• Journal of Navigation and Port Research
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• v.38 no.2
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• pp.105-110
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• 2014

Korean government sets up a goal that jumps up to the third ranked powerful nation of offshore wind in the world until 2020 and announced "The plan for 2.5-gigawatt wind farm off the south-west coast by 2019". Such above, according to green energy policy, offshore wind farms(OWF) will be increased continuously. The development of OWF should be taken account of wind volume as well as marine traffic environment. Specially aids to navigation of OWF play a significant role in preventing collision between vessels navigating near waters and structures. For purpose of distinguishing OWF, IALA recommendations define installation of lights on SPS and IPS. However, there is no mention of light character that plays important role in identification of lights as marking offshore wind farm. Also the research on selection of proper light character has been insufficient state. Therefore in this paper, we analyzed internal and external regulations concerned marking with light on SPS and IPS in OWF. And suggested patterns and rhythms of light having not only easily recognized feature but also no confusion with other light of aids to navigation. The proposed light characters were verified by simulation, and the results were analysed that synchronism flickering of "Fl Y(4) 12s(SPS)" and "Fl Y 6s(IPS)" would be useful in combination of both lights.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.307-323
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• 2003

In this study the pilot test of C.G.S (Compaction Grouting System) as injection method by low slump mortar was performed and the results were analyzed in order to find out the application of this method to the soft ground and the effect of settlement restraint. The site for pilot test is adjacent to apartments supported by pile foundations. Sand drain method was performed previously as countermeasures against settlement, but settlement occurs continuously because this ground is very soft. Site investigations such as SPT, CPT and vane shear test were performed to determine the characteristics of ground improvement after the installation of C.G.S. Field measurements were performed on purpose to find out the displacement of ground during the installation of C.G.S. From the results of this study, C.G.S method can be optimized by the control of radius, space, depth, injection material and injection pressure. C.G.S improves soft ground with radial consolidation of adjacent soft ground. Considering that increase of N value to about 3, C.G.S can be considered as an effective method to increase the bearing capacity as well as constrain the settlement of soft ground. It is also expected to be economic and effective in the improvement of ground when it is used in applicable sites.

• 한국HCI학회:학술대회논문집
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• 2007.02b
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• pp.651-655
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• 2007

카툰 렌더링 그래픽을 기반으로 한 온라인 RPG 게임인 마비노기에서는 게임이용자들이 염색 시스템을 통하여 의복아이템에 자신들이 원하는 색을 자유롭게 표현할 수 있다. 마비노기에서 색에 관련된 주목할 만한 현상은유행색이 존재하고 색에 따라 같은 아이템의 가격이 달라진다는 점이다. 유행색이 존재하는 것은 현실과 비슷하지만 같은 아이템이 색에 따라 가격이 달라지는 것은 현실에서는 보기 드물다. 이는 현실과 비슷하면서도 심리적인 속성이 다른 사이버공간만의 특징이라고 생각해 볼 수 있다. 따라서 마비노기에서 게임이용자들이 색을 선택하고 사용할 때 작용하는 심리기제가 존재할 것이라고 가정해 볼 수 있다. 이에 본 연구에서는 마비노기에서 색 선택 행동의 심리적 유형을 확인하고 유형별 특징을 알아보기 위해 자아존중감을 측정하였다. 예비 조사를 통해 게임이용자 20명과 온라인 인터뷰를 실시하여 색 사용 경험을 추출하고, 추출한 경험을 바탕으로 18문항의 색 선택 행동 문항을 구성하였다. 본 조사에서는 온라인 설문으로 129명의 게임이용자를 대상으로 색 선택 행동과 자아존중감을 측정하였다. 연구 결과 색 선택 행동은 4개의 요인-색채 둔감성, 유행추종, 개성표현, 캐릭터이미지와의 적합성-으로 구분되었다. 색선택 행동 4개의 하위 요인을 기준으로 군집분석한 결과 색 선택 행동 유형은 각각 색 분화형, 유행추종형, 색 둔감형으로 구분되었다. 색 선택 행동 유형과 자아존중감과의 관계에서는 자아존중감 하위 범주 중 부정적인 자기평가, 타인의 의견에 대한 걱정, 의존성의 세 가지 하위 범주에서 색 선택 행동 유형에 따른 차이가 유의미하게 나타났다. 한편 자의식 차원에서는 색 선택 행동 유형간 유의미한 차이가 발견되지 않았다. 유행추종형은 다른 두 유형에 비해 상대적으로 자아존중감 수준이 낮음을 확인할 수 있었다. 반대로 색 둔감형은 다른 두 유형에 비해 상대적으로 자아 존중감 수준이 높았다. 색 분화형은 유행추종형과 색 둔감형의 중간 수준의 자아존중감을 볼 수 있었다. 유행추종형은 자기의 외부에서, 색 둔감형은 자기의 내부에서 색과 관련된 자신에 대한 가치감의 소재와 근원을 찾는 특성이 있다고 해석할 수 있다. 본 연구는 온라인 RPG 게임에서 게임이용자들의 색 선택의 심리적 기제를 확인하고 색 선택 유형별로 자아존중감과의 관계를 확인함으로써 색 선택 행동의 심리적 기제를 밝히려는 기초연구라는 점에 의의가 있다. 추후에는 게임이용자들의 색 선택 행동을 보다 포괄적으로 이해하기 위해 게임이용자들이 가지고 있는 공통적인 색이미지와 개별적인 색이미지 및 색이미지의 심리적 구조를 알아보기 위한 색채감성연구가 필요할 것이다. 이러한 연구들은 게임을 제작할 때 캐릭터 디자인과 아이템 디자인에 어떠한 색을 사용해야 되는지 방향을 설정하는데 도움을 줄 수 있을 것이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1153-1160
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• 2005

OFDM/OQAM(Offset QAM)-IOTA system requires the IOTA(Isotropic Orthogonal Transform Algorithm) function that has superior localization property in time and frequency domain instead of guard interval used for conventional OFDM/QAM system to be robust to multipath channel. Therefore, OFDM/OQAM-IOTA system has more spectral efficiency than conventional OFDM/QAM system. But, when channel estimation scheme for conventional OFDM/QAM system is applied straightforwardly to OFDM/OQAM-IOTA system, an intrinsic Inter- symbol-Interference is observed. So suitable preamble structure for the channel estimation scheme of OFDM/OQAM-IOTA system is required. In this paper, we propose a new preamble structure that is appropriate to OPDM/OQAM-IOTA system and then perform ideal channel estimation and practical channel estimation in low-to-medium mobile speed and compare them with conventional OFDM/QAM system. Simulation results show that OFDM/OQAM-IOTA system with proposed preamble structure has 1.5 dB Eb/NO gain on Target BER $10^{-3}$ and about $25\%$ transmission rate gain against the conventional OFDM/QAM system considering quarter of FFT size as guard interval size.

• KSBB Journal
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• v.28 no.5
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• pp.287-294
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• 2013

Stained and discolored hair will be damaged by the shampooing, daily UV disposal, and the use of hair dryer. Thus many studies about the effect of various natural substances on the re-secure the skin and scalp are recently reported. This study was carried out to investigate the effect of green tea (Camelloia sinensis) seed oil on colored (dyed) and decolored (bleached) hair. The beneficial effects of green tea seed oil are already well known, but little research has been done about the hair treatment and fade-resistant effect. Dyed and bleached hair was pretreated with green tea seed oil to determine the tensile strength and elongation of the hair, to analyze the hair surface using SEM, and to compare the color fade using spectrocolormeter. The results showed that the tensile strength increased with green tea seed oil pretreatment samples for virgin, dyed, and bleached hairs. Elongation showed the reverse results showing the presence of hair treatment effect. The results of the surface pre-treatment in all groups analyzed by SEM, the hair cuticle became sharper, so coating effect were identified with all samples. The value of the $L^*$, $a^*$, $b^*$ decreased with washed hairs damaged by UV irradiation and the values were decreased also in dyed and bleached hair. In summary, green tea seed oil prevent reinjury to the heat and UV rays for colored and decolored hairs. Cosmetic practice effects of the oil were identified in the field to be appropriate to the customer's skin and scalp that natural cosmetic oils would like to offer.

• Korean Journal of Construction Engineering and Management
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• v.12 no.5
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• pp.146-154
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• 2011

Korean contractors have been maintained sustainable growth since entering into overseas construction market for the first time in 1960' s. In 2010, Korean contractors ordered 761 billion (USD) from overseas markets. Especially, billion (USD) were earned by Korean contractors in overseas plant construction market which account for more than 80% of the total amount by Korean contractors. Nevertheless, many Korean contractors are suffering from lack of technological competitiveness and construction management skills in the design phase compared with global leading contractors. These conditions have directly effect on the success of projects in terms of cost, duration, and quality. So, this study focused on identifying the risk factors and developing risk priority method for the design phase of LNG plant projects whose market is expanding. Research procedures were conducted by the following three steps. First, total 57 risk factors were identified in design phase through extensive literature reviews and experts survey. Second, the authors developed risk priority method which are more suitable for design phase of LNG plant projects by using three criteria, Probability(P), Impact(I), and Coordination Index(CI). Finally, the suitability of risk priority method and practical applicability were verified through expert survey and interview. Consequently, if korean contractors use the suggested risk factors and priority method based on their own know-how and experiences, then more reasonable and rational risk management will be conducted in the design phase of LNG plant projects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.12
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• pp.831-841
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• 2014

The attacker can access the RFID systems illegally because authentication operation on the RFID systems are performed in wireless communication. Authentication methods based on the PUF were presented to defend attacks. Because of Hash and AES, the cost is expensive for the low-cost RFID tag. In this paper, the PUF-based encryption processor and the mutual authentication protocol are proposed for low-cost RFID authentication. The challenge-response pairs (PUF's input and output) are utilized as the authentication key and encrypted by the PUF's characteristics. The encryption method is changed each session and XOR operation with random number is utilized. Therefore, it is difficult for the attacker to analyze challenge-response pairs and attack the systems. In addition, the proposed method with PUF is strong against physical attacks. And the method protects the tag cloning attack by physical attacks because there is no authentication data in the tag. Proposed processor is implemented at low cost with small footprint and low power.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.7
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• pp.479-490
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• 2014

A lower extremity exoskeleton is a robot device that attaches to the lower limbs of the human body to augment or assist with the walking ability of the wearer. In order to improve the wearer's walking ability, the robot senses the wearer's walking locomotion and classifies it into a gait-phase state, after which it drives the appropriate robot motions for each state using its actuators. This paper presents a method by which the robot senses the wearer's locomotion along with a novel classification algorithm which classifies the sensed data as a gait-phase state. The robot determines its control mode using this gait-phase information. If erroneous information is delivered, the robot will fail to improve the walking ability or will bring some discomfort to the wearer. Therefore, it is necessary for the algorithm constantly to classify the correct gait-phase information. However, our device for sensing a human's locomotion has very sensitive characteristics sufficient for it to detect small movements. With only simple logic like a threshold-based classification, it is difficult to deliver the correct information continually. In order to overcome this and provide correct information in a timely manner, a probabilistic gait-phase classification algorithm is proposed. Experimental results demonstrate that the proposed algorithm offers excellent accuracy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.206-206
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• 2008

압전소자를 이용한 초음파 모터는 전자기적 원리로 동작하는 기존의 모터에 비해 구조가 간단하고 소형, 경량화가 가능하며 저속에서 큰 토크가 가능하고 ${\mu}m$단위 까지 정밀제어가 가능하다는 장점 등으로 인해 그 응용분야가 점차 확대되고 있다. 초음파 모터의 원리는 수평과 수직방향에서 변위가 타원형 운동을 형성하는 것이다. 따라서 선택한 타원운동의 방식에 의해서 모터의 형상이 달라진다. 초음파 모터는 액츄에이터를 사용하여 만들기 때문에 액츄에이터의 특성은 모터의 타원변위나 토크에 영향을 미친다. 단판형 액츄에이터에 비하여 적층 액츄에이터는 입력 임피던스를 낮추어 낮은 구동전압에서 구동이 가능하며 큰 변위와 토크를 발생하기 때문에 진동자의 수명 향상과 구동전압을 낮추기에 적합하다. 적층 액츄에이터는 변위량이나 응력 등을 개선하기 위해서 전기기계 결합계수(kp) 및 압전 d상수가 큰 재료가 요구되며, 고전압에서 장시간 구동 시 마찰에 의한 열손실을 감소시키기 위해 높은 기계적 품질계수(Qm)를 가져야한다. 적층 시 내부전극으로 사용하는 Pd, Pt가 함유된 전극은 가격이 비싸 제조비용을 상승시킨다. 상대적으로 값싼 Ag전극을 사용하면 비용절감을 할 수 있지만 융점이 낮아서 저온소결이 불가피하다. 따라서, 특성이 우수한 적층 액츄에이터를 제조하기 위해서 저손실, 저온소결 할 수 있는 액츄에이터 재료가 필요한 실정이다. L1-B4 혈 선혈 초음파 모터는 L1모드와 B4모드의 공진 주파수가 일치하여야 큰 변위를 얻을 수 있는데 이전의 논문에서 Atila를 이용한 시뮬레이션 결과를 분석한 봐 있다. 적층 액츄에이터의 층수를 5,7,9,11,13,15층으로 하여 L1-B4모드에서의 공진주파수를 비교한 결과 13 층일 때 두 모드가 비슷한 공진주파수를 보였고, 티원변위궤적도 다른 층수에 비해 크게 나타났다. 본 연구에서는 시뮬레이션 결과 가장 좋은 특성을 보인 13층 액츄에이터로 선형 초음파 모터를 제작하였다. 또한, 액츄에이터는 압전 및 유전특성이 우수한 저온소결 PZW-PMN-PZT세라믹을 이용하여 제작하였고, 내부전극으로 Ag전극을 사용하였다. 제작된 13 층 선형초음파모터를 가지고 프리로드 및 전압에 따른 속도를 조사하였고, 시뮬레이션 결과와 비교해 보았다.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.341-348
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• 2016

At present, about 40 million tons of concrete is dismantled each year, which accounts for the largest portion of the total amount of construction waste with 60.8%. It is known about 97.5% of it is recycled. However, most of the usage of waste concrete is limited to lower value-added business areas, and considering the increasing amount of waste concrete generated due to the deterioration of structures, the need for converting waste concrete to structural concrete is urgent. Therefore, this study aims at estimating the period for the optimum carbonation reforming to improve the quality of recycled aggregate, by making use of the method of accelerated carbonation reforming of the bonding heterogeneous (cement paste and mortar) for the purpose of converting recycled aggregate to structural concrete. Based on the period appropriate for the heterogeneous thickness and each bonding thickness of recycled aggregate which was drawn from previous studies, the changes in the characteristics and physical properties of pore structure according to progress of accelerated carbonation were analyzed. The result shows that with the progress of carbonation, the pore volume and the percentage of water absorption of the bonding heterogeneous decreased and the density increased, which indicates improvement of the product quality. But after certain age, the tendency was reversed and the product quality deteriorated. Synthesizing the results of previous studies and those of the present study, this study proposed 4 days and 14 days respectively for the period for the optimum carbonation reforming of recycled fine aggregate and recycled coarse aggregate.