Simultaneously Achieving a Large Negative Dispersion and a High Birefringence Over Er and Tm Dual Gain Bands in a Square Lattice Photonic Crystal Fiber

Lee, Yong Soo,Lee, Chung Ghiu,Bahloul, Faouzi,Kim, Soeun,Oh, Kyunghwan IEEE 2019 Journal of Lightwave Technology Vol.37 No.4

<P>We proposed a novel photonic crystal fiber composed of a double-cladding square lattice that could be used in dual-band, Er and Tm optical gain bands, simultaneously supporting a large negative dispersion and a high birefringence. We theoretically investigated the light guiding property through the proposed photonic crystal fiber by using a vectorial finite-element method with a perfectly matched layer. By optimizing the structural parameters, we obtained an ultra-large negative dispersion of −20,186 ps/(nm·km) and a very high birefringence of 9.27 × 10<SUP>−3</SUP> at the wavelength of 1.55 <I>μ</I>m in the Er gain band and a very large negative dispersion of −8,067 ps/(nm·km) and a high birefringence of 1.0 × 10<SUP>−3</SUP> at the wavelength of 1.87 <I>μ</I>m in the Tm band. We further discussed the roles of waveguide parameters on the chromatic dispersion, its slope, and the birefringence of the fiber as well as the mode field diameter. The proposed fiber could be directly applied for dual-band dispersion and polarization control in fiber laser cavities as well as optical communications and sensors in the dual bands.</P>

Variation in Seed and Cone Characteristics of Loblolly Pine (Pinus taeda L.) Families in Southern Part of Korea

Lee, Hyunseok,Lim, Hyemin,Lee, Wiyoung,Jang, Kyunghwan,Kang, Junwon Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.1

Loblolly pine (Pinus taeda L.) is widely distributed in the southern part of the United States and it has been used as a major economic species in the region due to its excellent growth and stem straightness. The tree also grows only in the southern part of Korea because it is susceptible to cold. Recently climate changes have had widespread impacts on forest trees. Thus, the use of good quality seeds is prerequisite for assessing assisted migration adaptation trial. In this study, we conducted to investigate its cone and seed characteristics of each family, which is expected to improve seeds productivity for planting valuable timber trees. A total of 14 families were selected from the experimental forest in Boseong, Jeonnam province in 1981. The seed production capacity was estimated to range from 87.2 to 129.4 among families and the average was 111.3. The number of aborted ovules was investigated in the range of 11.4 to 29.5 for the first test and 7.4 to 22.2 for the second test. The average number of empty and filled seeds was 1.4 and 79.2 per cone, respectively. Based on the results, we can conclude that there is a strong correlation between the number of fertile scale and the seed production ability.

Component Analysis of Acorns of Quercus mongolica and Quercus Variabilis

Lee, Hyunseok,An, Chanhoon,Han, Sangurk,Lee, Wiyoung,Jang, Kyunghwan Institute of Forest Science 2016 Journal of Forest Science Vol.32 No.2

To compare seed components of plus trees, seed powder ground after seedcoat removal was analyzed for two oak species, i. e., Quercus monglica (white oak) and Quercus variabilis (red oak), which are typical oak trees in Korea but have different fruiting characteristics. Thus we aimed at analyzing and comparing many ingredients including minerals, sugars, etc. Two species were similar to each other in the content of water, crude ash, crude protein and carbohydrates, but crude lipid content in Q. variabilis was 2.5 times higher than that in Q. mongolica. Crude proteins of Clone 124 was 1.5 times higher than that of Clone 75 in Q. mongolica. Crude lipid content showed the highest value in Clone 0511 of Q. variabilis, and more phosphate and iron was found in Q. monglica than in Q. variabilis. Glucose showed 85.4% and 88.3% on average of the total monosacchrides in two species, and galactose and arabinose were also found. In the content of phosphate, iron, and crude lipid, differences were found between two species and among clones of two species.

Genome-wide transcriptomic analysis of BR-deficient Micro-Tom reveals correlations between drought stress tolerance and brassinosteroid signaling in tomato

Lee, Jinsu,Shim, Donghwan,Moon, Suyun,Kim, Hyemin,Bae, Wonsil,Kim, Kyunghwan,Kim, Yang-Hoon,Rhee, Sung-Keun,Hong, Chang Pyo,Hong, Suk-Young,Lee, Ye-Jin,Sung, Jwakyung,Ryu, Hojin Elsevier 2018 Plant physiology and biochemistry Vol.127 No.-

<P><B>Abstract</B></P> <P>Brassinosteroids (BRs) are plant steroid hormones that play crucial roles in a range of growth and developmental processes. Although BR signal transduction and biosynthetic pathways have been well characterized in model plants, their biological roles in an important crop, tomato (<I>Solanum lycopersicum</I>), remain unknown. Here, cultivated tomato (WT) and a BR synthesis mutant, Micro-Tom (MT), were compared using physiological and transcriptomic approaches. The cultivated tomato showed higher tolerance to drought and osmotic stresses than the MT tomato. However, BR-defective phenotypes of MT, including plant growth and stomatal closure defects, were completely recovered by application of exogenous BR or complementation with a <I>SlDWARF</I> gene. Using genome-wide transcriptome analysis, 619 significantly differentially expressed genes (DEGs) were identified between WT and MT plants. Several DEGs were linked to known signaling networks, including those related to biotic/abiotic stress responses, lignification, cell wall development, and hormone responses. Consistent with the higher susceptibility of MT to drought stress, several gene sets involved in responses to drought and osmotic stress were differentially regulated between the WT and MT tomato plants. Our data suggest that BR signaling pathways are involved in mediating the response to abiotic stress via fine-tuning of abiotic stress-related gene networks in tomato plants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> BR-deficient Micro-Tom showed lower drought and osmotic stress tolerance. </LI> <LI> Complementation of BR activity completely restored stress and developmental defects in Micro-Tom. </LI> <LI> BR signaling is tightly connected with gene networks related to abiotic stress and development. </LI> </UL> </P>

Separation of Corner Component in TAT Mechanism in Retention Characteristics of Sub 20-nm NAND Flash Memory

Kyunghwan Lee,Myounggon Kang,Seongjun Seo,Duckseoung Kang,Dong Hua Li,Yuchul Hwang,Hyungcheol Shin IEEE 2014 IEEE electron device letters Vol.35 No.1

<P>In this letter, we separated the corner and plane component of trap-assisted tunneling (TAT) mechanism and analyzed the retention characteristics in the world's smallest NAND flash memory (1X-nm generation). We found that the Ea of the corner component in TAT mechanism is smaller than that of the plane component due to the higher crowding electric field and larger trap density. The extracted Ea of both the components at the highest programmed Vth level (i.e., PV3 state) is smaller than that at PV2 state since the larger number of the stored electrons in floating gate increases the electric field across the tunneling oxide layer. It reduces the energy barrier between the traps and Ea. The ratio of the corner part over the plane one is larger at highly cycled and in smaller devices. For better understanding of the abnormal retention characteristics, each failure mechanism should be accurately analyzed.</P>

The study of Sports Injuries treatment with Korean Medicine : A survey of World Martial Arts Masterships' athletes and officials

Lee, Jaesung,Park, Jonghan,Park, Jangmi,Lee, Chamkyul,Jeong, Suhyeon,Kong, Kyunghwan,Lee, Eunyong The Society of Korean Medicine 2019 대한한의학회지 Vol.40 No.4

Objectives: The objective of this study was to report the general characteristics, satisfaction, and changes before and after treatment to foreign athletes and officials who were received Korean Medicine at the 2019 Chungju World Martial Arts Masterships Korean Medical Clinic. Methods: We investigated age, gender, nationality, type of sports, and, onset through medical records. Besides, we developed the patient satisfaction survey to determine how satisfied the patients were with the treatment they received. The survey included type of injury, location of the injury, cause of injury, Numeric Rating Scale (NRS) before and after treatment, and treatment satisfaction. Result: This study showed that knee and lower leg injuries (S80-S89) were the most frequent injuries in the Korean Medicine(KM) clinic of the 2019 Chungju World Martial Arts Masterships. We provided KM treatments including acupuncture, cupping therapy, Chuna manual therapy, herbal medicine, dressing, and taping. Acupuncture was the most frequently performed and the most satisfactory treatment. The average NRS after treatment significantly decreased, suggesting that KM is effective in controlling pain in sports injuries. The overall satisfaction was also high with KM treatments.

감염병 관련 법적 분쟁과 규제에 관한 합리적 해결방안

Lee, Kyunghwan,Kim, Taehwan,Kim, Mannoh,Han, Sunwoo 한국재난정보학회 2016 한국재난정보학회 논문집 Vol.12 No.2

최근의 MERS 사태를 통하여 감염병의 창궐은 사회의 재난이라는 인식과 함께 감염병의 확산과 관련한 법적인 문제가 사회적인 이슈로 떠올랐다. 감염병환자의 발생에 따르는 손해배상문제, 격리 대상자 및 의료기관의 전부 또는 일부 폐쇄 등으로 인한 보상문제, 감염병과 관련한 정보공개와 관한 문제가 대두되었다. 감염병과 관련한 부분은 지금까지 사회적으로 크게 문제가 된 적이 많지 않았기 때문에 관련된 법적인 이슈에 대한 연구가 다른 분야에 비해 상대적으로 적게 이루어진 것으로 보인다. MERS 사태로 인하여 해당 분야에 대한 사회적 관심이 고조된 만큼 감염병과 관련한 법적인 이슈에 대한 연구가 활발히 이루어져, 사회적 재난으로 확대될 수 있는 감염병(신종 홍콩독감, 에볼라, 지카 바이러스 등)을 조기에 예방하고 이에 대비할 수 있도록 만전을 기하여야 할 것이다. In the aftermath of a recent outbreak of Middle East respiratory syndrome (MERS), legal matters on the spread of epidemics have emerged as major social issues in Korea, with the awareness that rampant contagious diseases are disasters in society. Problems arose over damages arising from patients who contract infectious diseases, compensation for people under quarantine and for a partial, or entire, shutdown of hospitals, and information disclosure on infectious diseases. As epidemic-linked problems have never been socially disputed in Korea, the relevant legal issues appear to be studied comparatively less than other areas. As interests are heightened over legal issues on infectious illnesses amid the MERS scare, in-depth, further research on such legal issues should be conducted in an utmost effort to prevent and make preparations for epidemics which potentially become a social disaster, such as new Hong Kong flu, Ebola virus and Zika virus.

Brassinosteroids facilitate xylem differentiation and wood formation in tomato

Lee, Jinsu,Han, Seahee,Lee, Hwa-Yong,Jeong, Bomi,Heo, Tae-Young,Hyun, Tae Kyung,Kim, Kyunghwan,Je, Byoung Il,Lee, Horim,Shim, Donghwan,Park, Soon Ju,Ryu, Hojin Springer-Verlag 2019 Planta Vol.249 No.5

Accurate Lifetime Estimation of Sub-20-nm NAND Flash Memory

Kyunghwan Lee,Myounggon Kang,Yuchul Hwang,Hyungcheol Shin IEEE 2016 IEEE transactions on electron devices Vol.63 No.2

<P>Previously, we developed a charge loss/gain model for NAND flash memory, which is taking into account various failure mechanisms. In addition, we extracted all the parameters of the new model in the highest (PV3) and lowest states (ERS). In this paper, however, the physical information for the parameters and the whole procedure of the parameter extraction are covered in detail. We also extracted the contribution rate (CR) of dominant mechanisms at the criterion of vertical bar Delta V-th_Total vertical bar according to the baking temperature. The results give the physical reason for abnormal retention behaviors such as apparent activation energy (E-aa) roll-off at the PV3 state and negative E-aa at the ERS state. Using the proposed method, we extracted the accurate lifetime at room temperature in all states (PV3, PV2, PV1, and ERS). A large gap was observed in the results of the lifetime estimation, which were extracted by the conventional Arrhenius model and the proposed model. Since the proposed model takes into account the retention characteristics for various mechanisms, this model provides a much more accurate prediction for the lifetime.</P>

전산해석을 통한 지하 공동 및 암반 조건에 따른 철도지반 안정성 평가: 마장광산 갱도를 대상으로

장경환 ( Kyunghwan Jang ),이동원 ( Dongwon Lee ),민경남 ( Kyungnam Min ),정찬묵 ( Chanmook Chung ),유재형 ( Jaehyung Yu ),이계승 ( Gyeseung Lee ) 대한지질공학회 2021 지질공학 Vol.31 No.3

본 연구는 광산활동에 따른 철도지반 안정성 평가를 위해 채굴적의 심도, 규모 및 암반상태를 다양하게 설정하고, 표준열차하중 조건 중 여객, 화물 혼용 구간과 여객전용선 용도에 따른 지반안정성 평가를 전산해석을 통해 실시하였다. 안정성 평가는 철도설계기준 노반편에 따른 허용잔류 침하량과 선로유지관리지침 뒤틀림 보수조건을 기준으로 실시되었다. 그 결과, 채굴적의 규모 및 위치가 심도 5 m 이하일 경우 침하의 발생이 암반상태에 따라 노반 침하허용 기준을 넘어서며, 뒤틀림 보수기준에는 심도 15 m 이하의 공동일 경우 암반상태를 고려하여 지반보강 설계가 이루어져야 할 것으로 보인다. 노반의 침하허용 범위만 고려할 경우 심도 5 m 이하의 공동에서 암반상태가 고려되어야 한다. 이는 공동의 규모와 암반조건에 따른 침하량이 체계적으로 변화 함을 지시하며, 이러한 연구결과는 기존에 제시된 바가 없는 자료이다. 본 연구는 추후 철도건설이 광산지역에서 이루어질 경우 중요한 참고 자료로 활용될 수 있을 것으로 기대한다. This study used numerical modeling to investigate the stability of railway roadbed in areas with various underground cavities and rock conditions associated with mining activities. It compared combined loads from both passenger and freight trains with loads from only passenger trains. Stability was assessed with reference to the Korean government standards for railway subsidence allowance and railway warping repair. Sufficient stability regarding the railway subsidence allowance standard was not achieved when cavities were at depths of <5 m. The criteria for requiring railway warping repair were met when cavities were at depths of <15 m, depending on the rock fracture condition. This study provides the first report on systematic analysis land subsidence related to cavity size and rock fracture conditions associated with mining activities. We expect that this study could serve as an important reference for railway construction in mining areas.