• Smart Structures and Systems
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• 제22권1호
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• pp.81-94
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• 2018

Automatic Generation Control (AGC) has functionally controlled the interchange power flow in order to suppress the dynamic oscillations of frequency and tie-line power deviations as a perturbation occurs in the interconnected multi-area power system. Furthermore, Flexible AC Transmission Systems (FACTS) can effectively assist AGC to more enhance the dynamic stability of power system. So, Static Synchronous Series Compensator (SSSC), one of the well-known FACTS devices, is here applied to accurately control and regulate the load frequency of multi-area multi-source interconnected power system. The research and efforts made in this regard have caused to introduce the Fractional Order Proportional Integral Derivative (FOPID) based SSSC, to alleviate both the most significant issues in multi-area interconnected power systems i.e., frequency and tie-line power deviations. Due to multi-objective nature of aforementioned problem, suppression of the frequency and tie-line power deviations is formularized in the form of a multi-object problem. Considering the high performance of Multi Objective Bees Algorithm (MOBA) in solution of the non-linear objectives, it has been utilized to appropriately unravel the optimization problem. To verify and validate the dynamic performance of self-defined FOPID-SSSC, it has been thoroughly evaluated in three different multi-area interconnected power systems. Meanwhile, the dynamic performance of FOPID-SSSC has been accurately compared with a conventional controller based SSSC while the power systems are affected by different Step Load Perturbations (SLPs). Eventually, the simulation results of all three power systems have transparently demonstrated the dynamic performance of FOPID-SSSC to significantly suppress the frequency and tie-line power deviations as compared to conventional controller based SSSC.

• 사물인터넷융복합논문지
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• 제3권1호
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• pp.13-19
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• 2017

본 논문에서 저전력 장거리 무선통신기술(LPWA) 기반으로 원격감시 및 제어가 가능한 자가설치형 농업 자동화 시스템 "씽커넥트-Green" 을 설계 및 구현하였다. 영농을 위해서는 물, 햇빛, 흙, 비료, 온도 조절 등이 필요하며 이러한 요소들을 자동화된 시스템을 이용하여 원격 모니터링 및 제어할 수 있다. 본 시스템을 이용하여 비닐하우스부터 화훼단지에 이르기까지 식물의 종류와 재배 환경에 따라 최적화하여 구축할 수 있는 농업 자동화 시스템을 구축할 수 있다. 센서로부터 수집된 정보는 게이트웨이를 통해 서버에 저장되며, 빅데이터를 토대로 스마트폰을 이용하여 최적화된 재배 환경을 설정 및 운영할 수 있다.

• 한국식생활문화학회지
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• 제12권1호
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• pp.87-96
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• 1997

The purpose of this study is, to examine current foodservice management practices at free meal service organization for elderly people and, to evaluate the attitude of recipients about the service and their ecological background. 6 meal service center as well as randomly selected 120 recipients at Sungnam area were surveyed and interviewed and result were summarized as follow. The cost of each meal (lunch) was ranged from 1,300 won to 1,500 won and number of attendant at meal service were ranged from 50 to 200 persons. Meal time for lunch begins from 10:30 am to noon because greater portion of people (elderly) didn't take breakfast frequently. Most of the center adapted self-service system. Standard recipe was not developed and meal preparation was controlled under the experiences of volunteer’s. Recording system of, nutrition management, production control, storage and inventory control was not well adapted by most of the center. In order to measure the level of storage, sanitation etc., scorin system in survey was adapted in this study and result are as follow: The score of sanitation of kitchen was lower than dinning area and that of food storage was lowest score. It was suggested that not only financial but also systematical support on management by local government may be necessary to meet the goal of supply nutritionally balanced food at the center. The score given by the recipient on the satisfaction of meal service was rate as 4.8 at the 5-point maximum scale. Meeting friends and share social relationship was major reason (41.6% of the total) of visiting to the center. It is suggested that in order to meet the changes of the patterns of change of social and family structure, the service of the center should be extended in urban area and it is necessary to develop systematic management models for the center.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2479-2484
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• 2018

The filter bank multicarrier modulation (FBMC) technique is one of multicarrier modulation technique (MCM), which is mainly used to improve channel capacity of cognitive radio (CR) network and frequency spectrum access technique. The existing FBMC System contains serial to parallel converter, normal QAM modulation, Radix2 inverse FFT, parallel to serial converter and poly phase filter. It needs high area, delay and power consumption. To further reduce the area, delay and power of FBMC structure, a new clock gating technique is applied in the QAM modulation, radix2 multipath delay commutator (R2MDC) based inverse FFT and unified addition and subtraction (UAS) based FIR filter with parallel asynchronous self time adder (PASTA). The clock gating technique is mainly used to reduce the unwanted clock switching activity. The clock gating is nothing but clock signal of flip-flops is controlled by gate (i.e.) AND gate. Hence speed is high and power consumption is low. The comparison between existing QAM and proposed QAM with clock gating technique is carried out to analyze the results. Conversely, the proposed inverse R2MDC FFT with clock gating technique is compared with the existing radix2 inverse FFT. Also the comparison between existing poly phase filter and proposed UAS based FIR filter with PASTA adder is carried out to analyze the performance, area and power consumption individually. The proposed FBMC with clock gating technique offers low power and high speed than the existing FBMC structures.

• Journal of Biosystems Engineering
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• 제41권1호
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• pp.12-20
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• 2016

Purpose: Pepper prices have risen continuously because of a decrease in cultivation area; therefore, mechanical harvesting systems for peppers should be developed to reduce cost, time, and labor during harvest. In this study, a screw type picking head for a self-propelled pepper harvester was developed, and the optimal working conditions were evaluated considering helix types, winding directions of helix, and rotational speeds of the helix. Methods: The screw type was selected for the picking head after analyzing previous studies, and the device consisted of helices and a feed chain mechanism for conveying pepper branches. A double helix and a triple helix were manufactured, and rotational speeds of 200, 300, and 400 rpm were tested. The device was controlled by a variable speed (VS) motor and an inverter. Both the forward and reverse directions were tested for the winding and rotating directions of the helix. An experiment crop (cultivar: Longgreenmat) was cultivated in a plastic greenhouse. The test results were analyzed using the SAS program with ANOVA to examine the relationship between each factor and the performance of the picking head. Results: The results of the double and triple helix tests in the reverse direction showed gross harvest efficiency levels of 60-95%, mechanical damage rates of 8-20%, and net marketable portion rates of 50-80%. The dividing ratio was highest at a rotational speed of 400 rpm. Gross harvest efficiency was influenced by the types of helix and rotational speed. Net marketable portion was influenced by rotational speed but not influenced by the type of helix. Mechanical damage was not influenced by the type of helix or rotational speed. Conclusions: Best gross harvest efficiency was obtained at a rotational speed of 400 rpm; however, operating the device at that speed resulted in vibration, which should be reduced.

• 대한간호학회지
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• 제47권6호
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• pp.756-769
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• 2017

Purpose: To identify the effects of a smart program for the patients who underwent percutaneous coronary intervention (SP-PCI) on coronary disease-related knowledge, health behaviors, and quality of life. Methods: A nonequivalent control group with a non-synchronized design was utilized and 48 participants (experimental=22, control=26) were recruited from a university hospital in Gyeongsang area from May to December, 2016. The 12-week SP-PCI consisted of self-study of health information using smart phone applications (1/week), walking exercise (>5/week) using smart band, feedback using Kakao talk (2/week), and telephone counseling (1/week). Patients in the control group received usual care from their primary health care providers and a brief health education with basic self-management brochure after the PCI. Data were analyzed using the SPSS 21.0 program through descriptive statistics, $x^2$ test, and t-test. Results: After the 12-week SP-PCI, the experimental group showed higher levels of coronary disease-related knowledge (t=2.43, p=.019), heart-related health behaviors (t=5.96, p<.001), regular exercise (Z=-4.47, p<.001), and quality of life-MCS (t=3.04, p=.004) and showed lower levels of stress (Z=-3.53, p<.001) and sodium intake (t=-4.43, p<.001) than those in the control group. There were no significant group differences in medication adherence and food intake in total energy, lipids, and cholesterol. Conclusion: The suggested SP-PCI provided easy access and cost-effective intervention for patients after PCI and improved their knowledge of the disease, performance of health behaviors, and quality of life. Further study with a wider population is needed to evaluate the effects of SP-PCI on disease recurrence and quality of life for patients after PCI.

• 한국농림기상학회지
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• 제21권1호
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• pp.1-28
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• 2019

본 연구에서는 한라산 사방향에 분포하는 구상나무 자생지 중 9개 조사구에 대하여 구상나무를 생목과 사목으로 구분하여 도면화하고, 그 밀도와 고사율을 분석하였다. 분석 결과, 구상나무는 조사구 내의 위치에 따라 밀도 및 고사율에 있어 상당한 불균질성을 보였다. 이는 위치에 따라 변화하는 특정 인자가 구상나무 고사를 발생시킬 것이라는 추정을 가능케 한다. 본 연구에서는 구상나무 밀도 및 고사율을 토대로 고도, 지형경사, 수계망, 일사량과 경사향 등의 지형적 요인과 구상나무 고사현상과의 관련성을 살펴보았다. 구상나무는 고도가 증가함에 따라 밀도가 증가하였으며, 고사율 또한 증가하였다. 지형경사와 고사율 사이에는 음의 상관관계가 인지되었으며, 수계망이 미약하게 발달한 완만한 곳에서 고사율이 높게 나타났다. 그리고 경사향에 따라 고사율이 크게 변화하는 것이 인지되었으며, 생목이 우세한 영역이 사목이 우세한 영역에 비해 평균 일사량이 많게 나타났다. 전반적으로 한라산 구상나무는 상대적으로 지형경사가 완만하고, 일사량이 적은 곳에서 많이 고사하는 것으로 나타났다. 지형경사가 완만할수록 상대적으로 토양수분 함량이 많고, 일사량이 적을수록 증발량이 적어져 토양수분 함량이 많다는 기존 연구결과를 고려하면, 토양수분 과다가 한라산 구상나무 고사의 원인으로 추정된다. 이는 근래의 한반도 및 제주 지역에서 나타나는 강수량 증가, 증발량 감소, 일조시간 감소 등의 일련의 기후변화 현상, 한라산 고도 증가에 따른 강수량 증가와 함께 나타나는 고사율 증가현상, 한라산 아고산지대에서의 식생변화 등의 증거들에 의해 뒷받침된다. 이번 연구에서 고도 및 지역에 따라 인지되는 구상나무 밀도와 고사율의 변화양상은 향후 구상나무 쇠퇴현상에 대한 수치 모델링 연구에 있어 공간변수로 활용될 수 있을 것으로 기대한다. 뿐만 아니라, 정사항공영상을 활용하는 개체단위의 수목분포 조사 방법은 향후 장기적 식생변화 연구에 있어 수치적 모니터링 기법으로 널리 활용될 수 있을 것이다.

• 한국포장학회지
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• 제29권2호
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• pp.111-118
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• 2023

본 연구에서 연속형 레이저와 나노초 레이저의 경우에는 고분자와 물성 조건이 맞지 않아서, 고분자 필름 표면에 특정 패터닝이 구현되지 않았다. 그러나, 펨토초 레이저를 활용하여 HDPE, PP, PET 등의 식품포장 필름의 표면에 패터닝이 구현됨을 확인하였다. 따라서, 본 연구에서 식품포장 필름에서 펨토초 레이저 패터닝 공정 조건을 확립하였고, 싱글 펄스에 의한 대면적 원형 패턴, 싱글 펄스를 30%를 중첩한 대면적 거칠기 패턴, 직선 패턴, 직선 패터닝을 중첩한 대면적 거칠기 패턴, 직선 패터닝을 교차하여 격자 패턴 등의 표면 패터닝 필름을 제작하였다. 또한, 표면 패턴 구조와 크기에 따른 패터닝 HDPE, PP, PET 필름은 SEM, AFM, 접촉각 분석을 통하여 그 특성을 확인하였다. 펨토초 레이저 패터닝을 하지 않은 각 대조군 필름의 표면 대비 대면적 원형 패터닝 HDPE 및 PP 필름, 싱글 펄스를 30%를 중첩한 대면적 거칠기 패터닝 및 직선 패터닝을 중첩한 대면적 거칠기 패터닝 PET 필름의 표면은 27.1-37.5°의 접촉각을 나타냄으로써, 패터닝 후에 HDPE, PP, PET 필름은 친수성 표면으로 변화되었다. 반면, 나노-마이크로 크기의 돌기 표면구조를 갖고 있는 대면적 격자 패터닝 HDPE 필름의 경우에는 120.4°의 접촉각을 보임으로써, 패터닝 후에 소수성 표면으로 변화되었다. 따라서, 패터닝을 통해 친수성 표면으로 바뀐 필름들은 단백질, 세포, 바이러스 등을 비롯하여 식품의 물질들이 달라붙지 못하거나, 쉽게 떨어지는 엔티파울링 응용분야에 활용이 가능하다. 또한, 향후 좀더 정밀한 나노 및 마이크로 돌기 구조를 갖는 격자 패터닝을 통해 150° 이상의 초소수성 표면을 제작하게 된다면, 자가 청소(Self-cleaning) 등의 초소수성 표면 응용분야에 활용 가능할 것이다.

• 한국HCI학회논문지
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• 제14권2호
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• pp.49-60
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• 2019

자율주행차량에서 전기자동차의 등장까지 자동차 산업은 급속도로 변화하고 있다. 이러한 변화 속에서 운전자가 자동차를 어떻게 제어하고 안전과 편의를 얻을 것인가에 대한 HMI 연구는 더욱 중요해지고 있다. 본 연구는 차량 제조사들이 어떠한 관점으로 주행상황을 이해하고 있으며, 운전자의 인터랙션을 어떻게 정의하고 한계 짓는가에 대해 이해하고자 하였다. 이를 위해 HMI에 대한 선행 연구를 리뷰하였으며, 15인의 참가자가 직접 5개 제조사의 차량을 실제 도로에서 운전하고 인터페이스를 사용해보는 온로드 연구를 수행하였다. 연구 결과를 통해 본 연구는 주행 중 운전자가 쉽게 제어할 수 있는 버튼과 스위치 류가 제조사별로 상이했으며, 주행 중 보다 집중적으로 제어할 수 있는 버튼과 제어하기에 어려운 버튼이 존재함을 확인하였다. Audi 차량은 '컨트롤러의 선택과 집중', BMW 차량은 '드라이빙 중심의 최적화', Benz의 차량은 '단순화와 최소화', Lexus의 차량은 '조작분산의 제거', KIA의 차량은 '시각적 안정감'을 HMI의 특징적 키워드로 도출할 수 있었다. 이것은 각 제조사들이 운전자의 드라이빙 제어 영역에 대한 정의와 해석이 다름을 보여준다. 본 연구는 외관으로 드러나지 않는 차량별 HMI의 특성을 실제 주행상황에서 파악해보았다는 점에서 기존의 연구와 차별적인 의미를 갖는다. 군집주행, 자율주행과 같은 주행환경의 변화와 HMI의 변화에서도 실제 주행을 통해 인터랙션의 차이를 확인해보는 본 연구의 접근이 유용하게 활용될 수 있기를 기대한다.

• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.672-678
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• 2006

A new approach to fabricate an enzyme electrode was described based on the immobilization of horseradish peroxidase (HRP) on dithiobis-N-succinimidyl propionate (DTSP) self-assembled monolayer (SAM) formed on gold-nanoparticles (Au-NPs) which were electrochemically deposited onto glassy carbon electrode (GCE) surface. The overall surface area and average size of Au-NPs could be controlled by varying deposition time and were examined by Field Emission-Scanning Electron Microscope (FE-SEM). The $O_2$ reduction capability of the surface demonstrated that Au-NPs were thermodynamically stable enough to stay on GCE surface. The immobilized HRP electrode based on Au-NPs/GCE presented faster, more stable and sensitive amperometric response in the reduction of hydrogen peroxide than a HRP immobilized on DTSP/gold plate electrode not containing Au-NPs. The effects of operating potential, mediator concentration, and pH of buffer electrolyte solution on the performance of the HRP biosensor were investigated. In the optimized experimental conditions, the HRP immobilized GCE incorporating smaller-sized Au-NPs showed higher electrocatalytic activity due to the high surface area to volume ratio of Au-NPs in the biosensor. The HRP electrode showed a linear response to $H_2O_2$ in the concentration range of 1.4 $\mu$M-3.1 mM. The apparent Michaelis-Menten constant ($K _M\; ^{app}$) determined for the immobilized HRP electrodes showed a trend to be decreased by decreasing size of Au-NPs electrodeposited onto GCE.