• 소음진동
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• 제9권3호
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• pp.600-606
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• 1999

본 논문은 길이 방향에 따라 단면적이 감소하는 경로와 증가하는 경로 2개가 존재할 경우 길이 방향에 따른 단면적 변화율과 경로의 길이에 의하여 특정 주파수에서 음파의 위상이 반대되는 현상이 발생하여 전달 경로 하단에서 해당 주파수의 소음이 상쇄되는 현상을 규명하였다. 단면적 변화를 고려한 1차 파동 방정식을 적용하여 매우 간단한 해석적인 해를 구하였으며, 원형 덕트 내의 속이 빈 콘 형상의 단면적 변화를 적용하여 실험적으로 검증하였다. 질량 효과에 의하여 필터링 주파수는 1, 2차 모드에서는 이론보다 더 낮은 주파수에서 결정되나, 3차 이상 고차 모드에서는 이론식으로 그 해당 주파수를 예측할 수 있다. 본 연구의 결과는 좁은 공간에서 덕트의 특정 소음의 주파수를 제거하여 음질을 개선할 필요가 있는 경우 이를 덕트 내부에 적용하는 콤팩트한 필터로 적용할 수 있다.

• 천문학회보
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• 제35권1호
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• pp.74.1-74.1
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• 2010

We have investigated the radial g-r color gradients of early-type galaxies in the Sloan Digital Sky Survey (SDSS) DR6 in the redshift range 0.00$H{\beta}$ absorption-line strengths and/or emission-line ratios that are indicative of the presence of young stellar populations. This implies that most of the residual star formation in early-type galaxies is centrally concentrated. Blue-cored galaxies are predominantly low-velocity dispersion systems. A simple model shows that the observed positive color gradients are visible only for a billion years after a star formation episode for the typical strength of recent star formation. The observed effective radius decreases and the mean surface brightness increases due to this centrally concentrated star formation episode. As a result, the majority of blue-cored galaxies may lie on different regions in the fundamental plane (FP) from red-cored ellipticals. However, the position of the blue-cored galaxies on the FP cannot be solely attributed to recent star formation but requires substantially lower velocity dispersion. We conclude that a low-level of residual star formation persists at the centers of most of low-mass early-type galaxies, whereas massive ones are mostly quiescent systems with metallicity-driven red cores.

• 천문학회보
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• 제35권2호
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• pp.33.1-33.1
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• 2010

We investigate the relation between the presence of bars in galaxies and AGN activities. Bars are believed to play an important role in fueling of AGN. Although there have been many previous studies on this topic, "the AGN-Bar Connection" is still an open question. To better understand the connection, we use a volume-limited sample of 9,726 late-type galaxies brighter than $M_r$=-19.5+5logh at $0.02{\leqq}z{\leqq}0.05489$, drawn from SDSS DR7. Among galaxies in the sample, 1,963 galaxies are classified as AGN-host galaxies based on the emission-line ratios while barred galaxies are identified by visual inspection. The bar fraction in AGN host galaxies (22.5%) is 3-times higher than in star-forming galaxies (8.6%). However, this trend is simply caused by the fact that the bar fraction increases with galaxy mass or luminosity and that AGN host galaxies are on average more massive than star-forming galaxies. Nevertheless, we find that among AGN host galaxies, the bar fraction increases with the Eddington ratio $(L_{[OIII]}/M_{[BH]})$, and this trend remains intact even at fixed galaxy luminosity and stellar velocity dispersion. These results imply that bars play a role in triggering AGNs.

• 천문학회보
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• 제42권1호
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• pp.45.1-45.1
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• 2017

Optical variability is one way to probe the nature of the central engine of AGN at smaller linear scales, and previous studies have shown that optical variability of AGN is more prevalent at longer timescales and at shorter wavelengths. To understand the properties and physical mechanism of variability, we are performing the KMTNet Active Nuclei Variability Survey (KANVaS). Especially, we investigated intra-night variability of AGN with KMTNet data which observed COSMOS field during 3 separate nights from 2015 to 2016 in B, V, R, and I bands. Each night was composed of 5, 9, and 11 epochs with 20-30 min cadence. To find AGN in the COSMOS field, we applied multi-wavelength selection methods. Using X-ray, mid-infrared, and radio selection methods, 50-60, 130-220, 20-40 number of AGN are detected, respectively. Achieving photometric uncertainty ~0.01mag by differential photometry, we employed a standard time-series analysis tool to identify variable AGN, chi-square test. Preliminary results indicate that there is no evidence of intra-night optical variability of AGN. It is possible that previous studies discovered intra-night variability used inappropriate photometric error. However, main reason seems that our targets have fainter magnitude (higher photometric error) than that of previous studies. To discover variability of AGN, we will investigate longer timescale variability of AGN.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제22권3호
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• pp.27-34
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• 2016

Purpose: The purpose of this paper is to develop a predictive model for patient visibility in Korean ICUs (corridor or continental type). Methods: The measures of static visibility were used to quantify the patient visibility (upper third part of the patient bed) from the nurse station. The measure of space programme and area distribution (patient zone percentage, staff zone percentage and departmental gross square meter per patient bed) were calculated by using AutoCAD and MS Excel programs. Regression analysis was conducted for visibility as dependant variable with independent variables of patient area percentage, staff area percentage as well as departmental gross square meter per bed by using IBM SPSS. Results: (1) Average patient visibility and percentage of patient area in ICU shows a strong negative correlation ($r^2$=0.66), p=0.01. (2) Patient visibility in Korean ICU (corridor or continental type) can be calculated as below with the given conditions: Y= $-1.449(X)+124.3{\pm}6$, Y is the total visibility of the ICU (corridor or continental type) and X is the percentage of patient area in the unit. Conditions:1. Given that the unit has a mixed programme of open bed and closed patient rooms and 2. The unit have a minimum of 20% patient rooms. Implications: This study may contribute to the visibility analysis of existing and future ICU design (corridor or continental type) in Korea to achieve maximum patient visibility and reduced patient mortality.

• Asian-Australasian Journal of Animal Sciences
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• 제33권10호
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• pp.1691-1698
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• 2020

Objective: The study sought to estimate the relationship between body surface temperature (BST) and temperature humidity index (THI) and to present the validity of THI as a heat stress index in the field. Methods: Eight Hanwoo heifers (20 to 32 month) were examined in a field trial, with a space allowance of 10 ㎡ per head. The BST was measured using an infrared thermographic camera. The BST of five body regions (eyes, hindquarters, nose, part of horns, and ears), ambient temperature (AT), and relative humidity (RH) were measured 7 times daily (07, 09, 11, 13, 15, 17, and 19 h) during each season with three replicates. Results: The THI ranged 34.0 to 56.9 during spring (AT, -1.0℃ to 13.4℃), 75.1 to 84.7 during summer (AT, 24.9℃ to 33.6℃), 55.8 to 70.9 during autumn (AT, 13.0℃ to 26.0℃) and 17.5 to 39.2 during winter (AT, -10.4℃ to 1.0℃). In the regression analysis, the coefficient of determination (R²) between THI and BST was 0.88, 0.72, 0.83, 0.86, and 0.85 for the eyes, hindquarters, nose, part of horn, and ears area, respectively. This indicates that BST has a strong correlation with AT and RH. Expression equations were estimated as Y (THI) = 31.54+0.1085X (BST of eyes) and Y (THI) = 30.48+0.1147X (BST of hindquarters) by simple linear regression analysis in this experiment. Conclusion: Consequently, the upper bound for heat stress estimation can be specified ranging from THI of 65 (eyes) to 70 (hindquarters). From this we can expect a precise feeding system for Korean native cattle in the field.

• 대한화학회지
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• 제22권2호
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• pp.86-94
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• 1978

Theophylline 鹽酸鹽의 結晶 및 分子 構造를 3次元的인 X-線 回折 data로부터 Patterson法에 의하여 決定하였고, Block-diagonal least square와 Fourier法으로서座標를 精密化하였다. 이化合物은 a = 14.01, b = 11.49, c = 6.77${\AA}$의 單位格子를 가지는 斜方晶系에 屬하는 結晶 이며 空間群은 $P_{na21}$ 이다. 743개의 觀測된 data에 대한 최종 R값은 12.2%이다. Theophylline 分子內 原子間 距離는 유사化合物에서 얻은 값과 거의 일치한다. 이들 原子는 同一平面을 이루고 있으며 HCl의 鹽素原子는 theophylline의 N(1) 原子와 3.06${\AA}$ 距離의 Cl${\cdot}{\cdot}{\cdot}$N(1), 水素結合을 이루고 있다. 모든 分子 는 대략 (001)과 (002)面上에 배열되어 있고 各分子間은 van derWaals force에 의해 三次元的 構造를 이루고 있다.

• 한국소음진동공학회논문집
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• 제22권11호
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• pp.1113-1120
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• 2012

This paper deals with the analysis of interior noise and low frequency noise characteristic for the Busan citizens to use public transport, Busan Metro Line 3. The interior noise evaluation index, articulation index(AI) is evaluated the lower value about average 22 % in a whole range, this is difficult to have a conversation. Also, noise criteria(NC) curve is partially evaluated as NC-65 below 2000 Hz, space type is evaluated as factories. Another of interior noise evaluation index, preferred speech interference level(PSIL) is evaluated the upper value about average 66 dB(A) in a whole range, this is evaluated to be interrupted. In the case of low frequency noise(20~200 Hz), the measurement of low frequency noise is assessed largely beyond noise criteria of ISO 226. The low frequency noise should be reduced because low frequency noise affects on psychological stress and displeasure although low frequency noise is not recognized by auditory sense. The low frequency noise criteria and guideline will be enacted from now on in Korea.

• The Korean Journal of Pain
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• 제12권1호
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• pp.95-100
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• 1999

Background: About 75% of terminal cancer patients have severe pain. For the treatment of these patients, physicians usually use potent opioid analgesics. But many of the cancer patients were not controlled by IV or IM injection of opioids. In spite of the untreatable nature of the patient's illness, they should be hospitalized only for pain control. In that case, epidural opioid injection is one of the most effective methods in pain management. Methods: We retrospectively analyzed 126 terminal cancer patients who were treated with epidural morphine for pain management from 1993-97. In the routine procedure, an epidural catheter was inserted into the epidural space and tunnelled subcutaneously, exiting out from the anterior chest or abdomen. Morphine was used as the main analgesic and Multiday Infusor$^{(R)}$ (Baxter, 0.5 ml/h) as a continuous infusion system. Results: 1. Mean treatment time was 55 days (range; 3~373). 2. Mean daily epidural start mg dose of morphine was 8 mg (range; 2~20). 3. Mean daily dose at termination was 19 mg (range; 4~60) 4. 94 patients were controlled with continuous infusion but 32 patients needed additional bolus doses of morphine. 5. heter-associated subcutaneous infection occurred in 2 patients (1.6%). Conclusion: Terminal cancer pain management administered by a tunnelled epidural catheter is a simple, inexpensive method with a very small rate of infection.

• 천문학회지
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• 제37권4호
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• pp.143-149
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• 2004

We present photometric results for four new variable stars discovered in the vicinity of the ZZ Ceti-type pulsating white dwarf BR Cam. Observations were performed on 5 nights in November 2003 using the 1.8m telescope at Bohyunsan Optical Astronomy Observatory with no filter, on 3 nights in December 2003 using the 0.61m telescope at Sobaeksan Optical Astronomy Observatory with V, I filters, and on 3 nights in October 2004 using the 1.0m telescope at Mt. Lemmon Optical Astronomy Observatory with V, I filters. We estimated their periods from the phase-match technique for one eclipsing binary and the multiple frequency analysis for three pulsating stars. By considering the light curve shape, period and amplitude difference between two passbands, we classified the objects by their variability types as follows: V1 (USNO-A2.0 1425-05691757) is a W UMa-type eclipsing binary with an orbital period of $0^d.4641$; V2 (USNO-A2.0 1425-05703335) is a multi-periodic $\delta$ Set-type pulsating star with a dominant period of $0^d.0649$; V3 (USNO-A2.0 1425-05699659) is also a $\delta$ Set-type pulsating star with a period of $0^d.1408$; and V 4 (USNO-A2.0 1425-05707705) is a RR Lyr-type pulsating star with a period of $0^d.2643$.