• Steel and Composite Structures
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• 제38권1호
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• pp.17-31
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• 2021

Post-earthquake fire is a common disaster which causes serious safety issues to infrastructures. This study aims to investigate the residual loading capacities of circular concrete-filled steel tube (CFST) columns under post-earthquake fire experimentally and numerically. The experimental programme contains two loading steps - pre-damage cyclic loading at room temperature and transient state tests with constant compression loads. Three finite element models are developed and validated against the test results. Upon validation, a total of 48 numerical results were generated in the parametric study to investigate the effects of thickness and strengths of steel tube, axial compression ratio and damage degree on the fire resistance of circular CFST columns. Based on the analysis on experimental and numerical results, the loading mechanism of circular CFST columns is discussed. A design method is proposed for the prediction of fire resistance time under different seismic pre-damage and compression loads. The predictions by the new method is compared with the newly generated experimental and numerical results and is found to be accurate and consistent with the mean value close to the unity and a coefficient of variation around 1%.

• 한국건설관리학회논문집
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• 제18권5호
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• pp.59-67
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• 2017

공사 완료 시점에는 다양한 마감 공정들이 집중적으로 수행된다. 이는 현장관리자의 업무 부담을 가중시켜 경험에 근거한 임기응변적 품질관리 업무수행을 강제함으로써 감독자나 작업자의 개인역량에 따라 공사품질의 편차가 발생한다. 또한 품질관리와 관련된 정보가 시방서, 도면 등 다양한 유형의 문서에 산재하여 점검사항이 누락되는 경우가 빈번하다. 하자예방과 관련된 정보들을 체계적으로 저장하고, 상호참조 가능한 상태로 연계하여 실무자에게 점검업무 전 또는 수행 중에 효과적으로 제공할 수 있는 도구가 필요하다. 본 논문은 공동주택 마감공사의 품질점검 대상 액티비티 또는 실 단위로 필요한 정보를 체계적으로 저장 검색이 가능한 품질점검 지원 모델을 제안한다. 시방서, 설계기준, 체크리스트, 법규, 하자사례, 도면을 마감공사 프로세스 및 실과 연계하여 하자예방 정보베이스와 정보연계 넥서스를 구축하였으며 이를 바탕으로 정보등록 및 검색 인터페이스를 제시하였다. 내용적으로 다양한 하자예방 정보들을 마감공사 액티비티 및 실을 중심으로 연계하여 활용 가능한 틀을 제시함으로써 일정 수준 이상의 시공품질 확보에 기여할 수 있다.

• 대한간호학회지
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• 제25권2호
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• pp.316-329
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• 1995

The purpose of this study was to exame the effectiveness of the hand massage as an independent nursing intervention for the cancer patients undergoing radiation therapy. The data were collected with quasiexperimental research design from 40 subjects-20 for experimental group and 20 for control group-of the radiation oncology department of one university hospital in Seoul from January 10th to March 29th, 1994. Subjects agreed to participate in this study and ranged in age from 18 to 82 years with mean age of 52.63. They had insight of their disease and had undergone radiotherapy at least twice. The hand massage developed by Mariah Snyder (1993) based on the Swedish Massage was administered to the experimental group prior to having radiation therapy at the waiting place of radiotherapy room. Hand massage was given to each hand of patient for five minutes once a day. Measurement of the patient's blood pressure, pulse rate, state anxiety and mood were done before and after the administration of hand massage for 5 days. The data were analyzed with paired t-test, t-test an4 the results were summarized as follows ; 1. After administration of the hand massage, the diastolic blood pressure of experimental group was decreased significantly, while the systolic blood pressure and the pulse rate were decreased, but not significantaly. 2. In the experimental group, the level of anxiety was significantaly lower than control group. The mean scores of the difference of the anxiety level after having hand massage was 8.60 in the experimental group and 0.75 in the control group. 3. The difference of the mood scores before and after the massage in the experimental group was decreased significantly. The mean mood score was decreased 4.80 in the experimental group as compared with 2.02 in the control group. 4. The patients after having the hand massage expressed subjectively their feeling of relaxation, well - being and being enjoyable, the significant decreased of physical symptoms and anxiety. The findings summarized that the use of the hand massage for the cancer patient undergoing radiation therapy Produced significant changes in the level of anxiety and relaxation. Therefore it is recommended to use the hand massage as an intervention for the patients.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.139.1-139.1
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• 2016

Multiferroic materials are of great interest because of its potential applications in the design of devices combining magnetic, electronic and optical functionalities. Among various multiferroic materials, $BiFeO_3$(BFO) is known to be one of the intensively focused mainly due to the possibility of multiferroism at device working temperature (> $200^{\circ}C$). However, leakage current and weak polarization resulting from oxygen deficiency and crystalline defect should be resolved. Furthermore the magnetic ordering of pure BFO mainly prefers to have antiferromagnetic coupling. Up to now many attempts have been performed to improve the ferromagnetic and the ferroelectric properties of BFO by doping. In this work, we investigated the effects of Ni substitution on the multiferroism of bulk BFO. Four BFO samples (a pure BFO and three Ni-doped BFO's; $BiFe_{0.99}Ni_{0.01}O_3$, $BiFe_{0.98}Ni_{0.02}O_3$ and $BiFe_{0.97}Ni_{0.03}O_3$) were synthesized by the standard solid-state reaction and rapid sintering technique. The XRD results reveal that Ni atoms are substituted into Fe-sites and give rise to phase transition of cubic to rhombohedal. By using vibrating sample magnetometer and standard ferroelectric tester, the multiferroic properties at room temperature were characterized. We found that the magnetic moment of Ni-doped BFO turned out to be maximized for 3% of Ni dopant.

• 한국항공우주학회지
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• 제36권3호
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• pp.279-284
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• 2008

액체로켓추진시스템에서 추진제 가압시스템은 추진제가 저장되어 있는 탱크의 얼리지 공간에 가압제인 가스를 제어된 압력으로 공급하는 것이다. 이러한 추진제 가압시스템의 가장 중요한 설계변수는 극저온 추진제 탱크 내에 설치된 가압제 탱크에서 토출되는 가압제의 온도이며, 기체 상태인 가압제의 밀도는 토출되는 가압제의 온도에 따라 민감하게 변한다. 이전 연구에서는 상온 가압제와 상온 외부유체 간의 온도 상관성에 대한 연구가 수행되었으며, 본 연구에서는 현재 개발 중인 액체로켓추진 발사체의 가압시스템과 동일한 조건인 극저온 가압제(GHe)와 극저온 외부유체(LOX)를 적용하여 가압제 탱크에서 가압제 토출 시 강하되는 온도 변화를 실험 및 해석을 통하여 고찰하였다.

• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2309-2314
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• 2010

Design and syntheses of four red phosphorescent heteroleptic cationic iridium(III) complexes containing two substituted phenylquinoxaline (pqx) or benzo[b]thiophen-2-yl-pyridin (btp) main ligands and one 2,2'-biimidazole (H2biim) ancillary ligand are reported: [$(pqx)_2$Ir(biim)]Cl (1), [$(dmpqx)_2$Ir(biim)]Cl (2), [$(dfpqx)_2$Ir(biim)]Cl (3), [$(btp)_2$Ir(biim)]Cl (4). Complex 1 showed a distorted octahedral geometry around the iridium(III) metal ion with cis metallated carbons and trans nitrogen atoms. The absorption, emission and electrochemical properties were systematically evaluated. The complexes exhibited red phosphorescence in the spectral range of 580 to 620 nm with high quantum efficiencies of 0.58 - 0.78 in both solution and solid-state at room temperature depending on the cyclometalated main ligands. The cyclic voltammetry of the complexes (1-3) showed a metal-centered irreversible oxidation in the range of 1.40 to 1.90 V as well as two quasi reversible reduction waves from -1.15 to -1.45 V attributed to the sequential addition of two electrons to the more electron accepting heterocyclic portion of two distinctive cyclometalated main ligands, whereas complex 4 showed a reversible oxidation potential at 1.24 V and irreversible reduction waves at -1.80 V.

• Child Health Nursing Research
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• 제5권1호
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• pp.59-69
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• 1999

The main purpose of this study is to identify nursing needs of parents who have hospitalized child. Research design is a descriptive survey. The subjects for the study were 79 parents who have hospitalized child at a pediatric ward of one of the general hospital attached to a university in J city. The data was collected by researchers using a structured questionnaire. The questionnaire was Likert type 5 point scale, composed of 5 categories with 61 items. The data was analyzed by SPSS/PC. The results of the study were as follows ; 1) Mean score of nursing needs of subjects were 3.93 at 2nd day of admission and 3.99 at 7th day of admission. 2) Among the categories, the highest nursing need at the End day and 7th day of admission was ‘dilect nursing’, in desending order, ‘facilities and environment’, ‘education and counseling’, ‘nursing assessment’. The lowest nursing need was ‘reference’. 3) Differences between the nursing needs of subjects at 2nd day and 7th day were as follows : (1) By categories, there was a significant difference only in the ‘reference’ categoly(t=2.74, P=.008). (2) By items, there were significant differences in items of ‘to check necessary materials(t=2.31, P=.024)’, ‘to understand family function and family relationship(t=2.12, P=.041)’, ‘to set up study room(t=2.22, P=.030)’, and ‘to mediate parent's meeting group(t=3.89, P=.000)’. The above result indicated that nursing needs of parents with hospitalized child were above average, especially very high in items about disease process, and items directly associated with treatment and nursing care. So, nurses have to focus on information about the patient's state of disease, treatment, test and procedure, and in efficiently giving direct nursing care to implement mure effective care for the hospitalized children and their parents. And some future researche is needed to identify the difference of degree of nursing needs of parents with hospitalized child according to admission duration using a different sample and a longer sampling interval.

• 융합신호처리학회논문지
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• 제14권3호
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• pp.205-211
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• 2013

최근 공작기계 분야에서 가공속도와 가공정밀도 같은 시스템 성능이 한층 요구되고 있다. 특히 가공속도가 증가함에 따라 공작기계와 수가공 분야의 공작물 가공 부위에 유해한 열 발생을 초래하게 된다. 이 열은 가공 정밀도를 저하시키는 주된 원인으로 작용한다. 따라서 온도를 제어하는 오일쿨러는 공작기계에서 필수적이다. 일반적으로 두 가지 대표적인 제어기법인 핫가스 바이패스방식과 압축기 가변속 제어 방식이 오일쿨러에 채택 되었다. 본 논문에서는 공작기계에 사용하는 핫가스 바이패스 오일쿨러의 정밀한 온도특성을 얻기 위한 퍼지 제어기의 설계와 구현 방법을 다룬다. 출구 오일온도를 설정값과 실내온도로 잘 유지하도록 전자팽창밸브의 개도 각도를 제어하였다. 특히, 퍼지 제어기는 갑작스러운 외란에 의한 온도변화를 억제하는 기능을 포함하고 있다. 몇 가지 실험을 통하여 제안한 방법으로 목표 온도를 ${\pm}0.22^{\circ}C$정상상태 오차 이내로 제어할 수 있었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.58-64
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• 2007

액체로켓추진시스템에서 추진제 가압시스템은 추진제가 저장되어 있는 탱크의 얼리지 공간에 가압제인 가스를 제어된 압력으로 공급하는 것이다. 이러한 추진제 가압시스템의 가장 중요한 설계변수는 극저온 추진제 탱크 내에 설치된 가압제 탱크에서 토출되는 가압제의 온도이며, 기체 상태인 가압제의 밀도는 토출되는 가압제의 온도에 따라 민감하게 변한다. 이전 연구에서는 상온 가압제와 상온 외부유체 간의 온도 상관성에 대하여 수행되었으며, 본 연구에서는 현재 개발 중인 액체로켓추진 발사체의 가압시스템과 동일한 조건인 극저온 가압제(GHe)와 극저온 외부유체(LOX)를 적용하여 가압제 탱크에서 가압제 토출 시 강하되는 온도 변화를 실험 및 해석을 통하여 고찰하였다.

• 대한치과교정학회지
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• 제49권1호
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• pp.21-31
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• 2019

Objective: This study was performed to explore the effect of different bracket, archwire, and ligature combinations on resistance to sliding (RS) and rotational control in first-order angulation. Methods: Three types of brackets (multi-level low friction [MLF], self-ligating, and conventional brackets) coupled with four nickel-titanium archwires (0.012, 0.014, 0.016, and 0.018-inch diameter) and two stainless steel ligatures (0.20 and 0.25 mm) were tested in different first-order angulations ($0^{\circ}$, $2^{\circ}$, $4^{\circ}$, $6^{\circ}$, $8^{\circ}$, $10^{\circ}$, $15^{\circ}$, $20^{\circ}$) by using an Instron universal mechanical machine in the dry state at room temperature. RS value was evaluated and compared by one-way ANOVA. Results: Under the same angulation, the RS values showed the following order: conventional brackets > MLF brackets > self-ligating brackets. The RS was the highest for conventional brackets and showed a tendency to increase. The RS for MLF brackets coupled with thinner archwires and ligatures showed a similar tendency as the RS for the self-ligating bracket. In contrast, the RS for MLF brackets coupled with thicker archwires and ligatures increased like that for conventional brackets. MLF brackets showed the greatest range of critical contact angles in first-order angulation. Conclusions: The RS in first-order angulation is influenced by bracket design, archwire, and ligature dimension. In comparison with self-ligating and conventional brackets, MLF brackets could express low friction and rotational control with their greater range of critical contact angles.