• 한국지구과학회지
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• 제37권4호
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• pp.200-210
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• 2016

지음향 모델링은 퇴적층과 기반암의 해저 지층을 통해 전파되는 음파 특성을 예측하기 위해 사용된다. 이 연구는 동해 한국대륙주변부의 정동진 해역에서 50 m 퇴적층 심도의 4개 지음향 모델을 구성하였다. 지층 모델은 고해상 에어건 탄성파 자료, SBP 자료, 퇴적물 코어에 근거한다. P파 속도는 신호투과법에 의해 측정되었고, 압전기 트랜스듀서의 공진 중심 주파수는 1 MHz를 유지하였다. 42개 P파 속도와 41개 음감쇠 측정이 세 개 코어 퇴적물에서 수행되었다. 실제 모델링을 위해, 모델의 P파 속도는 Hamilton 방법을 이용하여 해저면 아래 현장 심도 속도로 보정하였다. 연안 지층의 이 지음향 모델은 동해 정동진 해역에서 지음향 특성의 수직/수평 변화를 반영하는 지음향/수중음향 실험을 위해 활용될 것이다.

• 한국조리학회지
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• 제8권3호
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• pp.91-106
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• 2002

To achieve these goals constituent dimensions and structural elements of the Japanese restaurants service quality are being investigated through the review of the food service industry and service. The survey about the importance and the Japanese restaurants was also conducted with a questionnaire to identify the tendency of customers who visited restaurants. These results and satisfactions hypotheses are being tested in the restaurant and the empirical research aye both conducted to achieve time research purposes. Japanese restaurants, located in the metropolitan area, are being selected as the object limits of the survey. Eighty-seven questionnaires are being distributed three kinds restaurants which means total 250 for all, and from which 230 are being analyzed. Frequency and $\chi$$^2$test were applied for the general matters and the conditions of object while Cronbach's Alpha coefficient and factor analysis were applied for reliability and validity. t-test was attempted to fine the importance and the satisfaction of the service quality. Also ANOVA was utilized. After examining the results of this survey, few facts were apparent. First the number of male ana female customers in the Japanese restaurants are divided evenly in about 55% of male customers and 45% of female customers. However, these people have a wide variety of jos. Another evident fact present on this survey shows that customers eating at a less expensive restaurants have a income of 1,000,000 won where as the expensive or high-end restaurants have customers with higher income than average. The price sensitive customers studied in this survey shows that they spend on average 30,000 to 70,000 won per person in the less expensive establishments. Therefore, with some service quality restructuring, application of new systems and ideas these restaurants could efficiently maximize their profit margin. Customers also showed that lower prices in lunch time would be an appealing incentive to deviate from standard lunch time 〈12:00~13:00〉and menu specials would be of interest to deviate from busy dinner time. In conclusion, since restaurants in the middle range category are not so many restaurants in lower range have a chance to maximize their profit. This study clearly shows that even the lower-end restaurants could raise their profit margin by incorporating new marketing techniques and by improving the service level of their restaurants.

• Journal of Chest Surgery
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• 제10권1호
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• pp.7-17
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• 1977

The increasing frequency of post-tracheostomy stenosis parallels the increase in the incidence of tracheostomy. The development of stenosis of trachea following the operation of tracheal tumor or tracheostomy is a very serious complication. The continuing need for an adequate tracheal substitute has not been answered, despite the necessities of excision and reconstruction of the trachea to keep for effective ventilation. Experimental tracheal reconstuction, with a prosthesis of heavy Marlex mesh and pericardium, _ vas performed in twelve dogs. Five to six tracheal ring circumferential defects were created and were bridged with heavy Marlex mesh fashioned into a tube of suitable diameter. Group A: A prepared cylinder of Marlex mesh was anastomosed outside the cut ends of the trachea. Group B: The external surface of the prepared cylinder of Marlex mesh was completely covered with suitably sized patch of pericardium and overlapped all margin of the Marlex mesh by 2 to 3 mm in each direction. Group C: The internal surface of the prepared cylinder of Marlex mesh was covered with suitably sized patch of pericardium and overlapped all margin of the Marlex mesh by 2 to 3 mm in each direction. The results of this exepriment were as follow: 1. In group A and B, the graft was well bridged with new granulation and fibrous tissue, and the lumen of trachea kept good patency for effective ventilation.. The interstices of Marlex became uniformly infiltrated with young well vasculated connective tissue. Epithelization has not yet occurred at 4 weeks in each group, but there were evidences of new growing mucosa at grafted site in 6 weeks. The remainder of the prosthesis was completely covered with glistening epithelium and the underlying fibrous tissue became more matured with little inflammation. These findings were more striking in group B than group A. 2. In group C, the covered pericardium was necrotized with stenosis of the lumen of grafted site due to poor blood supply.

• 전자공학회논문지
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• 제51권10호
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• pp.87-95
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• 2014

본 논문에서는 이중 채널 CIS(CMOS Image Sensor) 인터페이스를 위한 수신기 설계에 대해서 기술한다. 두 채널은 각각 CTLE(Continuous-Time Linear Equalizer)를 포함하며 샘플러, 병렬 변환기 그리고 clocking 회로로 구성되어 있다. Clocking 회로는 PLL, PI, CDR을 포함한다. CDR은 PI 기반이며 OSPD(Over Sampling Phase Detector)와 FSM(Finite State Machine)을 추가하여 빠른 락 소요 시간과 지연 시간, 향상된 jitter tolerance를 갖도록 하였다. CTLE는 3 GHz에서 -6 dB 손실을 갖는 채널의 ISI(Inter Symbol Interference)를 제거하며 CDR은 8000 ppm 이하의 주파수 오프셋에 대해 1 baud period 이내의 빠른 락 소요 시간을 갖는다. 65 nm CMOS 공정을 이용하여 설계하였으며 eye diagram에서 최소 368 mV의 전압 마진과 0.93 UI의 시간 마진을 갖는다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권14호
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• pp.5701-5707
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• 2014

Background: Salivary gland tumours, which account for approximately 3% of head-neck cancers, are a heterogeneous group and thus it is difficult to identify their epidemiological characteristics. The aim of this study is to determine demographic features and histopathologic distribution of parotid neoplasms in a large sample from Turkey. Materials and Methods: This study was conducted retrospectively on 136 parotidectomy materials from operations between May 2009-May 2013. Age, gender, tumor diameter, histopathological diagnosis and surgical margin status were recorded. Results: The benign cases were 112 (82.4%), while the malignancies were 24 (17.6%). The accuracy rate of FNAC was 91%. There were 46 (33.8%) male and 90 (66.2%) female patients. Female/male ratio (M/F=0.5) was two, the Warthin (WT) tumor being more apparent in males (p<0.05). Pleomorphic adenoma (PA) was detected most frequently among benign pathologies at 61.6% (69/112), while the Warthin Tumor (WT) was detected as the second most frequent tumor at 20.5% (23/112). Mucoepidermoid carcinoma (MEC) and carcinoma ex pleomorphic adenoma (Ca ex PA) were detected at equal frequency at 20.8% (5/24) among malign tumors. These were followed by acinic cell carcinoma at 16.7% (4/24). While the surgical margin was positive in ten patients with malignant tumors (41.7%), all of the benign tumors were negative (p<0.01). No significant difference was detected in the age-gender of patients, tumor size and distribution of sites among benign and malignant groups (p>0.05). Conclusions: Pleomorphic adenoma is the most frequently reported benign tumor almost in all global literature. Yet, the distribution of malignant tumors displays geographical differences. Based on these data, we believe that our findings will provide a significant contribution to future epidemiological studies. We think that it will be beneficial to generate awareness on parotid tumors and ensure a fight against smoking as with all head-neck cancers.

• 융합신호처리학회논문지
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• 제8권4호
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• pp.266-271
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• 2007

이동 채널 환경에서 신호는 다중경로 페이딩의 영향으로 통신품질이 크게 저하된다. 지금까지 이러한 페이딩의 영향은 기지국과 이를 중심으로 움직이는 이동 단말간의 이동 채널환경에서 고려되어왔다. 그러나 텔레매틱스 등과 같은 향후의 이동통신 서비스는 기지국과 같은 인프라를 통한 통신뿐만 아니라 단말기간 이동 ad-hoc통신도 활용될 것이므로 이런 통신환경에서의 페이딩 영향을 분석하고 다이버시티 기법에 대해 연구할 필요가 있다. 본 논문에서는 두 대의 차량을 이용하여 이동 통신 채널을 측정하고, 이 데이터를 활용하여 선형 빔형성 안테나의 페이딩 성능을 분석하였다. 채널 측정은 전 방향 안테나가 장착된 이동 차량에서 2GHz 대역의 QPSK 신호를 전송하고, 선형배열 안테나가 장착된 차량을 일정 지역을 이동하면서 수신 신호를 저장하였다. 빔 형성 안테나 기법의 페이딩 성능은 전방향 안테나에 대한 페이딩 마진의 향상 정도를 분석하였으며 선택 다이버서티를 사용한 경우와 비교하였다. 측정 데이터로부터 페이딩 깊이에 따른 CDF를 분석한 결과, 빔 형성 기술을 적용하면 선택 다이버서티를 적용한 경우에 비해 페이딩 마진이 페이딩 환경에 따라 6-7dB 향상됨을 알 수 있었다.

• 대한전자공학회논문지SD
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• 제37권8호
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• pp.1-8
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• 2000

0.3 g의 하드디스크 드라이브에 사용될 수 있는 마그네틱 헤드를 장착할 수 있는 트랙 추적용 마이크로 액추에이터를 제작하였다. 이 액추에이터는 정전방식을 적용하였으며 2${\mu}m$ 두께의 열산화막과 20${\mu}m$ 두께의 실리콘 막이 직접접합된 SOI 웨이퍼를 이용하여 단지 3장의 마스크만을 사용하여 제작하였다. 고유진동수는 18.5 kHz이고 15 V DC와 15 V AC 전압이 동시에 가해진 상황에서 그 변위가 1.4 ${\mu}m$이였고 이때 30 V일 때 50 N의 정전력을 나타내었다. 또한 2.21 kHz의 서보 주파수 대역에서 이득여유가 7.51 dB이고 위상여유가 50.98$^{\circ}$이였다. 따라서 이 트랙추적 마이크로 액추에이터는 10 Gb/in$^2$의 기록밀도를 요구하는 하드디스크 드라이브에 충분히 이용될 수 있을 것이다.

• Smart Structures and Systems
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• 제25권6호
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• pp.719-732
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• 2020

Real-time hybrid simulation (RTHS) which combines physical experiment with numerical simulation is an advanced method to investigate dynamic responses of structures subjected to earthquake excitation. The desired displacement computed from the numerical substructure is applied to the experimental substructure by a servo-hydraulic actuator in real time. However, the magnitude decay and phase delay resulted from the dynamics of the servo-hydraulic system affect the accuracy and stability of a RTHS. In this study, a robust stability analysis procedure for a general single-degree-of-freedom structure is proposed which considers the uncertainty of servo-hydraulic system dynamics. For discussion purposes, the experimental substructure is a portion of the entire structure in terms of a ratio of stiffness, mass, and damping, respectively. The dynamics of the servo-hydraulic system is represented by a multiplicative uncertainty model which is based on a nominal system and a weight function. The nominal system can be obtained by conducting system identification prior to the RTHS. A first-order weight function formulation is proposed which needs to cover the worst possible uncertainty envelope over the frequency range of interest. Then, the Nyquist plot of the perturbed system is adopted to determine the robust stability margin of the RTHS. In addition, three common delay compensation methods are applied to the RTHS loop to investigate the effect of delay compensation on the robust stability. Numerical simulation and experimental validation results indicate that the proposed procedure is able to obtain a robust stability margin in terms of mass, damping, and stiffness ratio which provides a simple and conservative approach to assess the stability of a RTHS before it is conducted.

• 한국식물병리학회지
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• 제10권1호
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• pp.54-60
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• 1994

Incidence of Rhizoctonia blight ranged from 22.2% to 100% in the golf courses at six geographical locations in Korea from 1989 to 1993. Rhizoctonia blight occurred more severly in southern area than in northern area. Fifty seven isolates of Rhizoctonia solani obtained from diseased parts of zoysiagrasses were grouped to AG2-2 by anastomosis test. Pathogenicity testes revealed that this pathogen was strongly pathogenic to Korean lawngrasses(Zoysia japonica, Z. matrella, Z. tenuifolia), but not pathogenic to creeping bentgrass(Agrostis palustris), bermuldagrass(Cynodon dactylon), Kentucky bluegrass(Poa pratensis), perennial ryegrass(Lolium prenne), and creeping red fescue(Festuca rubra subsp. rubra L.). The isolation frequency of R. solani AG2-2 fro sheaths of the infected plants was the highest by 91.67%, and that from stolons and roots was 11.13% and 5.63% respectively. The pathogen was not isolated from the leaves. Population density of R. solani in the lawn of large circular patch was highest on surface soils down to 1 cm deep with the value of 4.9$\times$104 (CFU/g soil), but below 1 cm population density decreased sharply down to 0.8~9.8$\times$103 (CFU/g soil). Horizontal distribution of propagules in turfgrass soil was higher in the margin than in center of patch, where the number of propagules was similar to these of healthy looking soils close to the margin of diseased patch. The meteorological factors influencing the outbreak of the disease were temperature, the number of rainy days and precipitation. Optimum temperature for disease development of Rhizoctonia blight in field was 20~22$^{\circ}C$, and that for hyphal growth of R. solani AG2-2 in vitro was 25~3$0^{\circ}C$. In Pusan area, Rhizoctonia blight first occurred in late April and rapidly developed in late June. The disease slightly decreased during July to August and developed again in late September in 1993. The monthly disease progress in Pusan area was similar to that in Kyeonggi province.

• 산업융합연구
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• 제16권2호
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• pp.33-39
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• 2018

본 논문은 선형 PID 제어기의 설계 방법에 대해서 설명하였고, 향후 설계 방법에 대해서 제안 하였다. 첫 번째 PID 설계 방법으로는 위상여유와 이득여유를 보장하는 방법이다. 이 방법은 주파수 영역에서 설계하는 것으로 안정도를 보장한다. 두 번째 방법은 내부 모델 제어 방법이다. 이 방법은 제어 모델에 대한 내부 모델을 동정 후 내부 모델의 파라미터를 이용하여 PID 제어기를 설계하는 것이다. 따라서 이 방법은 외란에 강한 특성을 갖고 있다. 마지막으로 제안하는 것은 Cascade-smith-Predictor 제어기 이다. 이방 법의 Cascade 제어기와 smith-Predictor의 구조를 결합한 것으로 강인제어와 최적제어 두 가지 장점을 갖는 제어기 구조이다. 이 방법은 최적 제어기 설계 방법으로 성능 평가지수를 얻을 수 있을 것이다. 이와 같은 PID 제어기 설계 방법은 비선형 방법의 기초가 되며, 지속적인 연구가 수행되고 있다.