power traces demand by at least 41% compared with DPA.

• 한국정밀공학회지
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• 제12권4호
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• pp.67-77
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• 1995

In modern industry the requirement of automation of manufacturing process increases so that unmanned system has been popular as an ultimate goal of modern manufacturing process. In unmanned manufacturing process the tool fracture is a very serious problem because it results in the damage of workpieces and can stop the operation of whole manufa- turing system. In this study, image processing technique is used to detect the fracture of insert tip of face milling using multi-point-tool. In order to acquire the image information of fracture shape of rotation insert tip. We set up the optical system using a light beam chopper. In this system we can reduce the image degradation generated from stopped image of rotating insert tip using image restoration technique. We calculated the mean square error to diagnose the condition of tool fracture, and determind the criteria of tool fracture using experimental and staticstical method. From the results of this study we've developed non- contact detection technique of tool fracture using image processing method and proposed the fracture direction of automation and unmanned system considering the optimal time of tool change milling.

• 한국간호교육학회지
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• 제3권
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• pp.26-33
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• 1997

Problem-Based Learning(PBL) is at the forefront of educational reform. The acceptance of PBL as an educational approach with wide application represents a major change in thinking about educational processes and their relationships to the wider community. In 1969, PBL as a method was introduced at the Medical School of McMaster University in Hamilton, Canada. The most important advantages in PBL are acquiring knowledge that can be retrieved and applied, learning to learn(self-directed learning) and learning to analyze and solve Problems. PBL is widely used within the sector where it had its origin, namely health profession education. A generally accepted starting point in the development of a problem-based curriculum is the set of professional competencies of future graduates, which describe the typical problems professionals have to deal with. Formulating learning objectives highly depends on the format and content of the presented problems. Contrary to that, in a classic course in higher education, it is customary that teachers express objectives in a compulsory subject matter. Curricula which advocate problem-based learning generally use case studies in the form of paper cases, simulations and real patients with the intention of stimulating classroom discussion of clinical and basic science concepts within a problem-solving framework. One goal of using paper cases is to stimulate the learning of basic science within a clinical situation. Through self-directed study the students solve problems and explore the psycho-social dimensions within the cases. The general outcome based on the program evaluation research of PBL is that PBL students respond positively about the learning experience. In summary, PBL is a curriculum design and a teaching/learning strategy which simultaneously develops higher order thinking and disciplinary knowledge bases and skills by placing students in the active role of practitioners(or problem solvers) confronted with a situation(ill-structured problem) which reflects the real world.

• 대한수학회지
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• 제52권4호
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• pp.765-780
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• 2015

We consider the problem of characterizing the palindromic sequences ${\langle}c_{d-1},\;c_{d-2}\;,{\cdots},\;c_0\rangle$, $c_{d-1}{\neq}0$, having the property that for any $K{\in}\mathbb{N}$ there exists a number that is a palindrome simultaneously in K different bases, with ${\langle}c_{d-1},\;c_{d-2}\;,{\cdots},\;c_0\rangle$ being its digit sequence in one of those bases. Since each number is trivially a palindrome in all bases greater than itself, we impose the restriction that only palindromes with at least two digits are taken into account. We further consider a related problem, where we count only palindromes with a fixed number of digits (that is, d). The first problem turns out not to be very hard; we show that all the palindromic sequences have the required property, even with the additional point that we can actually restrict the counted palindromes to have at least d digits. The second one is quite tougher; we show that all the palindromic sequences of length d = 3 have the required property (and the same holds for d = 2, based on some earlier results), while for larger values of d we present some arguments showing that this tendency is quite likely to change.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 춘계학술대회
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• pp.861-863
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• 2014

실내 위치 기반 서비스를 위한 대표적인 위치 추정 시스템으로 fingerprinting 기법이 존재하지만 fingerprinting map을 구축하는 시간이 오래 걸리는 문제가 있으며, 이러한 문제를 해결하기 위해 유사한 공간에서 WAP(wireless access point)의 수신신호가 항상 유사하다는 것을 증명해야한다. 본 논문에서는 WAP의 수신신호 데이터를 이용한 fingerprinting map을 구성할 수 있는 방안을 제안한다. 이를 위해 같은 공간에서 WAP의 위치를 변경하며 그에 따른 거리 대 RSSI 변화 추이를 확인하였으며, 유사한 공간의 다른 지점에서 수집한 RSSI가 유사하게 변화는 것을 확인하였다.