1.A Qualitative Study of Psychological State of Suicide Victims through Suicide Notes.
Keunsoo HAM ; Chuyeon PYO ; Jongpil PARK ; Jooyoung NA ; Seong Ho YOO ; Ena LEE
Korean Journal of Legal Medicine 2014;38(4):155-166
Suicide notes are essential for investigating the psychological state of suicide victims and establishing suicide prevention programs. Since only a few studies have attempted to identify the causes of suicidal behavior through suicide notes, it would be worth examining suicide notes. Quantitative research on suicide has offered a limited understanding of suicide. Results showed that the suicide victims had used the suicide note as a tool for their last communication. Further, in addition to neutral contents such as directions for funeral, the note often contained information about precipitating events that caused the suicidal ideation. Writing a suicide note seemed to help the victims consider concrete plans for suicide. This study proved that qualitative research on suicide notes would be helpful for researchers to understand suicide victims in depth, which cannot be achieved by quantitative methods alone. Based on these results, several suggestions for suicide prevention programs were discussed.
Qualitative Research
;
Suicidal Ideation
;
Suicide*
;
Writing
2.Effects of Eye Movements on Recognition in a Manipulated-Face Memory Task.
Keunsoo HAM ; Chuyeon PYO ; Seong Ho YOO ; Jihye KWON
Korean Journal of Legal Medicine 2015;39(4):120-126
We evaluated the effects of eye movements on facial feature recognition and memory retrieval. Thirty-eight participants learned the faces of five men, including features of the faces (eyes, nose, and mouth), and then performed a recognition memory task for partially manipulated versions of the faces. Bilateral eye movements, recognition accuracy, and mean fixation duration were evaluated. We observed differences in fixation durations for the manipulated features of the faces (eyes, F(3,78)=11.95, P<0.001; and mouth, F(3,78)=21.38, P<0.001). These findings demonstrate that eye movements have a functional role in learning and recognizing human faces. Furthermore, fixation durations increased for the manipulated facial features, suggesting that eye movements during recognition are not simply patterns produced during learning.
Eye Movements*
;
Humans
;
Learning
;
Male
;
Memory*
;
Mouth
;
Nose
3.Estimation of Eyewitness Identification Accuracy by Event-Related Potentials.
Keunsoo HAM ; Chuyeon PYO ; Taeik JANG ; Seong Ho YOO
Korean Journal of Legal Medicine 2015;39(4):115-119
We investigated event-related potentials (ERPs) to estimate the accuracy of eyewitness memories. Participants watched videos of vehicles being driven dangerously, from an anti-impaired driving initiative. The four-letter license plates of the vehicles were the target stimuli. Random numbers were presented while participants attempted to identify the license plate letters, and electroencephalograms were recorded. There was a significant difference in activity 300-500 milliseconds after stimulus onset, between target stimuli and random numbers. This finding contributes to establishing an eyewitness recognition model where different ERP components may reflect more explicit memory that is dissociable from recollection.
Electroencephalography
;
Event-Related Potentials, P300
;
Evoked Potentials*
;
Licensure
;
Memory
4.The Assessment of Eyewitness Memory Using Electroencephalogram: Application of Machine Learning Algorithm
Keunsoo HAM ; Ki Pyeong KIM ; Hojin JEONG ; Seong Ho YOO
Korean Journal of Legal Medicine 2018;42(2):62-70
This study was conducted to investigate whether memory accuracy can be assessed by analyzing electrophysiological responses (i.e., electroencephalography [EEG]) for retrieval cues related to the witnessed scene. Specifically, we examined the different patterns of EEG signals recorded during witnessed (target) and unwitnessed (lure) stimuli using event-related potential (ERP) analysis. Moreover, using multivariate pattern analysis, we also assessed how accurately single-trial EEG signals can classify target and lure stimuli. Participants watched a staged-crime video (theft crime), and the EEG signals evoked by the objects shown in the video were analyzed (n=56). Compared to the target stimulus, the lure stimulus elicited larger negative ERPs in frontal brain regions 300 to 500 milliseconds after the retrieval cue was presented. Furthermore, the EEG signals observed 450 to 500 milliseconds after the retrieval cue was presented showed the best classification performance related to eyewitness memory, with the mean classification accuracy being 56%. These results suggest that the knowledge and techniques of cognitive neuroscience can be used to estimate eyewitness memory accuracy.
Brain
;
Classification
;
Cognitive Neuroscience
;
Cues
;
Electroencephalography
;
Evoked Potentials
;
Machine Learning
;
Memory
5.Increased Ventrolateral Prefrontal Cortex Activation during Accurate Eyewitness Memory Retrieval: An Exploratory Functional Near-Infrared Spectroscopy Study
Keunsoo HAM ; Ki Pyoung KIM ; Hojin JEONG ; Seong Ho YOO
Korean Journal of Legal Medicine 2018;42(4):146-152
We investigated the neural correlates of accurate eyewitness memory retrieval using functional near-infrared spectroscopy. We analyzed oxygenated hemoglobin (HbO₂) concentration in the prefrontal cortex during eyewitness memory retrieval task and examined regional HbO₂ differences between observed objects (target) and unobserved objects (lure). We found that target objects elicited increased activation in the bilateral ventrolateral prefrontal cortex, which is known for monitoring retrieval processing via bottom-up attentional processing. Our results suggest bottom-up attentional mechanisms could be different during accurate eyewitness memory retrieval. These findings indicate that investigating retrieval mechanisms using functional nearinfrared spectroscopy might be useful for establishing an accurate eyewitness recognition model.
Cognitive Neuroscience
;
Memory
;
Oxygen
;
Prefrontal Cortex
;
Spectroscopy, Near-Infrared
;
Spectrum Analysis
6.The Assessment of Eyewitness Memory Using Electroencephalogram: Application of Machine Learning Algorithm
Keunsoo HAM ; Ki Pyeong KIM ; Hojin JEONG ; Seong Ho YOO
Korean Journal of Legal Medicine 2018;42(2):62-70
This study was conducted to investigate whether memory accuracy can be assessed by analyzing electrophysiological responses (i.e., electroencephalography [EEG]) for retrieval cues related to the witnessed scene. Specifically, we examined the different patterns of EEG signals recorded during witnessed (target) and unwitnessed (lure) stimuli using event-related potential (ERP) analysis. Moreover, using multivariate pattern analysis, we also assessed how accurately single-trial EEG signals can classify target and lure stimuli. Participants watched a staged-crime video (theft crime), and the EEG signals evoked by the objects shown in the video were analyzed (n=56). Compared to the target stimulus, the lure stimulus elicited larger negative ERPs in frontal brain regions 300 to 500 milliseconds after the retrieval cue was presented. Furthermore, the EEG signals observed 450 to 500 milliseconds after the retrieval cue was presented showed the best classification performance related to eyewitness memory, with the mean classification accuracy being 56%. These results suggest that the knowledge and techniques of cognitive neuroscience can be used to estimate eyewitness memory accuracy.
7.Increased Ventrolateral Prefrontal Cortex Activation during Accurate Eyewitness Memory Retrieval: An Exploratory Functional Near-Infrared Spectroscopy Study
Keunsoo HAM ; Ki Pyoung KIM ; Hojin JEONG ; Seong Ho YOO
Korean Journal of Legal Medicine 2018;42(4):146-152
We investigated the neural correlates of accurate eyewitness memory retrieval using functional near-infrared spectroscopy. We analyzed oxygenated hemoglobin (HbOâ‚‚) concentration in the prefrontal cortex during eyewitness memory retrieval task and examined regional HbOâ‚‚ differences between observed objects (target) and unobserved objects (lure). We found that target objects elicited increased activation in the bilateral ventrolateral prefrontal cortex, which is known for monitoring retrieval processing via bottom-up attentional processing. Our results suggest bottom-up attentional mechanisms could be different during accurate eyewitness memory retrieval. These findings indicate that investigating retrieval mechanisms using functional nearinfrared spectroscopy might be useful for establishing an accurate eyewitness recognition model.
8.Open heart surgery:clinical analysis of 100cases.
Sang Ho RHIE ; Seong Kyu CHUNG ; Sung Ho KIM ; Jun Young CHOI ; Young Kyun CHUNG ; Yoon CHOI ; Heon Geun LEE ; Shee Young HAM
The Korean Journal of Thoracic and Cardiovascular Surgery 1993;26(5):360-364
No abstract available.
Heart*
9.CELL-DYN Sapphire Hematology Analyzer Performance Evaluation on Leukocyte Differential Counts.
Seong Ho KANG ; Euiseuk SHIN ; Chun Kyung HAM ; Hyun Kyung KIM ; Han Ik CHO
Journal of Laboratory Medicine and Quality Assurance 2006;28(2):219-224
BACKGROUND: Recent advances of hematology analyzers have improved performance of leukocyte differential counts and have reduced work load of clinical hematology laboratories. We evaluated CELL-DYN Sapphire (Abbott Diagnostics, Santa Clara, CA, USA) performance on leukocyte differential counts according to Clinical and Laboratory Standards Institute (CLSI) document H20-A. METHODS: We evaluated imprecision (short term imprecision from duplication of 147 patients' sample and long term imprecision from three level commercial controls) and accuracy (n=462) of leukocyte differential counts of CELL-DYN Sapphire and compared with those of Sysmex XE-2100 (TOA Medical Electronics Co., Kobe, Japan), ADVIA 120 (Bayer Diagnostics, Tarrytown, NY, USA) and Beckman Coulter LH 750 (Beckman Coulter, Miami, FL, USA). RESULTS: The imprecision of CELL-DYN Sapphire for neutrophils and lymphocytes differentials was low with coefficients of variation (CV) from 1.4 to 6.2%, but the imprecision for basophils was high with CV from 34.7 to 79.6%. The correlation with manual count was good in samples without flags (n=314), with the exception of basophils (r: neutrophils, 0.921; lymphocytes, 0.921; monocytes, 0.653; eosinophils, 0.869; basophils 0.272). The correlation with other hematology analyzers was high except basophils (r: neutrophils, 0.969-0.986; lymphocytes, 0.986-0.990; monocytes, 0.787-0.887; eosinophils, 0.881-0.962; basophils 0.086-0.327). CONCLUSION: The performance on leukocyte differential counts of CELL-DYN Sapphire is comparable to Sysmex XE-2100, ADVIA 120 and Beckman Coulter LH 750. In regards of enumeration of basophils, the comparison with manual counts and other hematology analyzers shows poor agreement.
Aluminum Oxide*
;
Basophils
;
Electronics, Medical
;
Eosinophils
;
Hematology*
;
Leukocytes*
;
Lymphocytes
;
Monocytes
;
Neutrophils
10.Endoscopic Ligation of Large Gastric Varices Using a Detachable Snares and Rubber Bands.
Chan Sup SHIM ; Joon Seong LEE ; Jong Tae LEE ; Moon Sung LEE ; Joo Young CHO ; Young Deok CHO ; Cheol Ho PARK ; Jeong Sik HAM ; Hyung Keun BONG ; Jin Oh KIM ; Yun Soo KIM ; Seong Gyu HWANG
Korean Journal of Gastrointestinal Endoscopy 1995;15(4):670-677
Bleeding from gastric varices greater than 2cm in diameter represents a major limitation for endoscopic hemostasis. The endoscopic injection sclerotherapy (EIS) using conventional sclerosing agents is not satisfactory for the control of acute bleeding from gastric varices which have large diameter, fast blood flow and abundant collateral circulations. Endoscopic ligation using small rubber bands, known to be alternative to EIS, never obliterate large gastric varices greater than 2 cm in diameter. Obliteration therapy using Histoacryl (n-buty1-2-cyanoacrylate), known to be more satisfactory, has some drawback such as embolization. We per formed endoscopic ligation using detachable snares and rubber bands in 22 patients who had recently bleeding from gastric varices larger than 2 cm in diameter. For ligation of gastric varices larger than 2 cm in diameter, the detachable snares were used, and then for ligation of adjacent small gastric varices, rubber bands were used. In seven patients active bleedings were noted at initial endoscopy; 6 of them were successfully controlled by endoscopic ligation using detachable snares and rubber bands, but one patient who was uncontrolled by it died from bleeding and multiple organ failure. In remaining 15 patients, there were no active bleeding but red color signs on large gastric varices; all of them were successfully controlled by endoscopic ligation using detachable snares and rubber bands. Early rebleeding, fol lowing initial treatment, occurred in two patients (9.5%). So overall hemostatic rate of endoscopic ligation using the detachable snares and the rubber bands was 86.4% (19/22). Varices were nearly eradicated in 18 (85.7%) of the 21 survivors by ligation of 1-3 detachable snares (mean, l.3 snares) and 4-30 rubber bands (mean, 16,2 bands) in 2-6 sessions (mean, 3.2 sessions). During or after ligation, there were no serious complications, except transient epigastric pain or discomfort in 14.7% and fever in 1.3%. These results suggest that endoscopic ligation therapy with detachable snares and rubber bands is a safe and effective method for treatment of acute bleeding of gastric varices, especially gastric varices larger than 2 cm in diameter, which can not he controlled by conventional scleratherapy or variceal band ligation.
Collateral Circulation
;
Enbucrilate
;
Endoscopy
;
Esophageal and Gastric Varices*
;
Fever
;
Hemorrhage
;
Hemostasis, Endoscopic
;
Humans
;
Ligation*
;
Multiple Organ Failure
;
Rubber*
;
Sclerosing Solutions
;
Sclerotherapy
;
SNARE Proteins*
;
Survivors
;
Varicose Veins