• Journal of Chest Surgery
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• v.34 no.10
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• pp.763-768
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• 2001

Background: The high pressure zone(HPZ) at the gastroesophageal junction is an important barrier for prevention of gastroesophageal reflux. Smooth muscle layers in the lower esophageal sphincter mainly contributes to HPZ at the throacoabdominal junction. The purpose of this study was to investigate the manometric characteristics of the thora-coabdominal junction in patients after surgical removal of the lower esophageal sphincter. Material and Method: Twenty two patients with prior esophagogastrectomy(10 Ivor-Lewis method and 12 left thoracotomy) and 30 normal adults(control group) were studied manometrically. Result: Esophageal manometry showed a HPZ and pressure inversion points distal to the anastomosis in 12 of 22 patients(2 of 10 patients with Ivor-Lewis method and 10 of 12 patients with left thoracotomy) and a HPZ in 30 of 30 normal adults. The location of HPZ front nostril was not significant different between the two groups(42.5$\pm$0.9cm in patients and 43.9$\pm$2.1cm in the control), while the length of HPZ was shorter in patients than in the control(2.13$\pm$0.6cm vs 2.83$\pm$0.59cm). By SPT and RPT, pressures of HPZ at rest were lower in patients(13.78$\pm$1.63mmHg, 28.58$\pm$6.06mmHg) than in control(20.3$\pm$4.95mmHg, 42.80$\pm$15.91mmHg). The HPZ relaxed partially in response to deglutition(84.4% in patient, 90.5% in control group) and contracted in response to increased intra- abdominal pressure induced by leg lifts(HPZ/ Intra-abdominal pressure= 1.81$\pm$0.23 in patient, 2.13$\pm$ 0.58 in control group).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.281-286
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• 1993

Projection TV에는 시각 품질을 최종적으로 표시하는 디스플레이 소자인 비구면플라스틱 렌즈를 적용하고 있으나 전량 일본에서 완제품으로 공급 받고 있다. 플라스틱 비구면 렌즈를 성형하기 위해서는 사출 공정에 대한 철저한 이해 와 폴리머의 광탄성 거동에 대한 개념이 핵심이라고 말할 수 있다. 복굴절성 실험은 폴리머의 유변학적 거동을 파악 하는데있어 가장 유용한 실험중의 하나이다. 본 글에서는 이와 관련된 사항인 복굴절성, 잔류 응력 형성 메카니즘, 밀도이완 작용의 상관관계와 비구면 렌즈의 성형 조건 및 공정에대해 기술 하였고, 또한 측정된 수지데이타를 이용 상용 S/W를 사용하여 유동, 냉각, 보압 ( 압축) 및 수축 해석을 실시 하여 각 stage에서 경험한 온도 와 압력의 이력에따라 변화하는 열 응력에 기인한 잔류 응력 계산 Pg을 개발 상용 S/W 와 비교 검증 하였다.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.415-419
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• 1997

The left ventricular relaxation rate is used as a golden standard which describes the left ventricular diastolic unction. So far, to get the rate of relaxation one should calculate the data after full recording, that is, off-line method. Therefore one cannot get the rate of relaxation in real-time while changing loading condition or infusing drug. But real time monitoring of the relaxation rate is necessary while changing loading condition or infusing drug to control the mechanics of heart and to get more information. We propose a new criterion to get the left ventricular relaxation rate and a real time algorithm. By comparison, it was turned out that our criterion outperforms others criterion.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.63-66
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• 2009

본 연구의 목표는 사용자에게 적합한 매트리스를 선택하는데 도움을 주는 신체적, 심리적 지표를 개발하고, 이를 분석하여 개인의 주관적 만족도와의 상관성을 알아보는 것이다. 시중에 판매되고 있는 5개의 매트리스의 강도를 2개씩 짝지어진 매트리스별 pared t-test를 통하여 강도별 순위를 5등급으로 분류하였다. 10명의 실험 참가자들의 신체적 지표(근전도, 심박수, 산소포화도 측정), 심리적 지표(개인 특성 설문 조사), 체압 및 주관적 만족도 측정을 실시하고, 상관분석을 통해서 이 측정결과와 개인간 주관적 만족도(선호하는 침대의 탄성)와도 일관성이 있는지 조사하였다. 연구 결과, 압력집중도(r=0.818)과 허리근육이완도(r=0.766) 그리고 심박수(r=0.670)가 주관적 만족도와 유의한 상관관계를 가지는 것으로 나타났다.

• Korean Journal of Materials Research
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• v.5 no.5
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• pp.512-517
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• 1995

EMI 대책용 전자파 흡수체로 알려진 cu-Ni-쿠 페라이트를 분말야금법으로 제조하여, 성형압력과 소결온도의 변화에 따른 미세조직을 과낯ㄹ하고, 투과반사법으로 전자파 흡수능을 측정하여 조직과의 관계로 검토하였다. 하소는 공기중에서 90$0^{\circ}C$로 2시간동안 행하는 것이 최적이었다. 미세조직과 입자의 크기는 성형압과 소결온도로 제어할 수 있다. 100Mpa로 성형한 것이 치밀하고, 전자파 흡수특성이 우수하였다. 복소유전율과 복소투자율은 기공도와 소결밀도에 영향을 받았다. 전자파흡수능은 밀도보다는 입자의 크기에 더 큰 영향을 받았다.

• Annual Conference of KIPS
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• 2021.05a
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• pp.551-552
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• 2021

본 논문에서는 촬영한 피부 영상(얼굴, 손 등)을 이용한 생체신호(맥박, 호흡, 혈압, 체온 등) 측정 S/W 기술을 제안한다. 기존의 생체신호 측정 기술은 다양한 센서(PPG, 압력 센서, 혈압계, 체온계 등)가 탑재된 측정 장치를 이용하여 상태를 측정하고 이를 진단하는 연구들이 진행되어 왔다. 각 각의 생체신호를 측정하기 위해서는 별도로 구비된 측정 장치들을 이용하여 개별적으로 생체신호를 측정하고 확인하여야 한다. 제안된 기술은 스마트 디바이스에 생체신호 측정 S/W의 설치만으로 카메라로 촬영한 피부 영상의 피부 관심 영역에서 계산된 색상 데이터를 이용하여 다양한 생체신호를 언제 어디서나 실시간으로 측정할 수 있으며, 생체신호 측정 성능 평가 결과 맥박수 2.63%, 호흡수 5.98%, 이완기 혈압 2.48%, 수축기 혈압 5.23% 및 체온 0.25%의 오차율이 계산되었다.

• Journal of Convergence for Information Technology
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• v.9 no.11
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• pp.227-233
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• 2019

The purpose of this study is to evaluate the quality of chest compression by conducting comparison research between mechanical chest compressor(LUCAS) and manuale cardiopulmonary resuscitation(CPR) in a out-of-hospital environment and suggest effective advanced cardiac life support using mechanical chest compressors. For this, a out-of-hospital cardiac arrest was simulated with a team of 3 ambulance workers, and manuale CPR and CPR using LUCAS were performed on site and during transport in an ambulance. The research results are as follows: the comparison of manuale CPR between on site and in an ambulance revealed that on-site manuale CPR showed significant differences in the average compression depth, compression rate, and relaxation rate. Second, the comparison between manuale CPR and LUCAS in an ambulance showed significant differences in the average compression depth, compression rate, the number of compression per minute.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.6
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• pp.653-664
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• 2015

When the structural analysis is performed for the concrete lining of the water pressure tunnel, many parameters are considered such as relaxed ground loads, internal water pressure, external water pressure, the shrinkage of the concrete lining, grouting pressure, etc. But, there are no standards and manuals for the structural analysis for the concrete lining of the water pressure tunnel. Above all, the external water pressure has an much effect on the stability of tunnel. So, in case that permeability of ground is large, the external water pressure should be decreased by installation of weep hole, or reinforced ground by ground improvement grouting should be pressed by the external water pressure instead. But, when weep hole is installed to reduce the external water pressure, the many problems may me occurred. Thus, reasonable approach for treatment of the external water pressure is necessary if weep hole is not installed. Therefore, the purpose of this study is to analyze design cases and studies for treatment of the external water pressure in performing structural analysis for the concrete lining of the water pressure tunnel, and to find reasonable method for tunnel lining modeling which is the treatment of the external water pressure according to permeability of ground and consequently the design of ground improvement grouting.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.24-33
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• 2002

Objectives: Nasal continuous positive airway pressure (CPAP) corrected elevated blood pressure (BP) in some studies of obstructive sleep apnea syndrome (OSAS) but not in others. Such inconsistent results in previous studies might be due to differences in factors influencing the effects of CPAP on BP. The factors referred to include BP monitoring techniques, the characteristics of subjects, and method of CPAP application. Therefore, we evaluated the effects of one night CPAP application on BP and heart rate (HR) reactivity using non-invasive beat-to-beat BP measurement in normotensive and hypertensive subjects with OSAS. Methods: Finger arterial BP and oxygen saturation monitoring with nocturnal polysomnography were performed on 10 OSAS patients (mean age $52.2{\pm}12.4\;years$; 9 males, 1 female; respiratory disturbance index (RDI)>5) for one baseline night and another CPAP night. Beat-to-beat measurement of BP and HR was done with finger arterial BP monitor ($Finapres^{(R)}$) and mean arterial oxygen saturation ($SaO_2$) was also measured at 2-second intervals for both nights. We compared the mean values of cardiovascular and respiratory variables between baseline and CPAP nights using Wilcoxon signed ranks test. Delta ($\Delta$) BP, defined as the subtracted value of CPAP night BP from baseline night BP, was correlated with age, body mass index (BMI), baseline night values of BP, BP variability, HR, HR variability, mean $SaO_2$ and respiratory disturbance index (RDI), and CPAP night values of TWT% (total wake time%) and CPAP pressure, using Spearman's correlation. Results: 1) Although increase of mean $SaO_2$ (p<.01) and decrease of RDI (p<.01) were observed on the CPAP night, there were no significant differences in other variables between two nights. 2) However, delta BP tended to increase or decease depending on BP values of the baseline night and age. Delta systolic BP and baseline systolic BP showed a significant positive correlation (p<.01), but delta diastolic BP and baseline diastolic BP did not show a significant correlation except for a positive correlation in wake stage (p<.01). Delta diastolic BP and age showed a significant negative correlation (p<.05) during all stages except for REM stage, but delta systolic BP and age did not. 3) Delta systolic and diastolic BPs did not significantly correlate with other factors, such as BMI, baseline night values of BP variability, HR, HR variability, mean SaO2 and RDI, and CPAP night values of TWT% and CPAP pressure, except for a positive correlation of delta diastolic pressure and TWT% of CPAP night (p<.01). Conclusions: We observed that systolic BP and diastolic BP tended to decrease, increase or remain still in accordance with the systolic BP level of baseline night and aging. We suggest that BP reactivity by CPAP be dealt with as a complex phenomenon rather than a simple undifferentiated BP decrease.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.231-240
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• 2017

Recently, there have been frequent occurrences of ground sink in the urban area, which have resulted in human and material damage and are accompanied by economic losses. This is caused by artificial factors such as soil loss, poor compaction, horizontal excavation due to the breakage of the aged sewage pipe, and lack of water proof at vertical excavation. The ground sink can be prevented by preliminary restoration and reinforcement through exploration, but it can be considered that it is not suitable for urgent restoration by the existing method. In this study, a model experiment was carried out to simulate the in-ground cavities caused by groundwater flow for developing non-excavation urgent restoration in underground cavity and the range of the relaxation zone was estimated by detecting the around the cavity using a relaxation zone detector. In addition, disturbance region and relaxation region were separated by injecting gypsum into cavity formed in simulated ground. The shape of the underground cavity due to the groundwater flow was similar to that of the failure mode III formed in the dense relative density ground due to water pipe breakage in the previous study. It was confirmed that the relaxed region detected using the relaxation zone detector is formed in an arch shape in the cavity top. The length ratio of the relaxation region to the disturbance region in the upper part of the cavity center is 2: 1, and it can be distinguished by the difference in the decrease of the shear resistance against the external force. In other words, it was confirmed that the secondary damage should not occur in consideration of the expandability of the material used as the injecting material in the pre-repair and reinforcement, and various ground deformation states will be additionally performed through additional experiments.