• 한국정밀공학회지
• /
• 제20권11호
• /
• pp.117-126
• /
• 2003

GA(genetic algorithm) has a powerful searching ability and is comparatively easy to use and to apply as well. By that reason, GA is in the spotlight these days as an optimization skill for mechanical systems.$^1$However, GA has a low efficiency caused by a huge amount of repetitive computation and an inefficiency that GA meanders near the optimum. It also can be shown a phenomenon such as genetic drifting which converges to a wrong solution.$^{8}$ These defects are the reasons why GA is not widdy applied to real world problems. However, the low efficiency problem and the meandering problem of GA can be overcomed by introducing parallel computation$^{7}$ and gray code$^4$, respectively. Standard GA(SGA)$^{9}$ works fine on small to medium scale problems. However, SGA done not work well for large-scale problems. Large-scale problems with more than 500-bit of sere's have never been tested and published in papers. In the result of using the SGA, the powerful searching ability of SGA doesn't have no effect on optimizing the problem that has 96 design valuables and 1536 bits of gene's length. So it converges to a solution which is not considered as a global optimum. Therefore, this study proposes ExpGA(experience GA) which is a new genetic algorithm made by applying a new probability parameter called by the experience value. Furthermore, this study finds the solution throughout the whole field searching, with applying ExpGA which is a optimization technique for the structure having genetic drifting by the standard GA and not making a optimization close to the best fitted value. In addition to them, this study also makes a research about the possibility of GA as a optimization technique of large-scale design variable problems.

• 한국식품영양학회지
• /
• 제27권6호
• /
• pp.1078-1089
• /
• 2014

The purpose of this research was to reveal how Jong Ga and its cuisine is perceived by Koreans and foreign tourists and to develop Jong Ga culinary culture for culinary tourism. The Inje Jong Ga was chosen since it is located in Jeonju, Hanok Village, which is a destination for tourists and gourmet enthusiasts. In-depth personal interviews were performed with Koreans and with foreign tourists who were visiting Korea. Interviews were done to provide deeper insight into the comments and subject matters. Most tourists selected "having one table setting for each (Doksang)" as the most distinctive part of Jong Ga and its cuisine. To develop the experience at a Jong Ga as a culinary destination, questionnaires were created to study six areas: preferences on length of stay, price range, food serving style, things to be improved, expectations by as a tourist at a Jong Ga, and the role of the food guide. Perceptions toward Jong Ga and its cuisine were generally positive, but the quality of service and lack of organization in establishments were perceived to be the negative factors.

• 디지털콘텐츠학회 논문지
• /
• 제2권1호
• /
• pp.51-61
• /
• 2001

퍼지 제어기(FLC)는 고전적인 제어기 보다 외란에 강하고 초기치에 대한 과도응답도 우수할 뿐만 아니라 시스템의 수학적 모델과 파라메터 값을 알지 못하더라도 적절한 제어가 가능하다. 그러나 퍼지 제어기의 제어 규칙 생성은 전문가의 경험과 일단 결정된 제어 규칙은 고정됨으로 인해 제어 시스템의 환경변화에 적응할 수 없는 한계성이 있다. 또한 제어기의 출력값은 미세한 오차를 가지곤 있어 정확한 목표 값에 수렴할 수 없다. 이러한 미세한 오차를 없애기 위하여 여러 가지 방법이 연구되고 있는데, 본 논문에서는 FLC에 NN(Neural Network)과 GA(Genetic Algorithm)를 결합한 GA-FNNIC(유전알고리즘-퍼지 신경망 지능 제어기 : Genetic Algorithm - Fuzzy Neural network Intelligence Controller)를 제안한다. 제안된 GA-FNNIC와 FLC 제어기 간의 출력 특성, 수렴속도, 과도특성과 상승시간에 대해 비교 분석하고, 최종적으로 본 GA-FNNIC가 오차없이 목표치에 정확하게 수렴하는 것을 보인다.

• 제어로봇시스템학회논문지
• /
• 제12권4호
• /
• pp.328-338
• /
• 2006

A new evolutionary computation technique, called particle swarm optimization(PSO), has been proposed and introduced recently. PSO has been inspired by the social behavior of flocking organisms, such as swarms of birds and fish schools and PSO is an algorithm that follows a collaborative population-based search model. Each particle of swarm flies around in a multidimensional search space looking for the optimal solution. Then, Particles adjust their position according to their own and their neighboring-particles experience. In this paper, characteristics of PSO such as mentioned are reviewed and compared with GA which is based on the evolutionary mechanism in natural selection. Also dimensionalities of PSO and GA are compared throughout numeric experimental studies. The comparative studies demonstrate that PSO is characterized as simple in concept, easy to implement, and computationally efficient and can generate a high-quality solution and stable convergence characteristic than GA.

• 지역사회간호학회지
• /
• 제13권4호
• /
• pp.668-678
• /
• 2002

Purpose: The number of nursing home residents has been increasing in Korea. Nurses need to know the lived experience of relocation of the elderly to long-term care facilities. However, studies on this issue has not yet been conducted in Korea. Therefore, this study was carried out to understand the experience of institutionalization of the elderly using a phenomenological approach. Method: There were 11 participants who consisted of 5 men and 6 women living in 3 different nursing homes. The data was collected through in-depth interviews and participant observation from June 1999 to October 2001, and analyzed by Colaizzi's phenomenological method. Result: A total of 275 meaningful statements related to the experience of institutionalization by the elderly were obtained. Of the 275 statements, 175 were found as the statements with more general forms. 28 themes were grouped into 8 theme clusters. These theme clusters included' resentment at their sons', irresistible admission', 'humiliation on institutionalization', 'being unbearable to shock', 'grief to unfamiliarity', 'being in agony of outwards', 'regret for self-life' and 'comfort for new residence'. Conclusion: Based on these results. we can understand the lived experience of institutionalization of the Korean elderly. We need to develop a nursing program to help the elderly cope with this crisis, and studies about the familys experience on their parents admission to institutionalized facility warrant further exploration.

• 한국전자파학회논문지
• /
• 제15권3호
• /
• pp.258-264
• /
• 2004

본 논문에서는 40 ㎓ 대역 MMIC(Monolithic Microwave Intergrated Circuit) 이중평형 star 혼합기를 비아 공정이 있는 GaAs substrate(두께 4 mil)상에서 설계 및 제작, 측정하였다. 이중평형 star 혼합기를 구현하기 위해 발룬회로와 다이오드 설계가 필요했다. 발룬회로는 microstrip과 CPS(Coplanar Strip)를 이용하여 새로운 구조를 제안하여, 2 ㎓ 대역으로 주파수를 낮추어 새로운 구조의 발룬 성능을 PCB로 제작하여 확인한 바 있다. 이를 바탕으로 40 ㎓에서 MMIC 발룬을 설계하였다. 제안된 발룬은 비아 공정이 포함된 MMIC 회로에 적 합하며, 이중평형 혼합기 구현에 쉽게 적용 가능하다는 특징이 있다. 다이오드는 p-HEMT를 사용하는 밀리미터파 대역의 다른 MMIC 회로들과의 호환성을 고려하여, p-HEMT 공정을 기반으로 한 쇼트키 다이오드를 설계하였다. 이를 이용 제안한 발룬회로와 다이오드를 조합하여, 이중평형 star 혼합기를 구현하였다. 혼합기의 측정 결과 LO전력이 18 ㏈m일 때, 변환손실 약 30 ㏈를 얻었다. 이는 p-HEMT의 AlGaAs/InGaAs 층에 의한 다이오드 때문이며, p-HEMT구조에서 AlGaAs층을 식각하여 단일 접합 다이오드를 만들면 혼합기의 성능이 개선될 것으로 예상된다.

• 전기전자학회논문지
• /
• 제26권4호
• /
• pp.553-559
• /
• 2022

본 논문에서는 cascode GaN FET의 하프 브릿지 구성에서 오실레이션 억제를 위한 RC 스너버 회로 설계 기술을 분석한다. 대표적인 WBG 소자인 cascode GaN FET는 우수한 고속 스위칭 특성이 우수하다. 다만, 이러한 고속 스위칭 특성으로 인하여 false turn-off 문제가 야기되며, 이를 억제하기 위해 RC 스너버 회로가 필수적이다. 따라서, 일반적으로 많이 사용되는 실험 기반의 선정 기법과 근궤적법을 이용한 분석 기법을 비교한다. 일반적인 방법의 경우 실험적 경험을 바탕으로 오실레이션 억제 성능이 만족될 때까지 지속적인 회로 변경이 필요하다. 하지만, 근궤적 기법의 경우 비진동 R-C 맵을 기반으로 초기값을 설정 할 수 있다. 이러한 설계 기술에 따른 성능을 비교하기 위해 모의실험과 실제 더블 펄스 회로 구성을 통한 실험을 진행하였다.

• 한국재료학회지
• /
• 제12권6호
• /
• pp.431-435
• /
• 2002

The dark current and photocurrent(PC) spectrum of Mg-doped GaN thin film were investigated with various bias voltages and temperatures. At high temperature and small bias, the dark current is dominated by holes thermally activated from an acceptor level Al located at about 0.16 eV above the valence band maximum $(E_v)$, The PC peak originates from the electron transition from deep level A2 located at about 0.34 eV above the $E_v$ to the conduction band minimum $(E_ C)$. However, at a large bias voltage, holes thermally activated from A2 to Al experience the field-in-duces tunneling to form one-dimensional defect band at Al, which determines the dark current. The PC peak associated with the transition from Al to $E_ C$ is also observed at large bias voltages owing to the extended recombination lifetime of holes by the tunneling. In the near infrared region, a strong PC peak at 1.20 eV appears due to the hole transition from deep donor/acceptor level to the valence band.

• 한국치위생학회지
• /
• 제13권1호
• /
• pp.129-135
• /
• 2013

Objectives : The purpose of this study was to attempt to lay the foundation for the development of oral health programs geared toward promoting the oral health of low socioeconomic class children. Methods : The subjects of this study have been investigated for the use of children to 96 local children's center. Questionnaire for research purposes are described in more detail under the coordination of child care teachers to students, students to be able to record. The survey was conducted at the Health center. Analyzed the data collected by SPSS 18.0. Results : The findings of the study were as follows: The children were influenced by habits of having a snack in dental caries experience. Higher intake of bread and a lot of children more probability of dental caries experience. I've found a lot of sweet-food intake eleven cakes or fruits and vegetables that children prefer higher dental caries experience was low. Conclusions : Education on dietary behavior for low-income children was necessary because of the high correlation of the relationship between dietary habits and dental caries and diet.

• 대한장애인치과학회지
• /
• 제10권2호
• /
• pp.61-67
• /
• 2014

The aim of this study was to analyze the clinical characteristics of patients with cognitive and behavioral impairments receiving dental treatment under general anesthesia (GA-dental treatment). From August 2007 to April 2014, information was collected from 475 patients who received GA-dental treatment at the Clinic for Persons with Disabilities, Seoul National University Dental Hospital. The demographic factors (gender, age, disability, medication, GA history, residency type, caregiver, meal type, oral hygiene maintenance, and cooperation level) and dental status (operating duration, DMFT, malocclusion, periodontal disease, tooth defect, and treatment protocol) of the patients were evaluated. DMFT and malocclusion levels were compared among the patients with ANOVA and Sheffe's post-hoc test, and chi-square test, respectively. The correlation between the demographic characteristics and dental status of the patients were analyzed with the Pearson's correction test. The mean age of the patients was 27.1 (7 - 83) years and they had intellectual disabilities (55.4%), developmental disorders (17.9%), brain disorders (16.6%), neurocognitive disorders (4.6%), or others (5.5%). The mean DMFT (DT) was 8.6 (5.2) with a significant difference among the disability types (p<0.05). The incidence of malocclusion was higher in patients with intellectual disabilities and brain disorders than in the other types (p<0.05). The operation time ($191.4{\pm}91.2min$) was correlated with decayed or endodontically-treated teeth (p<0.05). Special needs patients requiring GA-dental treatment showed unfavorable oral conditions. Dental practitioners experience time restrictions and additional costs under a GA setting. Treatment planning and decision-making can be efficiently facilitated by evaluating the clinical characteristics of the patients.