• 한국전자파학회논문지
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• 제9권2호
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• pp.199-210
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• 1998

최근 들어 활발하게 연구되고 있는 저궤도 위성 이동 통신 시스템은 서비스 지역 내의 전파 수신 환경이 통신 품질을 좌우하므로, 시뮬레이션을 통해 수신 지역의 전파 환경을 분석.예측하는 것이 무엇보다도 중요하다. 본 논문에서는 파추적법을 이용하여 위성 서비스 지역내의 전파 수선 환경을 예측하였다. 먼저, 연구에 필요한 가상 공간 및 구조물을 설정한 뒤 위성의 방위각 및 앙각을 변화사켜 가면서 각 지점에서의 수신 전력 및 지연 프로파 일을 파추적법을 이용한 시뮬레이션을 통하여 구하였다. 본 논문의 목적은 2 GHz 주파수대역을 갖는 위성 통신 망에서의 전파 전달 특성을 해석하고 이해하는데에 있다. 이를 통해 위성 이동 통신에서의 송.수선 시스댐 설계와 위성망 구축에 도움을 줄 수 있을 것이다.

• Journal of Yeungnam Medical Science
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• 제41권2호
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• pp.134-138
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• 2024

Lung retransplantation (LRT) involves a second or subsequent lung transplant (LT) in a patient whose first transplanted graft has failed. LRT is the only treatment option for irreversible lung allograft failure caused by acute graft failure, chronic lung allograft dysfunction, or postoperative complications of bronchial anastomosis. Prehabilitation (rehabilitation before LT), while patients are on the waiting list, is recognized as an essential component of the therapeutic regimen and should be offered throughout the waiting period from the moment of listing until transplantation. LRT is particularly fraught with challenges, and prehabilitation to reduce frailty is one of the few opportunities to address modifiable risk factors (such as functional and motor impairments) in a patient population in which there is clearly room to improve outcomes. Although rehabilitative outcomes and quality of life in patients receiving or awaiting LT have gained increased interest, there is a paucity of data on rehabilitation in patients undergoing LRT. Frailty is one of the few modifiable risk factors of retransplantation that is potentially preventable. As such, it is imperative that professionals involved in the field of retransplantation conduct research specifically exploring rehabilitative techniques and outcomes of value for patients receiving LRT, because this area remains unexplored.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2321-2326
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• 2007

To return LNG to a gaseous state, it is fed into a regasification plant. For inland area, where pipelines do not exist or difficult to construct, the LNG is delivered to the inland-receiving terminal available at that area, regasified and delivered to consumers. At inland-receiving terminal, air-heating vaporizer type is usually used. To contribute in developing an efficient air-heating vaporizer, experiment on finned type air-heating vaporizer using 8 fins, 50 mm fin length (8fin50le) and 4 fins, 75 mm fin length (4fin75le) were conducted. The experiments were conducted by varying the ambient condition and the length of the vaporizer. The ambient air was controlled so that it has the same condition with air condition in every season available. $LN_2$ is used to substitute LNG because of safety reason. The results show that characteristics of the finned type 4fin75le vaporizer are comparable to finned type 8fin50le vaporizer at all season.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.375-385
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• 2016

Recently, several implantable hearing aids such as cochlear implant, middle ear implant, etc., which have a module receiving power and signal from outside the body, are frequently used to treat the hearing impaired patients. Most of implantable hearing aids are adopted permanent magnet pairs to couple between internal and external devices for the enhancement of power transmission. Generally, the internal device which containing the magnet in the center of receiving coil is implanted under the skin of human temporal bone. In case of MRI scanning of a patient with the implantable hearing aid, however, homogeneous magnetic fields of the MRI might be interfered by the implanted magnet. For the above reasons, the MR image is degraded by large area of artifact, so that diagnostics are almost impossible in deteriorated region. In this paper, we proposed an external coil system that can reduce the artifact of MR image due to the internal coupling magnet. By finite element analysis estimating area of MR artifact according to varying current and shape of the external coil, optimal coil parameters were extracted. Finally, the effectiveness of the proposed external coil system was verified by confirming the artifact at real MRI scan.

• 대한약침학회지
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• 제17권2호
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• pp.73-79
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• 2014

Objectives: This study was performed to analyze a 13-week repeated dose toxicity test of Sweet Bee Venom (SBV) extracted from bee venom and administered in Sprague-Dawley (SD) rats. Methods: Male and female 5-week-old SD rats were treated once daily with SBV (high-dosage group: 0.28 mg/kg; medium-dosage group: 0.14 mg/kg; or low-dosage group: 0.07 mg/kg) for 13 weeks. Normal saline was administered to the control group in a similar manner (0.2 mL/kg). We conducted clinical observations, body weight measurements, ophthalmic examinations, urinalyses, hematology and biochemistry tests, and histological observations using hematoxylin and eosin (H&E) staining to identify any abnormalities caused by the SBV treatment. Results: During this study, no mortality was observed in any of the experimental groups. Hyperemia and a movement disorder were observed around the area of in all groups that received SBV treatment, with a higher occurrence in rats treated with a higher dosage. Male rats receiving in the high-dosage group showed a significant decrease in weight during the treatment period. Compared to the control group, no significant changes in the ophthalmic parameters, the urine analyses, the complete blood cell count (CBC), and the biochemistry in the groups treated with SBV. Compared to the control group, some changes in organ weights were observed in the medium-and the high-dosage groups, but the low-dosage group showed no significant changes. Histological examination of thigh muscle indicated cell infiltration, inflammation, degeneration, and necrosis of muscle fiber, as well as fibrosis, in both the medium- and the high-dosage groups. Fatty liver change was observed in the periportal area of rats receiving medium and high dosages of SBV. No other organ abnormalities were observed. Conclusion: Our findings suggest that the No Observed Adverse Effect Level (NOAEL) of SBV is approximately 0.07 mg/kg in male and female SD rats.

• Journal of Nutrition and Health
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• 제45권2호
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• pp.181-191
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• 2012

The purpose of this study was to investigate parent's perception of a middle school foodservice in Masan city, Korea that uses environmentally friendly agricultural products (EFAP). From May 29, 2009 to July 11, 2009, questionnaires were distributed to 350 parents of middle schools located in Masan city. A total of 295 responded and 276 (response rate, 78.9%) were used for the final analysis after excluding improperly completed questionnaires. First, 47.8% of the parents responded that they had participated in the school foodservice operation (receiving food, attending foodservice-related events, working as a meal service aid, evaluating suppliers). Receiving food (53.7%) accounted for the greatest proportion in the participating area. Second, most subjects (83.0%) responded that they were aware of the use of EFAP. Additionally, 96.4% of the subject approved expanding the use of EFAP for all items. Third, their degree of interest in the school foodservice was 3.86, and satisfaction with the school foodservice was 3.94 based on a 5-point Likert scale. The overall satisfaction on the quality of EFAP used in the school foodservice was 3.68 based on a 5-point Likert scale. Fourth, awareness that the school used EFAP in the foodservice by the parents who participated in school foodservice operations was higher than that of parents who did not participate. Satisfaction (4.10) with the school foodservice by parents who participated in school foodservice operations was significantly higher than that (3.79) of parents who did not participate (p < 0.001). In conclusion, parent's participation in school foodservice operations should increase to improve the quality of the school foodservice and improve communication between parents and the school.

• 대한치과교정학회지
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• 제47권4호
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• pp.215-221
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• 2017

Objective: This questionnaire study aimed to estimate the overall frequencies of positive perception towards orthodontic treatment among adults categorized according to age, sex, and area of living, and to identify barriers or negative perceptions preventing them from receiving orthodontic treatment. Methods: The participants included 598 adults aged over 20 years (230 men and 368 women) who visited the Dental Hospital of Seoul St. Mary's Hospital. The participants' opinions regarding their consideration of receiving orthodontic treatment were recorded using a specially designed questionnaire. Results: The overall rate of positive perception towards orthodontic treatment was 48.5%. Compared to adults in their 20s (63.2%), those in their 40s and 50s had a lower percentage of interest in orthodontic treatment (46.2% and 45.1%, respectively; p < 0.05). Overall, women (52.2%) had a higher rate of interest than did men (42.6%; p < 0.05). The area of living had no effect on the percentage of interest. The order of priority of chief complaints differed according to age: protrusion for those in the 20s and 30s, and spacing for those in the 40s to 60s. Overall, the main reason for not seeking treatment was the treatment fee. Respondents aged over 40 considered themselves "too old" for orthodontic treatment. Conclusions: The middle-aged had a relatively high percentage of interest (above 45%) in orthodontic treatment. However, demographic characteristics were not significantly associated with the positive interest. These results highlight the need for educating the middle-aged about the limitations and possibilities of orthodontic treatment to increase its acceptance.

• 한국정보통신학회논문지
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• 제20권2호
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• pp.231-236
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• 2016

본 논문에서는 국내 DGPS 기준국 서비스 영역에서의 수신 전력의 안정도를 측정하고 변화율을 분석한다. 동절기와 하절기의 전력 측정과 주야간의 시간적 변화에 대한 DGPS 전파전파 영향을 측정 분석하여 안정된 DGPS 서비스 영역을 확보하기 위한 방안을 살펴본다. 내륙 DGPS 기준국과 해안 DGPS 기준국으로부터 일정 거리를 갖는 동일 지점에서 동절기와 하절기 그리고 낮과 밤의 전파 전파 특성을 일정시간별로 측정한다. DGPS 전파는 대지 도전율에 영향을 받으므로 대지 도전율의 시간적 변화율에 따라 수신되는 전파의 세기는 다르게 나타나며, 서비스 영역의 변화를 가져온다. 안정된 서비스 영역의 운영을 위해서는 적응형 전력 조절과 전리층의 영향을 고려한 안테나 설계가 필요할 수 있다.

• 한국물환경학회지
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• 제34권6호
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• pp.678-687
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• 2018

The purpose of this study was to understand the unique and complicated feature of urban stream receiving various inflows. The Yangjae stream, the second tier of the Han River, runs through the southern parts of Seoul, Korea and its middle part flows on the boundary of Seoul where land use is actively changing. Stream flow was greatly influenced by rainfall. Other than rainfall events, effluent discharge from wastewater treatment plant (WWTP) comprised 51 % of stream flux. As a result, majority ions water chemistry was changed at the receiving zone of the discharged effluent (Zone A). Its contribution increased to 69.9 % at the second sampling period with low stream flow. In the middle zone, inflows from the northern area, recently developed to a residential district showed low $NO_3-N$ and high $HCO_3$, Ca, $SO_4$, and $SiO_2$ indicating the effects of groundwater and concrete. One inflow (T-8), with extremely high Na and Cl, median $SiO_2$, was assessed to have anthropogenic influence, however its contribution to main stream was under 1 %. Road construction near Y-13 also affected water chemistry leading to the highest Na and Cl concentration. These hydro chemical changes can be critically used to evaluate the changes in water budget and fate of chemicals in a peri-urban watershed occasioned by human activities on the Yangjae.

• 한국산업정보학회논문지
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• 제19권4호
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• pp.1-8
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• 2014

음영 지역 해소 및 셀 커버리지 확대를 위하여 중계기를 활용하는 이동 통신 시스템이 널리 연구되고 있다. 본 논문에서는 중계기를 통해 다중 경로가 확보된 음영 지역에서 주파수 공간 블록 부호를 적용한 OFDMA(orthogonal frequency division multiple access) 전송 시스템을 제안한다. 다중 중계기에서 복원된 전송 신호에 대하여 주파수 공간 블록 부호를 적용하여 재전송함으로서 음영 지역 내 단말기의 수신 성능을 크게 향상시킬 수 있다. 실험을 통해, 제안된 주파수 공간 블록 부호화 OFDMA 전송 시스템의 성능이 기존의 단일 경로 OFDMA 전송 시스템의 성능보다 우수함을 확인한다.