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Variation of Floating Potential in the Topside Ionosphere Observed by STSAT-1
Junhyun Lee,Ensang Lee,Jaejin Lee,Khan-Hyuk Kim,Jongho Seon,Dong-Hun Lee,Ho Jin,Eung-Hyun Kim,Hyun-Jin Jeon,Seong-Bin Lim,Taeyoun Kim,Jaewoong Jang,Kyung-Duk Jang,Kwangsun Ryu 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.4
In this study, we investigated the effect of space plasmas on the floating potential variation of a low-altitude, polar-orbiting satellite using the Langmuir Probe (LP) measurement onboard the STSAT-1 spacecraft. We focused on small potential drops, for which the estimation of plasma density and temperature from LP is available. The floating potential varied according to the variations of plasma density and temperature, similar to the previously reported observations. Most of the potential drops occurred around the nightside auroral region. However, unlike the previous studies where large potential drops were observed with the precipitation of auroral electrons, the potential drops occurred before or after the precipitation of auroral electrons. Statistical analysis shows that the potential drops have good correlation with the temperature increase of cold electrons, which suggests the small potential drops be mainly controlled by the cold ionospheric plasmas.
Song Hee Lee(Song Hee Lee),Young Taek Oh(Young Taek Oh),Do-Yeon Lee(Do-Yeon Lee),Eunbyeol Cho(Eunbyeol Cho),Byung Su Hwang(Byung Su Hwang),Junhyun Jeon(Junhyun Jeon) 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.6
Plants produce chemicals of immense diversity that provide great opportunities for development of new antifungal compounds. In search for environmentfriendly alternatives to the fungicide of current use, we screened plant extracts obtained from more than eight hundred plant materials collected in Korea for their antifungal activity against the model plant pathogenic fungus, Magnaporthe oryzae. This initial screening identified antifungal activities from the eleven plant extract samples, among which nine showed reproducibility in the follow-up screening. These nine samples were able to suppress not only M. oryzae but also other fungal pathogens. Interestingly, the plant extracts obtained from Actinostemma lobatum comprised five out of eight samples, and were the most effective in their antifungal activity. We found that butanol fraction of the A. lobatum extract is the most potent. Identification and characterization of antifungal substances in the A. lobatum extracts would provide the promising lead compounds for new fungicide.
Variation of Floating Potential in the Topside Ionosphere Observed by STSAT-1
Lee, Junhyun,Lee, Ensang,Lee, Jaejin,Kim, Khan-Hyuk,Seon, Jongho,Lee, Dong-Hun,Jin, Ho,Kim, Eung-Hyun,Jeon, Hyun-Jin,Lim, Seong-Bin,Kim, Taeyoun,Jang, Jaewoong,Jang, Kyung-Duk,Ryu, Kwangsun The Korean Space Science Society 2014 Journal of Astronomy and Space Sciences Vol.31 No.4
In this study, we investigated the effect of space plasmas on the floating potential variation of a low-altitude, polar-orbiting satellite using the Langmuir Probe (LP) measurement onboard the STSAT-1 spacecraft. We focused on small potential drops, for which the estimation of plasma density and temperature from LP is available. The floating potential varied according to the variations of plasma density and temperature, similar to the previously reported observations. Most of the potential drops occurred around the nightside auroral region. However, unlike the previous studies where large potential drops were observed with the precipitation of auroral electrons, the potential drops occurred before or after the precipitation of auroral electrons. Statistical analysis shows that the potential drops have good correlation with the temperature increase of cold electrons, which suggests the small potential drops be mainly controlled by the cold ionospheric plasmas.
Safety of Laparoscopic Radical Gastrectomy in Gastric Cancer Patients with End-Stage Renal Disease
Lee, Hayemin,Park, Cho Hyun,Park, Seung Man,Kim, Wook,Chin, Hyung Min,Kim, Jin Jo,Song, Kyo Young,Kim, Sung Geun,Jun, Kyong Hwa,Kim, Jeong Goo,Lee, Han Hong,Lee, Junhyun,Kim, Dong Jin The Korean Gastric Cancer Association 2018 Journal of gastric cancer Vol.18 No.3
Purpose: The surgical outcomes of end-stage renal disease (ESRD) patients undergoing radical gastrectomy for gastric cancer were inferior compared with those of non-ESRD patients. This study aimed to evaluate the short- and long-term surgical outcomes of ESRD patients undergoing laparoscopic gastrectomy (LG) and open gastrectomy (OG) for gastric cancer. Materials and Methods: Between 2004 and 2014, 38 patients (OG: 21 patients, LG: 17 patients) with ESRD underwent gastrectomy for gastric cancer. Comparisons were made based on the clinicopathological characteristics, surgical outcomes, and long-term survival rates. Results: No significant differences were noted in the clinicopathological characteristics of either group. LG patients had lower estimated blood loss volumes than OG patients (LG vs. OG: 94 vs. 275 mL, P=0.005). The operation time and postoperative hospital stay were similar in both the groups. The postoperative morbidity for LG and OG patients was 41.1% and 33.3%, respectively (P=0.873). No significant difference was observed in the long-term overall survival rates between the 2 groups (5-year overall survival, LG vs. OG: 82.4% vs. 64.7%, P=0.947). Conclusions: In ESRD patients, LG yielded non-inferior short- and long-term surgical outcomes compared to OG. Laparoscopic procedures might be safely adopted for ESRD patients who can benefit from the advantages of minimally invasive surgery.
Junhyun Lee,Dongjin Kim,Wook Kim 대한외과학회 2012 Annals of Surgical Treatment and Research(ASRT) Vol.82 No.3
Purpose: In laparoscopic distal gastrectomy for gastric cancer, most surgeons prefer extra-corporeal anastomosis because of technical challenges and unfamiliarity with intra-corporeal anastomosis. Herein, we report the feasibility and safety of intra-corporeal Billroth-Ⅱ anastomosis in gastric cancer. Methods: From April 2004 to March 2011, 130 underwent totally laparoscopic distal gastrectomy with intra-corporeal Billroth-Ⅱ reconstruction, and 269 patients underwent laparoscopy-assisted distal gastrectomy with extra-corporeal Billroth-Ⅱ reconstruction. Surgical efficacies and outcomes between two groups were compared. Results: There were no differences in demographics and clinicopathological characteristics. The mean operation and reconstruction times of totally laparoscopic distal gastrectomy were statistically shorter than laparoscopy-assisted distal gastrectomy (P = 0.019; P < 0.001). Anastomosis-related complications were observed in 11 (8.5%) totally laparoscopic distal gastrectomy and 21 (7.8%) laparoscopy-assisted distal gastrectomy patients, and the incidence of these events was not significantly different. Post-operative hospital stays for totally laparoscopic distal gastrectomy were shorter than laparoscopy-assisted distal gastrectomy patients (8.3 ± 3.2 days vs. 9.9 ± 5.3 days, respectively; P = 0.016), and the number of times parenteral analgesic administration was required in laparoscopy-assisted distal gastrectomy patients was more frequent after surgery. Conclusion: Intra-corporeal Billroth-Ⅱ anastomosis is a feasible procedure and can be safely performed with the proper experience for laparoscopic distal gastrectomy. This method may be less time consuming and may produce a more cosmetic result.
Worse Survival of Patients With T1 Stage II Gastric Cancer Following Radical Gastrectomy
Junhyun Lee,이하예민,Kyo Young Song,이한홍 대한위암학회 2023 Journal of gastric cancer Vol.23 No.4
Purpose: Lymph node (LN) metastasis is a crucial factor in the prognosis of patients with gastric cancer (GC) and is known to occur more frequently in cases with an advanced T stage. This study aimed to analyze the survival data of patients with advanced LN metastasis in T1 GC. Materials and Methods: From January 2008 to June 2018, 677 patients with pathological stage II GC who underwent radical gastrectomy were divided into an early GC group (EG: T1N2 and T1N3a, n=103) and an advanced GC (AGC) group (AG: T2N1, T2N2, T3N0, T3N1, and T4aN0, n=574). Short- and long-term survival rates were compared between the 2 groups. Results: A total of 80.6% (n=83) of the patients in the EG group and 52.8% (n=303) in the AG group had stage IIA AGC. The extent of LN dissection, number of retrieved LNs, and short-term morbidity and mortality rates did not differ between the 2 groups. The 5-year relapse-free survival (RFS) of all patients was 87.8% and the overall survival was 84.0%. RFS was lower in the EG group than in the AG group (82.2% vs. 88.7%, P=0.047). This difference was more pronounced among patients with stage IIA (82.4% vs. 92.9%, P=0.003). Conclusions: T1 GC with multiple LN metastases seems to have a worse prognosis compared to tumors with higher T-stages at the same level. Adjuvant chemotherapy is highly recommended for these patients, and future staging systems may require upstaging T1N2-stage tumors.
Lee, Seungyeob,Lee, Hayemin,Lee, Junhyun The Korean Gastric Cancer Association 2018 Journal of gastric cancer Vol.18 No.2
Purpose: Totally laparoscopic gastrectomy (TLG) for advanced gastric cancer (AGC) is a technically and oncologically challenging procedure for surgeons. This study aimed to compare the oncologic feasibility and technical safety of TLG for AGC versus early gastric cancer (EGC). Materials and Methods: Between 2011 and 2016, 535 patients (EGC, 375; AGC, 160) underwent curative TLG for gastric cancer. Clinicopathologic characteristics and surgical outcomes of both patient groups were analyzed and compared. Results: Patients with AGC required a longer operation time and experienced more intraoperative blood loss than those with EGC did. However, patients from both the AGC and EGC groups demonstrated similar short-term surgical outcomes such as postoperative morbidity (14.4% vs. 13.3%, P=0.626), mortality (0% vs. 0.5%, P=0.879), time-to-first oral intake (2.7 days for both groups, P=0.830), and postoperative hospital stay (10.2 days vs. 10.1 days, P=0.886). D2 lymph node dissection could be achieved in the AGC group (95%), with an adequate number of lymph nodes being dissected ($36.0{\pm}14.9$). In the AGC group, the 3-year overall and disease-free survival rates were 80.5% and 73.7%, respectively. Conclusions: TLG is as safe and effective for AGC as it is for EGC.
LEE, JUNHYUN,HA, SHINJUNG,JUNG, CHAN-KWON,LEE, HAN HONG Spandidos Publications 2015 International journal of oncology Vol.46 No.6
<P>Tumor metastases are the ultimate target in cancer therapy. In epithelial malignancies, the expression of high-mobility-group A2 (HMGA2) is associated with disease progression and the epithelial-mesenchymal transition (EMT), which is involved in the metastatic process. The present study assessed the clinical and molecular effects of HMGA2 with the malignant tissues of 170 patients with gastric cancer and gastric cancer cells expressing HMGA2. HMGA2 expression was determined using immunohistochemistry and analyzed with respect to the clinicopathological data of patients with this tumor. In the gastric cancer cell line MKN28, in which HMGA2 was knocked down by two different short-hairpin RNAs, Transwell migration and invasion assays were conducted and western blotting was used to detect the altered expression of EMT markers. In patients with gastric cancer, HMGA2 overexpression correlated with tumor progression and was indicative of a significantly worse overall survival. Migration and invasion assays using HMGA2-knocked down MKN28 cells showed a reduction in cell migration and invasion. The upregulation of E-cadherin, an epithelial marker, and the downregulation of N-cadherin, a mesenchymal marker were observed in HMGA2-knocked down cells. In addition, expression of the transcriptional factors Snail and Zeb1 and of the EMT-pathway molecule β-catenin were decreased. HMGA2 overexpression, through its relationship to EMT, thus seems to aggravate invasion and metastasis in gastric cancer. It may therefore serve as a predictive marker in determining the clinical outcome of patients with gastric cancer and offer a promising therapeutic target.</P>