Sangyeop Lee

Sangyeop Lee


Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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23 May 2024 in Sensors
Verified
Journal Article
Open access
PDF file
SLSangyeop Lee
Sangyeop Lee
JMJunhyung Moon
Junhyung Moon
YLYong Seung Lee
Yong Seung Lee
SSSeung-Chul Shin
Seung-Chul Shin
KLKyoungwoo Lee
Kyoungwoo Lee
Nocturnal enuresis (NE) is involuntary bedwetting during sleep, typically appearing in young children. Despite the potential benefits of the long-term home monitoring of NE patients for research and treatment enhancement, this area remains underexplored. To address this, we propose NEcare, an in-home monitoring system that utilizes wearable devices and machine learning techniques. NEcare collects sensor data from an electrocardiogram, body impedance (BI), a three-axis accelerometer, and a three-axis gyroscope to examine bladder volume (BV), heart rate (HR), and periodic limb movements in sleep (PLMS). Additionally, it analyzes the collected NE patient data and supports NE moment estimation using heuristic rules and deep learning techniques. To demonstrate the feasibility of in-home monitoring for NE patients using our wearable system, we used our datasets from 30 in-hospital patients and 4 in-home patients. The results show that NEcare captures expected trends associated with NE occurrences, including BV increase, HR increase, and PLMS appearance. In addition, we studied the machine learning-based NE moment estimation, which could help relieve the burdens of NE patients and their families. Finally, we address the limitations and outline future research directions for the development of wearable systems for NE patients

16 November 2020 in Neurourology and Urodynamics
Verified
Journal Article
Closed access
PDF file
SLSangyeop Lee
Sangyeop Lee
JMJunhyung Moon
Junhyung Moon
SSSeung‐Chul Shin
Seung‐Chul Shin
JHJi Hye Hwang
Ji Hye Hwang
KLKyoungwoo Lee
Kyoungwoo Lee
YLYong Seung Lee
Yong Seung Lee

5 December 2025 in Electronics
Verified
Journal Article
Open access
PDF file
SLSangyeop Lee
Sangyeop Lee
JKJong Seo Kim
Jong Seo Kim
KKKisoo Kim
Kisoo Kim
BKBojung Ko
Bojung Ko
JMJunho Moon
Junho Moon
MPMinsik Park
Minsik Park
Recent advances in large language models (LLMs) have enabled the effective representation of customer behaviors, including purchases, repairs, and consultations. These LLM-based customer representation models apply to predicting future behavior of the customer or clustering customers with similar representations by latent vectors. Since these representation technologies depend on data, this paper examines whether training a recommendation model (BERT4Rec) from scratch or fine-tuning a pre-trained LLM (ELECTRA) is more effective for our customer data. To address this, a three-step approach is conducted: (1) defining a sequence of customer behaviors into textual inputs for LLM-based representation learning, (2) extracting customer representation as latent vectors by training or fine-tuning representation models on a dataset of 14 million customers, and (3) training classifiers to predict purchase outcomes for eight products. Our focus is on comparing two primary approaches in step (2): training BERT4Rec from scratch versus fine-tuning pre-trained ELECTRA. The average AUC and F1-score of classifiers across eight products reveal that both methods achieve gaps of only 0.012 in AUC and 0.007 in F1-score. On the other hand, the fine-tuned ELECTRA achieves a 0.27 improvement in the top 10% lift for targeted marketing strategies. This result is particularly meaningful given that buyers of products constitute only about 0.5% of the entire dataset. Beyond the three-step approach, we make an effort to interpret latent space in two-dimensional and attention shifts in fine-tuned ELECTRA. Furthermore, we compare its efficiency advantages against fine-tuned LLaMA2. These findings provide practical insights for optimizing LLM-based representation models in industrial applications.