• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.34.2-35
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• 2018

Galaxy transition from star-forming to quiescent, accompanied with morphology transformation, is one of the key unresolved issues in extragalactic astronomy. Although several environmental mechanisms have been proposed, a deeper understanding of the impact of environment on galaxy transition still requires much exploration. My Ph.D. thesis focuses on which environmental mechanisms are primarily responsible for galaxy transition in different environments and looks at what happens during the transition phase using multi-wavelength photometric/spectroscopic data, from UV to mid-infrared (MIR), derived from several large surveys (GALEX, SDSS, and WISE) and our GMOS-North IFU observations. Our multi-wavelength approach provides new insights into the *late* stages of galaxy transition with a definition of the MIR green valley different from the optical green valley. I will present highlights from three areas in my thesis. First, through an in-depth study of environmental dependence of various properties of galaxies in a nearby supercluster A2199 (Lee et al. 2015), we found that the star formation of galaxies is quenched before the galaxies enter the MIR green valley, which is driven mainly by strangulation. Then, the morphological transformation from late- to early-type galaxies occurs in the MIR green valley. The main environmental mechanisms for the morphological transformation are galaxy-galaxy mergers and interactions that are likely to happen in high-density regions such as galaxy groups/clusters. After the transformation, early-type MIR green valley galaxies keep the memory of their last star formation for several Gyr until they move on to the next stage for completely quiescent galaxies. Second, compact groups (CGs) of galaxies are the most favorable environments for galaxy interactions. We studied MIR properties of galaxies in CGs and their environmental dependence (Lee et al. 2017), using a sample of 670 CGs identified using a friends-of-friends algorithms. We found that MIR [3.4]-[12] colors of CG galaxies are, on average, bluer than those of cluster galaxies. As CGs are located in denser regions, they tend to have larger early-type galaxy fractions and bluer MIR color galaxies. These trends can also be seen for neighboring galaxies around CGs. However, CG members always have larger early-type fractions and bluer MIR colors than their neighboring galaxies. These results suggest that galaxy evolution is faster in CGs than in other environments and that CGs are likely to be the best place for pre-processing. Third, post-starburst galaxies (PSBs) are an ideal laboratory to investigate the details of the transition phase. Their spectra reveal a phase of vigorous star formation activity, which is abruptly ended within the last 1 Gyr. Numerical simulations predict that the starburst, and thus the current A-type stellar population, should be localized within the galaxy's center (< kpc). Yet our GMOS IFU observations show otherwise; all five PSBs in our sample have Hdelta absorption line profiles that extend well beyond the central kpc. Most interestingly, we found a negative correlation between the Hdelta gradient slopes and the fractions of the stellar mass produced during the starburst, suggesting that stronger starbursts are more centrally-concentrated. I will discuss the results in relation with the origin of PSBs.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.9 no.1
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• pp.125-130
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• 2005

Background and purpose: We evaluated the reliability of two electrodermal measurement devices on meridian skin areas; Electro Acupuncture according to Dr. Voll (EAV) method and newly developed MIR-1. Methods: Eighteen volunteers were tested repeatedly on the same condition with each device. To explore the intra-rater, inter-rater, and test-retest reliabilities, one rater tested each subject twice in succession, then the other rater tested the subject in a row. Finally, retests on the subjects with each device were performed 1 week later. The reliability was determined by Pearson correlation and intraclass correlation statistics. Results: EAV method showed poor reliability, while MIR-1 showed good reliability. Conclusion: It is suggested that further research on the reliability and useful device in both fields of clinical practice and biomedical research.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.34.2-34.2
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• 2016

We study the mid-infrared (MIR) properties of galaxies in compact groups and their environmental dependence using the Wide-field Infrared Survey Explorer data. We use a sample of 670 compact groups and their 2175 member galaxies with $M_r$ < -19 and 0.01 < z < 0.0741 from Sohn et al. (2016), which were identified through a friends-of-friends algorithm. We find that the MIR [3.4]-[12] colors of early-type galaxies in compact groups are on average bluer than those of early-type galaxies in clusters. Furthermore, we find that when compact groups have both early- and late-type member galaxies, the MIR colors of the late-type galaxies in those compact groups can be bluer than those of late-type galaxies in clusters. We also find that as background galaxy number densities of compact groups increase, compact group galaxies have higher early-type galaxy fractions and bluer MIR colors. These trends are also seen for background galaxies. However, at a given background density, compact group galaxies always have higher early-type galaxy fractions and bluer MIR colors than the background galaxies. Our findings suggest that the properties of compact group galaxies depend on both internal and external environments of the compact groups, and that galaxy evolution is faster in compact groups than in clusters.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.1075-1080
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• 2009

이 글은 Music Information Retrieval(MIR) 기법을 사용하여 오디오 콘텐츠의 리듬 정보를 자동으로 분석하고 이를 시각화하는 방법에 대해 다룬다. 특히 MIR을 활용한 간단한 시각화(sound visualization) 어플리케이션을 소개함으로써 음악 정보 분석이 디자인, 시각 예술에서 다양하게 활용될 수 있음을 보이고자 한다. 음악적 정보를 시각 예술로 담아내려는 시도는 20세기 초 아방가르드 화가들에 의해 본격적으로 시작되었다. 80년대 이후에는 컴퓨터 기술의 급속한 발전으로 사운드와 이미지를 디지털 영역에서 쉽게 하나로 다룰 수 있게 되었고, 이에 따라 다양한 오디오 비주얼 예술작품들이 등장하였다. MIR은 오디오 콘텐츠로부터 음악적 정보를 분석하는 DSP(Digital Signal Processing) 기술로 최근 디지털 콘텐츠 시장의 확장과 더불어 연구가 활발히 진행되고 있다. 특히 웹이나 모바일에서는 이미 다양한 상용 어플리케이션이 적용되고 있는데 query-by-humming과 같은 음악 인식 어플리케이션이 대표적인 경우이다. 이 글에서는 onset 검출(onset detection)을 중심으로 음악적 리듬을 분석하는 알고리즘을 살펴보고 기본적인 조형원리에 따라 이를 시각화하는 어플리케이션의 예를 소개한다.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.37.1-37.1
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• 2012

We present mid-IR (MIR) and near-UV (NUV) properties of red sequence galaxies defined by optical color-magnitude relation. We use the Wide-field Infrared Survey Explorer (WISE) preliminary released data matched with the SDSS DR7/GALEX GR6. The red sequence galaxies with little emission lines show a wide spread of MIR (3.4um-12um) colors, implying a variety of MIR excess emission. We focus on the properties of the red sequence galaxies with MIR excess, comparing the properties of post-starburst galaxies to trace how galaxies migrate to the red sequence.

• Journal of Magnetics
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• v.6 no.1
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• pp.9-12
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• 2001

The dependence of the magnetoimpedance effect (MI) on magnetic properties has been investigated in mumetal thin films prepared by rf magnetron sputtering. Coercivity of thin films prepared at 400 W was about 0.4 Oe, and the magnetic anisotropy field of films deposited under a uniaxial magnetic field decreased with increasing film thickness. The saturation magnetization of mumetal films increased with rising input power and thickness and was smaller than that of permalloy films. Transverse incremental Permeability (TPR) of films of 1$\mu m$ thick increased with increasing effective permeability. The magneto impedance ratio (MIR) was proportional to TPR in films 1$\mu m$ thick but in spite of lower effective permeability at higher thicknesses, MIR increased due to skin effect. The height of the double peaks in the MIR curves decreased with decreasing anisotropy and thickness. The maximum MIR value for a 4$\mu m$ thick 75% at 36.5 MHz.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.12
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• pp.6207-6210
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• 2012

Introduction: Although a number of studies were published in the past several years on associations between hsa-mir-27a and cancer risk, the findings remain conflicting rather than conclusive. To derive a more precise effect on the association between SNP hsa-mir-27a rs895819 and breast cancer risk, we conducted a meta-analysis for the first time. Materials and Methods: Through retrieval from PubMed for the period up to August 2012, a total of four studies were identified with 3,287 cases and 4,298 controls for SNP hsa-mir-27a rs895819. We calculated summary odds ratio (ORs) and corresponding 95% confidence intervals (CIs) using a fixed effects model (when the heterogeneity was absent, P>0.10). Otherwise, the random-effects model was used. Results: We found that hsa-mir-27a rs895819 polymorphism also did not reveal any relationship with breast cancer susceptibility (AG versus AA: OR = 0.98; 95%CI, 0.73-1.32; GG versus AA: OR = 0.86; 95% CI, 0.72-1.03; AG/GG versus AA: OR = 0.92; 95% CI, 0.74-1.14), while significantly decreased risk was found among Europeans in AG versus AA and AG/GG versus AA models tested (AG versus AA: OR = 0.83; 95%CI, 0.72-0.97; GG versus AA: OR = 0.86; 95% CI, 0.71-1.05; AG/GG versus AA: OR = 0.84; 95% CI, 0.75-0.94). Conclusion: These findings suggest that hsa-mir-27a rs895819 polymorphism may play an important role in breast cancer development.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.1
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• pp.339-344
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• 2015

Epidemiologic findings concerning the association between the hsa-mir-499 rs3746444 A>G polymorphism and cancer risk have yielded mixed results. We aimed to investigate the association by performing a meta-analysis of all available studies. We searched PubMed and EMBASE for studies published up to November 2014, using odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of any association. The Benjamini-Hochberg (BH) method was used to correct the p values for multiple comparisons. We included 39 studies, including 14,136 cases and 16,937 controls. The results of overall meta-analysis suggested a borderline association between hsa-mir-499 rs3746444 polymorphism and cancer susceptibility (AG+GG vs. AA: OR=1.15, 95% CI=1.04-1.26, corrected p value=0.04). After removing studies not conforming to Hardy-Weinberg equilibrium (HWE), however, this association disappeared (AG+GG vs AA: OR=1.18, 95% CI=1.03-1.34, corrected p value=0.21). When stratified analysis by ethnicity, cancer type or HWE in controls, although some associations between hsa-mir-499 rs3746444 polymorphism and cancer susceptibility were detected, these associations no longer existed after adjustment using BH method. In conclusion, our meta-analysis suggests that hsa-mir-499 rs3746444 A>G polymorphism is not associated with risk of cancer based on current evidence.

• Journal of Life Science
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• v.29 no.7
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• pp.800-808
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• 2019

Charcot-Marie-Tooth disease (CMT) is a group of rare peripheral neuropathies characterized by progressive muscle weakness and atrophy and areflexia in the upper and lower extremities. The most common subtype of CMT is CMT1A, which is caused by a tandem duplication of the PMP22 gene in the 17p12 region. Patients with CMT1A show a loose genotype-phenotype correlation, which suggests the existence of secondary genetic or association factors. Recently, polymorphisms of rs71428439 (n.83A>G) and rs2292832 (n.86T>C) in the MIR149 have been reported to be associated with late onset and mild phenotypic CMT1A severity. The aim of this study was to examine the intrafamilial heterogeneities of clinical phenotypes according to the genotypes of these two SNPs in MIR149. For this study, we selected 6 large CMT1A families who showed a wide range of phenotypic variation. This study suggested that both SNPs were related to the onset age and severity in the dominant model. In particular, the AG+GG (n.83A>G) and TC+CC genotypes (n.86T>C) were associated to late onset and mild symptoms. Motor nerve conduction velocity (MNCV) was not related to the MIR149 genotypes. These results were consistent with the previous studies. Therefore, we suggest that the rs71428439 and rs2292832 variants in MIR149 may serve as genetic modifiers of CMT1A intrafamilial phenotypic heterogeneity, as they have a role in the unrelated patients. This is the first study to show an association using large families with variable clinical CMT1A phenotypes. The results will be helpful in the molecular diagnosis and treatment of patients with CMT1A.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.sup3
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• pp.219-224
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• 2016

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver making up more than 80 percent of cases. It is known to be the sixth most prevalent cancer and the third most frequent cause of cancer related death worldwide. Epigenetic regulation constitutes an important mechanism by which dietary components can selectively activate or inactivate target gene expression. The miR-34 family members including mir-34a, mir-34b and mir-34c are tumor suppressor micro RNAs, which are expressed in the majority of normal tissues. Several studies have indicated silencing of miR-34 expression via DNA methylation in multiple types of cancers. Bioactive nutrients like curcumin (Cur) have excellent anticarcinogenic activity and minimal toxic manifestations in biological systems. This compound has recently been determined to induce epigenetic changes. However, Cur is lipophilic and has a poor systemic bioavailability and poor absorption. Its bioavailability is increased through employing dendrosome nanoparticles. The aim of the current study was to investigate the effect of dendrosomal nanocurcumin (DNC) on expression of mir-34 family members in two HCC cell lines, HepG2 and Huh7. We performed the MTT assay to evaluate DNC and dendrosome effects on cell viability. The ability of DNC to alter expression of the mir-34 family and DNA methyltransferases (DNMT1, DNMT3A and 3B) was evaluated using semi-quantitative and quantitative PCR. We observed the entrance of DNC into HepG2 and Huh7 cells. Gene expression assays indicated that DNC treatment upregulated mir34a, mir34b and mir34c expression (P<0.05) as well as downregulated DNMT1, DNMT3A and DNMT3B expression (P<0.05) in both HepG2 and Huh7 cell lines. DNC also reduced viability of Huh7 and HepG2 cells through restoration of miR-34s expression. We showed that DNC could awaken the epigenetically silenced miR-34 family by downregulation of DNMTs. Our findings suggest that DNC has potential in epigenetic therapy of HCC.