• Elastomers and Composites
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• 제20권1호
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• pp.25-39
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• 1985

Elastomer-filler interaction in terms of characterization of filler effects was studied using natural rubber(NR) loaded with kaolin fillers modified with sodium polyphosphate and poly(maleic anhydride), respectively. Kaolins modified with sodium polyphosphate or poly(maleic anhydride) show adhering characteristics by Kraus plot. Reinforcement activity according to Cunneen-Russell method is given by those fillers, in which sodium polyphosphate-treated kaolin presents more favorable results than that treated with poly(maleic anhydride) with respect to adhesion constant, reinforcement extent, elastic constant, and crosslink density. When applied to Blanchard's linkage reinforcement theory, NR vulcanizates loaded with kaolin modified with sodium polyphosphate meet the requirements for both approximate linkage reinforcement(${\psi}'$) of 1.02 to 4.94 and accurate linkage reinforcement($\psi$) of 1.00 to 1.18, representing the values of effective wetting($C_{\psi}$) for 0.001 to 0.029 and intrinsic linkage reinforcement(${\psi}_0$) for 1.015 to 1.124, respectively, whille negligible linkage reinforcement is shown by NR vulcanizates loaded with kaolin treated with poly(maleic anhydride). Dynamic storage modulus(G') given by surface modified kaolins presents more favorable crosslink density rates of $2.260{\times}10^{-5}\;mole/cm^3-min$. for sodium polyphosphate treated kaolin and $1.305{\times}10^{-5}\;mole/cm^3-min$. for poly(maleic anhydride) treated kaolin, respectively, compared to untreated kaolin showing the rate of $1.033{\times}10^{-5}\;mole/cm^3-min$.

• 천문학회지
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• 제48권6호
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• pp.333-341
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• 2015

A search for hot and bright white dwarfs (WDs) in the Milky Way globular clusters M13 (NGC 6205) and M22 (NGC 6656) is carried out using the deep and homogeneous V I photometric catalog of Anderson et al. and and Sarajedini et al., based on data taken with the ACS/WFC aboard the Hubble Space Telescope (HST). V versus V − I color-magnitude diagrams (CMDs) of M13 and M22 are constructed and numerous spurious detections are rejected according to their photometric quality parameters qfit(V ) and qfit(I). In the case of M13, further radial restriction is applied to reject central stars with higher photometric errors due to central crowding. From each resultant V versus V −I CMD, sixteen and thirteen WD candidates are identified in M13 and M22, respectively. They are identified as stellar objects in the accompanying ACS/WFC images and are found to be randomly distributed across the central regions of M13 and M22. Their positions in the CMDs are in the bright part of the DA WD cooling sequences indicating that they are true WDs. In order to confirm their nature, follow-up spectroscopic observations are needed.

• 천문학회지
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• 제48권6호
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• pp.343-355
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• 2015

There is much observational evidence that active star formation is taking place in the Hii regions Sh 2-255 – 257. We present a photometric study of this star forming region (SFR) using imaging data obtained in passbands from the optical to the mid-infrared, in order to study the star formation process. A total of 218 members were identified using various selection criteria based on their observational properties. The SFR is reddened by at least E(B −V ) = 0.8 mag, and the reddening law toward the region is normal (R_V = 3.1). From the zero-age main sequence fitting method it is confirmed that the SFR is 2.1 ± 0.3 kpc from the Sun. The median age of the identified members is estimated to be about 1.3 Myr from a comparison of the Hertzsprung-Russell diagram (HRD) with stellar evolutionary models. The initial mass function (IMF) is derived from the HRD and the near-infrared (J, J −H) color-magnitude diagram. The slope of the IMF is about Γ = −1.6 ± 0.1, which is slightly steeper than that of the Salpeter/Kroupa IMF. It implies that low-mass star formation is dominant in the SFR. The sum of the masses of all the identified members provides the lower limit of the cluster mass (169M_⊙). We also analyzed the spectral energy distribution (SED) of pre-main sequence stars using the SED fitting tool of Robitaille et al., and confirm that there is a significant discrepancy between stellar mass and age obtained from two different methods based on the SED fitting tool and the HRD.

• 디지털콘텐츠학회 논문지
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• 제19권1호
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• pp.103-112
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• 2018

본 논문에서는 감정에 따라 변화하는 혈류량을 측정하는 PPG 센서를 사용하여 감정을 인식하는 방법을 제안한다. 기존의 PPG 신호로부터 전력스펙트럼밀도(PSD; Power Spectrum Density)를 통해 주파수 영역에서 긍정적인 감정과 부정적인 감정을 판단하는 방법을 활용한다. 제임스 러셀의 이차원 원형 모델에 기반을 두어 감정을 기쁨, 슬픔, 짜증, 평온으로 분류하여 주파수 영역에 따른 에너지의 크기와의 연관성을 살펴본다. 본 연구는 웨어러블 디바이스에서 사용되는 동일한 PPG 센서를 사용하여 상위 네 종류의 감정을 영상 실험을 통해 주파수 영역에서 측정하였다는 것에 의의가 있다. 설문 조사를 통해 정확도와 개인에 따른 몰입 정도와 감정 변화 및 영상에 대한 바이오피드백을 수집하였다. 제안하는 방법은 앞으로 PPG 센서를 사용하는 상용화된 웨어러블 디바이스와 기존에 사용하는 스마트폰의 상황정보와 융합되어 모바일 어플리케이션 예측 서비스 등 다양한 개발이 될 것으로 기대된다.

• 천문학논총
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• 제30권2호
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• pp.265-266
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• 2015

A search for luminous white dwarfs (WDs) in several nearby Galactic globular clusters (GCs) was carried out using the deep and homogeneous photometric catalog of Galactic GCs taken with the ACS/WFC aboard the Hubble Space Telescope (HST) by Sarajedini et al. and Anderson et al- It resulted in the identification of luminous WD candidates in the GCs M13 (NGC 6205) and M22 (NGC 6656). The purpose of the present study is to identify luminous WDs in the deep and homogeneous V versus V - I color-magnitude diagrams (CMDs) of several nearby Galactic GCs taken with the ACS/WFC aboard the HST. Using photometric data for the GCs M13 and M22 that are now in the public domain, the V versus V - I CMDs of the GCs M13 and M22 were constructed. Many spurious detections in the CMDs were removed using the photometric quality parameters qfit(V) and qfit(I), and a radial restriction was applied to the CMDs to remove the central stars with higher photometric errors due to central crowding. From each resultant V versus V - I CMD of the GCs M13 and M22, a dozen or so luminous WD candidates were identified. They were confirmed as stellar objects in the accompanying ACS/WFC images and their positions in the CMDs were in the bright part of the DA WD cooling curve. Therefore, the luminous WD candidates in the GCs M13 and M22 seem to be true luminous WDs, and spectroscopic observations are needed to confirm their true identity.

• 한국동물생명공학회지
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• 제37권4호
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• pp.285-291
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• 2022

In 1951, Colin Russell Austin and Min Chueh Chang identified "capacitation", a special process involving ejaculated spermatozoa in the female reproductive tract. Capacitation is a phenomenon that occurs in vivo, but almost all knowledge of capacitation has been obtained from in vitro studies. Therefore, numerous trials have been performed to establish in vitro capacitation methods for various studies on reproduction. Although a series of studies have been conducted to develop an optimal protocol for inducing capacitation, most have focused on identifying the appropriate chemical compounds to induce the capacitation of boar spermatozoa in vitro. Therefore, the purpose of this study was to identify the optimal incubation time for inducing capacitation in vitro. Duroc semen was incubated for various periods (60, 90, and 120 min) to induce capacitation. Sperm function (sperm motility, motion kinematic parameters, and capacitation status) was evaluated. The results showed that total sperm motility, rapid sperm motility, progressive sperm motility, curvilinear velocity, and average path velocity significantly decreased in a time-dependent manner. However, the capacitation status did not show any significant changes. Taken together, these results indicate that an incubation time of more than 60 min suppresses sperm motility and motion kinematic parameters. Therefore, we suggest that 60 min may be the best incubation time to induce capacitation without negative effects on sperm motility and motion kinematics in boar spermatozoa in vitro.

• 수완나부미
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• 제7권2호
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• pp.27-56
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• 2015

How should we conceptualize regions? What is the context in which new approaches to regional study take place? What is the role of historical change in the reconceptualization of regions or areas? This article addresses this issue by using two case studies to shed light on the history of regional study by comparing some of the ways in which the Middle East and Southeast Asia have been conceptualized. Accordingly, the discussion traces the ways in which these areas were understood in the 19th century by highlighting the ideas of a number of influential Victorian thinkers. The Victorians are useful because not only did British thinkers play critical roles in the shaping of modern patterns of knowledge, but their empire was global in scope, encompassing parts of both Southeast Asia and the Middle East. However, the Victorians regarded these places quite differently: Southeast Asia was frequently described as "Further India" and the Middle East was the home of the Ottoman Empire. Both of these places were at least partly understood in relation to the needs of British policy-makers, who tended to focus most of their efforts according to the needs of India-which was their most important colonial possession. The article exhibits the connections between the "Eastern Question" and end of the Ottoman Empire (and the political developments which followed) led to the creation of the concept of "Middle East". With respect to Southeast Asia, attention will be devoted to the works of Alfred Russell Wallace, Hugh Clifford, and others to see how "further India" was understood in the 19th century. In addition, it is clear that the successful deployment of the term "Southeast Asia" reflected the political needs of policy makers in wake of decolonization and the Cold War. Finally, by showing the constructive nature of regions, the article suggests one possible new path for students of Southeast Asia. If the characterization of the region is marked by arbitrary factors, it may actually point to a useful avenue of enquiry, a hermeneutic of expedience. Emphasis on the adaptive and integrative features of lived realities in Southeast Asia may well be a step beyond both the agendas of "colonial knowledge" and anti-colonial nationalism.

• 천문학회지
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• 제56권1호
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• pp.97-115
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• 2023

We present the deep homogeneous UBV RI photometric data of 135,071 stars down to V ~ 23 mag and I ~ 22 mag toward the Carina Nebula. These stars are cross-matched with those from the previous surveys in the X-ray, near-infrared, and mid-infrared wavelengths as well as the Gaia Early Data Release 3 (EDR3). This master catalog allows us to select reliable members and determine the fundamental parameters distance, size, stellar density of stellar clusters in this star-forming region. We revisit the reddening toward the nebula using the optical and the near-infrared colors of early-type stars. The foreground reddening [E(B-V)_fg] is determined to be 0.35 ± 0.02, and it seems to follow the standard reddening law. On the other hand, the total-to-selective extinction ratio of the intracluster medium (R_V,cl) decreases from the central region (Trumpler 14 and 16, R_V,cl ~ 4.5) to the northern region (Trumpler 15, R_V,cl ~ 3.4). It implies that the central region is more dusty than the northern region. We find that the distance modulus of the Carina Nebula to be 11.9 ± 0.3 mag (d = 2.4 ± 0.35 kpc) using a zero-age main-sequence fitting method, which is in good agreement with that derived from the Gaia EDR3 parallaxes. We also present the catalog of 3,331 pre-main-sequence (PMS) members and 14,974 PMS candidates down to V ~ 22 mag based on spectrophotometric properties of young stars at infrared, optical, and X-ray wavelengths. From the spatial distribution of PMS members and PMS candidates, we confirm that the member selection is very reliable down to faint stars. Our data will have a legacy value for follow-up studies with different scientific purposes.

• 한국간담췌외과학회지
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• 제27권1호
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• pp.76-86
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• 2023

Backgrounds/Aims: The aim of this study was to describe short- and long-term outcomes of patients who underwent pancreatoduodenectomy (PD) at a typical United Kingdom hepatopancreatobiliary unit. Methods: A retrospective analysis of all PD patients with histologically-confirmed pancreatic ductal adenocarcinoma (PDAC), ampullary adenocarcinoma (AA), or distal cholangiocarcinoma (CC) from September 1st, 2006 to May 31st, 2015 was carried out. The following information was obtained: demographics, comorbidities, preoperative investigations, neoadjuvant treatment, operative details, postoperative management, complications, adjuvant treatment, five-year recurrence, and five-year survival. Effects of selected preoperative variables on short- and long-term outcomes were investigated. Results: Of 271 included patients, 57.9% had PDAC, 25.8% had AA, and 16.2% had CC. In total, 67.9% experienced morbidity and 17.3% developed a Clavien-Dindo grade ≥ III complication. The 90-day mortality was 3.3%. Clinically-relevant postoperative pancreatic fistula, bile leak, gastrojejunal leak, postpancreatectomy haemorrhage and delayed gastric emptying affected 8.1%, 4.1%, 0.0%, 9.2%, and 19.9% of patients, respectively. American Society of Anesthesiologists grade III-VI correlated with overall morbidity (p = 0.002) and major morbidity (p = 0.009), but not 90-day mortality or five-year survival. The same pattern was observed in patients with a preoperative serum bilirubin > 29 µmol/L and/or a neutrophil/lymphocyte ratio > 3.1. Five-year cancer recurrence and five-year survival were 68.3% and 22.5%, respectively. PDAC patients had higher five-year recurrence but lower five-year survival rates (both p = 0.001). Conclusions: In our series, the majority of patients experienced a complication. However, few patients experienced major morbidity. Surgical risk factors did not affect five-year survival.

• 한국간담췌외과학회지
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• 제26권4호
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• pp.333-338
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• 2022

Backgrounds/Aims: Bile duct stones (BDS) can be managed either prior to laparoscopic cholecystectomy (LC) using endoscopic retrograde cholangiopancreatography (ERCP) or with laparoscopic bile duct exploration (LBDE) at the time of LC. The latter is underutilised. The aim of this study was to use the dataset of the previously performed CholeS study to investigate LBDE hospital volumes, LBDE-to-LC rates, and LBDE outcomes. Methods: Data from 166 United Kingdom/Republic of Ireland hospitals were used to study the utilisation of LBDE in LC patients. Results: Of 8,820 LCs performed, 932 patients (10.6%) underwent preoperative ERCP and 256 patients (2.9%) underwent LBDE. Of the 256 patients who underwent LBDE, 73 patients (28.5%) had undergone prior ERCP and 112 patients (43.8%) had undergone prior magnetic resonance cholangiopancreatography. Fifteen (9.0%) of the 166 included hospitals performed less than five LBDEs in the two-month study period. LBDEs were mainly performed by upper gastrointestinal surgeons (84.4%) and colorectal surgeons (10.0%). Eighty-seven percent of the LBDEs were performed by consultants and 13.0% were performed by trainees. The laparoscopic-to-open conversion rate was 12.5%. The median operation time was 111 minutes (range: 75-155 minutes). Median hospital stay was 6 days (range: 4-11 days) for emergency LBDEs and 1 day (range: 1-4 days) for elective LBDEs. Overall morbidity was 21.5%. Bile leak rate was 5.3%. Thirty-day readmission and mortality rates were 12.1% and 0.4%, respectively. Conclusions: The single-stage approach to managing BDS was underutilised. An additional prospective study with a longer study period is needed to verify this finding.